Ubuntu Manpage: tor - The second-generation onion router

NAME

       tor - The second-generation onion router

SYNOPSIS

       tor [OPTION value]...

DESCRIPTION

       Tor is a connection-oriented anonymizing communication service. Users choose a
       source-routed path through a set of nodes, and negotiate a "virtual circuit" through the
       network, in which each node knows its predecessor and successor, but no others. Traffic
       flowing down the circuit is unwrapped by a symmetric key at each node, which reveals the
       downstream node.

       Basically, Tor provides a distributed network of servers or relays ("onion routers").
       Users bounce their TCP streams — web traffic, ftp, ssh, etc. — around the network, and
       recipients, observers, and even the relays themselves have difficulty tracking the source
       of the stream.

       By default, tor will act as a client only. To help the network by providing bandwidth as a
       relay, change the ORPort configuration option — see below. Please also consult the
       documentation on the Tor Project’s website.

COMMAND-LINE OPTIONS

-h, -help
Display a short help message and exit.

-f FILE
Specify a new configuration file to contain further Tor configuration options OR pass
- to make Tor read its configuration from standard input. (Default: /etc/tor/torrc, or
$HOME/.torrc if that file is not found)

--allow-missing-torrc
Do not require that configuration file specified by -f exist if default torrc can be
accessed.

--defaults-torrc FILE
Specify a file in which to find default values for Tor options. The contents of this
file are overridden by those in the regular configuration file, and by those on the
command line. (Default: /etc/tor/torrc-defaults.)

--ignore-missing-torrc
Specifies that Tor should treat a missing torrc file as though it were empty.
Ordinarily, Tor does this for missing default torrc files, but not for those specified
on the command line.

--hash-password PASSWORD
Generates a hashed password for control port access.

--list-fingerprint
Generate your keys and output your nickname and fingerprint.

--verify-config
Verify the configuration file is valid.

--service install [--options command-line options]
Install an instance of Tor as a Windows service, with the provided command-line
options. Current instructions can be found at
https://www.torproject.org/docs/faq#NTService

--service remove|start|stop
Remove, start, or stop a configured Tor Windows service.

--nt-service
Used internally to implement a Windows service.

--list-torrc-options
List all valid options.

--list-deprecated-options
List all valid options that are scheduled to become obsolete in a future version.
(This is a warning, not a promise.)

--version
Display Tor version and exit.

--quiet|--hush
Override the default console log. By default, Tor starts out logging messages at level
"notice" and higher to the console. It stops doing so after it parses its
configuration, if the configuration tells it to log anywhere else. You can override
this behavior with the --hush option, which tells Tor to only send warnings and errors
to the console, or with the --quiet option, which tells Tor not to log to the console
at all.

--keygen [--newpass]
Running "tor --keygen" creates a new ed25519 master identity key for a relay, or only
a fresh temporary signing key and certificate, if you already have a master key.
Optionally you can encrypt the master identity key with a passphrase: Tor will ask you
for one. If you don’t want to encrypt the master key, just don’t enter any passphrase
when asked.

The --newpass option should be used with --keygen only when you need to add, change,
or remove a passphrase on an existing ed25519 master identity key. You will be
prompted for the old passphase (if any), and the new passphrase (if any).

When generating a master key, you will probably want to use --DataDirectory to control
where the keys and certificates will be stored, and --SigningKeyLifetime to control
their lifetimes. Their behavior is as documented in the server options section below.
(You must have write access to the specified DataDirectory.)

To use the generated files, you must copy them to the DataDirectory/keys directory of
your Tor daemon, and make sure that they are owned by the user actually running the
Tor daemon on your system.

--passphrase-fd FILEDES
Filedescriptor to read the passphrase from. Note that unlike with the tor-gencert
program, the entire file contents are read and used as the passphrase, including any
trailing newlines. Default: read from the terminal.

--key-expiration [purpose]
The purpose specifies which type of key certificate to determine the expiration of.
The only currently recognised purpose is "sign".

Running "tor --key-expiration sign" will attempt to find your signing key certificate
and will output, both in the logs as well as to stdout, the signing key certificate’s
expiration time in ISO-8601 format. For example, the output sent to stdout will be of
the form: "signing-cert-expiry: 2017-07-25 08:30:15 UTC"

Other options can be specified on the command-line in the format "--option value", in the
format "option value", or in a configuration file. For instance, you can tell Tor to start
listening for SOCKS connections on port 9999 by passing --SocksPort 9999 or SocksPort 9999
to it on the command line, or by putting "SocksPort 9999" in the configuration file. You
will need to quote options with spaces in them: if you want Tor to log all debugging
messages to debug.log, you will probably need to say --Log debug file debug.log.

Options on the command line override those in configuration files. See the next section
for more information.

THE CONFIGURATION FILE FORMAT

All configuration options in a configuration are written on a single line by default. They
take the form of an option name and a value, or an option name and a quoted value (option
value or option "value"). Anything after a # character is treated as a comment. Options
are case-insensitive. C-style escaped characters are allowed inside quoted values. To
split one configuration entry into multiple lines, use a single backslash character (\)
before the end of the line. Comments can be used in such multiline entries, but they must
start at the beginning of a line.

Configuration options can be imported from files or folders using the %include option with
the value being a path. If the path is a file, the options from the file will be parsed as
if they were written where the %include option is. If the path is a folder, all files on
that folder will be parsed following lexical order. Files starting with a dot are ignored.
Files on subfolders are ignored. The %include option can be used recursively.

By default, an option on the command line overrides an option found in the configuration
file, and an option in a configuration file overrides one in the defaults file.

This rule is simple for options that take a single value, but it can become complicated
for options that are allowed to occur more than once: if you specify four SocksPorts in
your configuration file, and one more SocksPort on the command line, the option on the
command line will replace all of the SocksPorts in the configuration file. If this isn’t
what you want, prefix the option name with a plus sign (+), and it will be appended to the
previous set of options instead. For example, setting SocksPort 9100 will use only port
9100, but setting +SocksPort 9100 will use ports 9100 and 9050 (because this is the
default).

Alternatively, you might want to remove every instance of an option in the configuration
file, and not replace it at all: you might want to say on the command line that you want
no SocksPorts at all. To do that, prefix the option name with a forward slash (/). You can
use the plus sign (+) and the forward slash (/) in the configuration file and on the
command line.

GENERAL OPTIONS

BandwidthRate N bytes|KBytes|MBytes|GBytes|TBytes|KBits|MBits|GBits|TBits
A token bucket limits the average incoming bandwidth usage on this node to the
specified number of bytes per second, and the average outgoing bandwidth usage to that
same value. If you want to run a relay in the public network, this needs to be at the
very least 75 KBytes for a relay (that is, 600 kbits) or 50 KBytes for a bridge (400
kbits) — but of course, more is better; we recommend at least 250 KBytes (2 mbits) if
possible. (Default: 1 GByte)

Note that this option, and other bandwidth-limiting options, apply to TCP data only:
They do not count TCP headers or DNS traffic.

With this option, and in other options that take arguments in bytes, KBytes, and so
on, other formats are also supported. Notably, "KBytes" can also be written as
"kilobytes" or "kb"; "MBytes" can be written as "megabytes" or "MB"; "kbits" can be
written as "kilobits"; and so forth. Tor also accepts "byte" and "bit" in the
singular. The prefixes "tera" and "T" are also recognized. If no units are given, we
default to bytes. To avoid confusion, we recommend writing "bytes" or "bits"
explicitly, since it’s easy to forget that "B" means bytes, not bits.

MaxAdvertisedBandwidth N bytes|KBytes|MBytes|GBytes|TBytes|KBits|MBits|GBits|TBits
If set, we will not advertise more than this amount of bandwidth for our
BandwidthRate. Server operators who want to reduce the number of clients who ask to
build circuits through them (since this is proportional to advertised bandwidth rate)
can thus reduce the CPU demands on their server without impacting network performance.

RelayBandwidthRate N bytes|KBytes|MBytes|GBytes|TBytes|KBits|MBits|GBits|TBits
If not 0, a separate token bucket limits the average incoming bandwidth usage for
_relayed traffic_ on this node to the specified number of bytes per second, and the
average outgoing bandwidth usage to that same value. Relayed traffic currently is
calculated to include answers to directory requests, but that may change in future
versions. (Default: 0)

ClientTransportPlugin transport socks4|socks5 IP:PORT, ClientTransportPlugin transport
exec path-to-binary [options]
In its first form, when set along with a corresponding Bridge line, the Tor client
forwards its traffic to a SOCKS-speaking proxy on "IP:PORT". (IPv4 addresses should
written as-is; IPv6 addresses should be wrapped in square brackets.) It’s the duty of
that proxy to properly forward the traffic to the bridge.

In its second form, when set along with a corresponding Bridge line, the Tor client
launches the pluggable transport proxy executable in path-to-binary using options as
its command-line options, and forwards its traffic to it. It’s the duty of that proxy
to properly forward the traffic to the bridge.

ServerTransportPlugin transport exec path-to-binary [options]
The Tor relay launches the pluggable transport proxy in path-to-binary using options
as its command-line options, and expects to receive proxied client traffic from it.

ServerTransportListenAddr transport IP:PORT
When this option is set, Tor will suggest IP:PORT as the listening address of any
pluggable transport proxy that tries to launch transport. (IPv4 addresses should
written as-is; IPv6 addresses should be wrapped in square brackets.)

ServerTransportOptions transport k=v k=v ...
When this option is set, Tor will pass the k=v parameters to any pluggable transport
proxy that tries to launch transport.

(Example: ServerTransportOptions obfs45 shared-secret=bridgepasswd
cache=/var/lib/tor/cache)

ExtORPort [address:]port|auto
Open this port to listen for Extended ORPort connections from your pluggable
transports.

ExtORPortCookieAuthFile Path
If set, this option overrides the default location and file name for the Extended
ORPort’s cookie file — the cookie file is needed for pluggable transports to
communicate through the Extended ORPort.

ExtORPortCookieAuthFileGroupReadable 0|1
If this option is set to 0, don’t allow the filesystem group to read the Extended OR
Port cookie file. If the option is set to 1, make the cookie file readable by the
default GID. [Making the file readable by other groups is not yet implemented; let us
know if you need this for some reason.] (Default: 0)

ConnLimit NUM
The minimum number of file descriptors that must be available to the Tor process
before it will start. Tor will ask the OS for as many file descriptors as the OS will
allow (you can find this by "ulimit -H -n"). If this number is less than ConnLimit,
then Tor will refuse to start.

You probably don’t need to adjust this. It has no effect on Windows since that
platform lacks getrlimit(). (Default: 1000)

DisableNetwork 0|1
When this option is set, we don’t listen for or accept any connections other than
controller connections, and we close (and don’t reattempt) any outbound connections.
Controllers sometimes use this option to avoid using the network until Tor is fully
configured. (Default: 0)

ConstrainedSockets 0|1
If set, Tor will tell the kernel to attempt to shrink the buffers for all sockets to
the size specified in ConstrainedSockSize. This is useful for virtual servers and
other environments where system level TCP buffers may be limited. If you’re on a
virtual server, and you encounter the "Error creating network socket: No buffer space
available" message, you are likely experiencing this problem.

The preferred solution is to have the admin increase the buffer pool for the host
itself via /proc/sys/net/ipv4/tcp_mem or equivalent facility; this configuration
option is a second-resort.

The DirPort option should also not be used if TCP buffers are scarce. The cached
directory requests consume additional sockets which exacerbates the problem.

You should not enable this feature unless you encounter the "no buffer space
available" issue. Reducing the TCP buffers affects window size for the TCP stream and
will reduce throughput in proportion to round trip time on long paths. (Default: 0)

ConstrainedSockSize N bytes|KBytes
When ConstrainedSockets is enabled the receive and transmit buffers for all sockets
will be set to this limit. Must be a value between 2048 and 262144, in 1024 byte
increments. Default of 8192 is recommended.

ControlPort PORT|unix:path|auto [flags]
If set, Tor will accept connections on this port and allow those connections to
control the Tor process using the Tor Control Protocol (described in control-spec.txt
in torspec). Note: unless you also specify one or more of HashedControlPassword or
CookieAuthentication, setting this option will cause Tor to allow any process on the
local host to control it. (Setting both authentication methods means either method is
sufficient to authenticate to Tor.) This option is required for many Tor controllers;
most use the value of 9051. If a unix domain socket is used, you may quote the path
using standard C escape sequences. Set it to "auto" to have Tor pick a port for you.
(Default: 0)

Recognized flags are...

GroupWritable
Unix domain sockets only: makes the socket get created as group-writable.

WorldWritable
Unix domain sockets only: makes the socket get created as world-writable.

RelaxDirModeCheck
Unix domain sockets only: Do not insist that the directory that holds the socket
be read-restricted.

ControlSocket Path
Like ControlPort, but listens on a Unix domain socket, rather than a TCP socket. 0
disables ControlSocket (Unix and Unix-like systems only.)

ControlSocketsGroupWritable 0|1
If this option is set to 0, don’t allow the filesystem group to read and write unix
sockets (e.g. ControlSocket). If the option is set to 1, make the control socket
readable and writable by the default GID. (Default: 0)

HashedControlPassword hashed_password
Allow connections on the control port if they present the password whose one-way hash
is hashed_password. You can compute the hash of a password by running "tor
--hash-password password". You can provide several acceptable passwords by using more
than one HashedControlPassword line.

CookieAuthentication 0|1
If this option is set to 1, allow connections on the control port when the connecting
process knows the contents of a file named "control_auth_cookie", which Tor will
create in its data directory. This authentication method should only be used on
systems with good filesystem security. (Default: 0)

CookieAuthFile Path
If set, this option overrides the default location and file name for Tor’s cookie
file. (See CookieAuthentication above.)

CookieAuthFileGroupReadable 0|1
If this option is set to 0, don’t allow the filesystem group to read the cookie file.
If the option is set to 1, make the cookie file readable by the default GID. [Making
the file readable by other groups is not yet implemented; let us know if you need this
for some reason.] (Default: 0)

ControlPortWriteToFile Path
If set, Tor writes the address and port of any control port it opens to this address.
Usable by controllers to learn the actual control port when ControlPort is set to
"auto".

ControlPortFileGroupReadable 0|1
If this option is set to 0, don’t allow the filesystem group to read the control port
file. If the option is set to 1, make the control port file readable by the default
GID. (Default: 0)

DataDirectory DIR
Store working data in DIR. Can not be changed while tor is running. (Default: ~/.tor
if your home directory is not /; otherwise, /var/lib/tor. On Windows, the default is
your ApplicationData folder.)

DataDirectoryGroupReadable 0|1
If this option is set to 0, don’t allow the filesystem group to read the
DataDirectory. If the option is set to 1, make the DataDirectory readable by the
default GID. (Default: 0)

FallbackDir ipv4address:port orport=port id=fingerprint [weight=num]
[ipv6=[ipv6address]:orport]
When we’re unable to connect to any directory cache for directory info (usually
because we don’t know about any yet) we try a directory authority. Clients also
simultaneously try a FallbackDir, to avoid hangs on client startup if a directory
authority is down. Clients retry FallbackDirs more often than directory authorities,
to reduce the load on the directory authorities. By default, the directory authorities
are also FallbackDirs. Specifying a FallbackDir replaces Tor’s default hard-coded
FallbackDirs (if any). (See the DirAuthority entry for an explanation of each flag.)

UseDefaultFallbackDirs 0|1
Use Tor’s default hard-coded FallbackDirs (if any). (When a FallbackDir line is
present, it replaces the hard-coded FallbackDirs, regardless of the value of
UseDefaultFallbackDirs.) (Default: 1)

DirAuthority [nickname] [flags] ipv4address:port fingerprint
Use a nonstandard authoritative directory server at the provided address and port,
with the specified key fingerprint. This option can be repeated many times, for
multiple authoritative directory servers. Flags are separated by spaces, and determine
what kind of an authority this directory is. By default, an authority is not
authoritative for any directory style or version unless an appropriate flag is given.
Tor will use this authority as a bridge authoritative directory if the "bridge" flag
is set. If a flag "orport=port" is given, Tor will use the given port when opening
encrypted tunnels to the dirserver. If a flag "weight=num" is given, then the
directory server is chosen randomly with probability proportional to that weight
(default 1.0). If a flag "v3ident=fp" is given, the dirserver is a v3 directory
authority whose v3 long-term signing key has the fingerprint fp. Lastly, if an
"ipv6=[ipv6address]:orport" flag is present, then the directory authority is listening
for IPv6 connections on the indicated IPv6 address and OR Port.

Tor will contact the authority at ipv4address to download directory documents. The
provided port value is a dirport; clients ignore this in favor of the specified
"orport=" value. If an IPv6 ORPort is supplied, Tor will also download directory
documents at the IPv6 ORPort.

If no DirAuthority line is given, Tor will use the default directory authorities.
NOTE: this option is intended for setting up a private Tor network with its own
directory authorities. If you use it, you will be distinguishable from other users,
because you won’t believe the same authorities they do.

DirAuthorityFallbackRate NUM
When configured to use both directory authorities and fallback directories, the
directory authorities also work as fallbacks. They are chosen with their regular
weights, multiplied by this number, which should be 1.0 or less. The default is less
than 1, to reduce load on authorities. (Default: 0.1)

AlternateDirAuthority [nickname] [flags] ipv4address:port fingerprint

AlternateBridgeAuthority [nickname] [flags] ipv4address:port fingerprint
These options behave as DirAuthority, but they replace fewer of the default directory
authorities. Using AlternateDirAuthority replaces the default Tor directory
authorities, but leaves the default bridge authorities in place. Similarly,
AlternateBridgeAuthority replaces the default bridge authority, but leaves the
directory authorities alone.

DisableAllSwap 0|1
If set to 1, Tor will attempt to lock all current and future memory pages, so that
memory cannot be paged out. Windows, OS X and Solaris are currently not supported. We
believe that this feature works on modern Gnu/Linux distributions, and that it should
work on *BSD systems (untested). This option requires that you start your Tor as root,
and you should use the User option to properly reduce Tor’s privileges. Can not be
changed while tor is running. (Default: 0)

DisableDebuggerAttachment 0|1
If set to 1, Tor will attempt to prevent basic debugging attachment attempts by other
processes. This may also keep Tor from generating core files if it crashes. It has no
impact for users who wish to attach if they have CAP_SYS_PTRACE or if they are root.
We believe that this feature works on modern Gnu/Linux distributions, and that it may
also work on *BSD systems (untested). Some modern Gnu/Linux systems such as Ubuntu
have the kernel.yama.ptrace_scope sysctl and by default enable it as an attempt to
limit the PTRACE scope for all user processes by default. This feature will attempt to
limit the PTRACE scope for Tor specifically - it will not attempt to alter the system
wide ptrace scope as it may not even exist. If you wish to attach to Tor with a
debugger such as gdb or strace you will want to set this to 0 for the duration of your
debugging. Normal users should leave it on. Disabling this option while Tor is running
is prohibited. (Default: 1)

FetchDirInfoEarly 0|1
If set to 1, Tor will always fetch directory information like other directory caches,
even if you don’t meet the normal criteria for fetching early. Normal users should
leave it off. (Default: 0)

FetchDirInfoExtraEarly 0|1
If set to 1, Tor will fetch directory information before other directory caches. It
will attempt to download directory information closer to the start of the consensus
period. Normal users should leave it off. (Default: 0)

FetchHidServDescriptors 0|1
If set to 0, Tor will never fetch any hidden service descriptors from the rendezvous
directories. This option is only useful if you’re using a Tor controller that handles
hidden service fetches for you. (Default: 1)

FetchServerDescriptors 0|1
If set to 0, Tor will never fetch any network status summaries or server descriptors
from the directory servers. This option is only useful if you’re using a Tor
controller that handles directory fetches for you. (Default: 1)

FetchUselessDescriptors 0|1
If set to 1, Tor will fetch every consensus flavor, descriptor, and certificate that
it hears about. Otherwise, it will avoid fetching useless descriptors: flavors that it
is not using to build circuits, and authority certificates it does not trust. This
option is useful if you’re using a tor client with an external parser that uses a full
consensus. This option fetches all documents, DirCache fetches and serves all
documents. (Default: 0)

HTTPProxy host[:port]
Tor will make all its directory requests through this host:port (or host:80 if port is
not specified), rather than connecting directly to any directory servers. (DEPRECATED:
As of 0.3.1.0-alpha you should use HTTPSProxy.)

HTTPProxyAuthenticator username:password
If defined, Tor will use this username:password for Basic HTTP proxy authentication,
as in RFC 2617. This is currently the only form of HTTP proxy authentication that Tor
supports; feel free to submit a patch if you want it to support others. (DEPRECATED:
As of 0.3.1.0-alpha you should use HTTPSProxyAuthenticator.)

HTTPSProxy host[:port]
Tor will make all its OR (SSL) connections through this host:port (or host:443 if port
is not specified), via HTTP CONNECT rather than connecting directly to servers. You
may want to set FascistFirewall to restrict the set of ports you might try to connect
to, if your HTTPS proxy only allows connecting to certain ports.

HTTPSProxyAuthenticator username:password
If defined, Tor will use this username:password for Basic HTTPS proxy authentication,
as in RFC 2617. This is currently the only form of HTTPS proxy authentication that Tor
supports; feel free to submit a patch if you want it to support others.

Sandbox 0|1
If set to 1, Tor will run securely through the use of a syscall sandbox. Otherwise the
sandbox will be disabled. The option is currently an experimental feature. It only
works on Linux-based operating systems, and only when Tor has been built with the
libseccomp library. This option can not be changed while tor is running.

When the Sandbox is 1, the following options can not be changed when tor is running:
Address ConnLimit CookieAuthFile DirPortFrontPage ExtORPortCookieAuthFile Logs
ServerDNSResolvConfFile Tor must remain in client or server mode (some changes to
ClientOnly and ORPort are not allowed). (Default: 0)

Socks4Proxy host[:port]
Tor will make all OR connections through the SOCKS 4 proxy at host:port (or host:1080
if port is not specified).

Socks5Proxy host[:port]
Tor will make all OR connections through the SOCKS 5 proxy at host:port (or host:1080
if port is not specified).

Socks5ProxyUsername username

Socks5ProxyPassword password
If defined, authenticate to the SOCKS 5 server using username and password in
accordance to RFC 1929. Both username and password must be between 1 and 255
characters.

SocksSocketsGroupWritable 0|1
If this option is set to 0, don’t allow the filesystem group to read and write unix
sockets (e.g. SocksSocket). If the option is set to 1, make the SocksSocket socket
readable and writable by the default GID. (Default: 0)

KeepalivePeriod NUM
To keep firewalls from expiring connections, send a padding keepalive cell every NUM
seconds on open connections that are in use. If the connection has no open circuits,
it will instead be closed after NUM seconds of idleness. (Default: 5 minutes)

Log minSeverity[-maxSeverity] stderr|stdout|syslog
Send all messages between minSeverity and maxSeverity to the standard output stream,
the standard error stream, or to the system log. (The "syslog" value is only supported
on Unix.) Recognized severity levels are debug, info, notice, warn, and err. We advise
using "notice" in most cases, since anything more verbose may provide sensitive
information to an attacker who obtains the logs. If only one severity level is given,
all messages of that level or higher will be sent to the listed destination.

Log minSeverity[-maxSeverity] file FILENAME
As above, but send log messages to the listed filename. The "Log" option may appear
more than once in a configuration file. Messages are sent to all the logs that match
their severity level.

Log [domain,...]minSeverity[-maxSeverity] ... file FILENAME

Log [domain,...]minSeverity[-maxSeverity] ... stderr|stdout|syslog
As above, but select messages by range of log severity and by a set of "logging
domains". Each logging domain corresponds to an area of functionality inside Tor. You
can specify any number of severity ranges for a single log statement, each of them
prefixed by a comma-separated list of logging domains. You can prefix a domain with ~
to indicate negation, and use * to indicate "all domains". If you specify a severity
range without a list of domains, it matches all domains.

This is an advanced feature which is most useful for debugging one or two of Tor’s
subsystems at a time.

The currently recognized domains are: general, crypto, net, config, fs, protocol, mm,
http, app, control, circ, rend, bug, dir, dirserv, or, edge, acct, hist, and
handshake. Domain names are case-insensitive.

For example, "Log [handshake]debug [~net,~mm]info notice stdout" sends to stdout: all
handshake messages of any severity, all info-and-higher messages from domains other
than networking and memory management, and all messages of severity notice or higher.

LogMessageDomains 0|1
If 1, Tor includes message domains with each log message. Every log message currently
has at least one domain; most currently have exactly one. This doesn’t affect
controller log messages. (Default: 0)

MaxUnparseableDescSizeToLog N bytes|KBytes|MBytes|GBytes|TBytes
Unparseable descriptors (e.g. for votes, consensuses, routers) are logged in separate
files by hash, up to the specified size in total. Note that only files logged during
the lifetime of this Tor process count toward the total; this is intended to be used
to debug problems without opening live servers to resource exhaustion attacks.
(Default: 10 MB)

OutboundBindAddress IP
Make all outbound connections originate from the IP address specified. This is only
useful when you have multiple network interfaces, and you want all of Tor’s outgoing
connections to use a single one. This option may be used twice, once with an IPv4
address and once with an IPv6 address. IPv6 addresses should be wrapped in square
brackets. This setting will be ignored for connections to the loopback addresses
(127.0.0.0/8 and ::1).

OutboundBindAddressOR IP
Make all outbound non-exit (relay and other) connections originate from the IP address
specified. This option overrides OutboundBindAddress for the same IP version. This
option may be used twice, once with an IPv4 address and once with an IPv6 address.
IPv6 addresses should be wrapped in square brackets. This setting will be ignored for
connections to the loopback addresses (127.0.0.0/8 and ::1).

OutboundBindAddressExit IP
Make all outbound exit connections originate from the IP address specified. This
option overrides OutboundBindAddress for the same IP version. This option may be used
twice, once with an IPv4 address and once with an IPv6 address. IPv6 addresses should
be wrapped in square brackets. This setting will be ignored for connections to the
loopback addresses (127.0.0.0/8 and ::1).

PidFile FILE
On startup, write our PID to FILE. On clean shutdown, remove FILE. Can not be changed
while tor is running.

ProtocolWarnings 0|1
If 1, Tor will log with severity 'warn' various cases of other parties not following
the Tor specification. Otherwise, they are logged with severity 'info'. (Default: 0)

RunAsDaemon 0|1
If 1, Tor forks and daemonizes to the background. This option has no effect on
Windows; instead you should use the --service command-line option. Can not be changed
while tor is running. (Default: 0)

LogTimeGranularity NUM
Set the resolution of timestamps in Tor’s logs to NUM milliseconds. NUM must be
positive and either a divisor or a multiple of 1 second. Note that this option only
controls the granularity written by Tor to a file or console log. Tor does not (for
example) "batch up" log messages to affect times logged by a controller, times
attached to syslog messages, or the mtime fields on log files. (Default: 1 second)

TruncateLogFile 0|1
If 1, Tor will overwrite logs at startup and in response to a HUP signal, instead of
appending to them. (Default: 0)

SyslogIdentityTag tag
When logging to syslog, adds a tag to the syslog identity such that log entries are
marked with "Tor-tag". Can not be changed while tor is running. (Default: none)

SafeLogging 0|1|relay
Tor can scrub potentially sensitive strings from log messages (e.g. addresses) by
replacing them with the string [scrubbed]. This way logs can still be useful, but they
don’t leave behind personally identifying information about what sites a user might
have visited.

If this option is set to 0, Tor will not perform any scrubbing, if it is set to 1, all
potentially sensitive strings are replaced. If it is set to relay, all log messages
generated when acting as a relay are sanitized, but all messages generated when acting
as a client are not. (Default: 1)

User Username
On startup, setuid to this user and setgid to their primary group. Can not be changed
while tor is running.

KeepBindCapabilities 0|1|auto
On Linux, when we are started as root and we switch our identity using the User
option, the KeepBindCapabilities option tells us whether to try to retain our ability
to bind to low ports. If this value is 1, we try to keep the capability; if it is 0 we
do not; and if it is auto, we keep the capability only if we are configured to listen
on a low port. Can not be changed while tor is running. (Default: auto.)

HardwareAccel 0|1
If non-zero, try to use built-in (static) crypto hardware acceleration when available.
Can not be changed while tor is running. (Default: 0)

AccelName NAME
When using OpenSSL hardware crypto acceleration attempt to load the dynamic engine of
this name. This must be used for any dynamic hardware engine. Names can be verified
with the openssl engine command. Can not be changed while tor is running.

AccelDir DIR
Specify this option if using dynamic hardware acceleration and the engine
implementation library resides somewhere other than the OpenSSL default. Can not be
changed while tor is running.

AvoidDiskWrites 0|1
If non-zero, try to write to disk less frequently than we would otherwise. This is
useful when running on flash memory or other media that support only a limited number
of writes. (Default: 0)

CircuitPriorityHalflife NUM1
If this value is set, we override the default algorithm for choosing which circuit’s
cell to deliver or relay next. When the value is 0, we round-robin between the active
circuits on a connection, delivering one cell from each in turn. When the value is
positive, we prefer delivering cells from whichever connection has the lowest weighted
cell count, where cells are weighted exponentially according to the supplied
CircuitPriorityHalflife value (in seconds). If this option is not set at all, we use
the behavior recommended in the current consensus networkstatus. This is an advanced
option; you generally shouldn’t have to mess with it. (Default: not set)

CountPrivateBandwidth 0|1
If this option is set, then Tor’s rate-limiting applies not only to remote
connections, but also to connections to private addresses like 127.0.0.1 or 10.0.0.1.
This is mostly useful for debugging rate-limiting. (Default: 0)

ExtendByEd25519ID 0|1|auto
If this option is set to 1, we always try to include a relay’s Ed25519 ID when telling
the proceeding relay in a circuit to extend to it. If this option is set to 0, we
never include Ed25519 IDs when extending circuits. If the option is set to "default",
we obey a parameter in the consensus document. (Default: auto)

NoExec 0|1
If this option is set to 1, then Tor will never launch another executable, regardless
of the settings of PortForwardingHelper, ClientTransportPlugin, or
ServerTransportPlugin. Once this option has been set to 1, it cannot be set back to 0
without restarting Tor. (Default: 0)

Schedulers KIST|KISTLite|Vanilla
Specify the scheduler type that tor should use. The scheduler is responsible for
moving data around within a Tor process. This is an ordered list by priority which
means that the first value will be tried first and if unavailable, the second one is
tried and so on. It is possible to change these values at runtime. This option mostly
effects relays, and most operators should leave it set to its default value. (Default:
KIST,KISTLite,Vanilla)

The possible scheduler types are:

KIST: Kernel-Informed Socket Transport. Tor will use TCP information from the kernel
to make informed decisions regarding how much data to send and when to send it. KIST
also handles traffic in batches (see KISTSchedRunInterval) in order to improve traffic
prioritization decisions. As implemented, KIST will only work on Linux kernel version
2.6.39 or higher.

KISTLite: Same as KIST but without kernel support. Tor will use all the same mechanics
as with KIST, including the batching, but its decisions regarding how much data to
send will not be as good. KISTLite will work on all kernels and operating systems, and
the majority of the benefits of KIST are still realized with KISTLite.

Vanilla: The scheduler that Tor used before KIST was implemented. It sends as much
data as possible, as soon as possible. Vanilla will work on all kernels and operating
systems.

KISTSchedRunInterval NUM msec
If KIST or KISTLite is used in the Schedulers option, this controls at which interval
the scheduler tick is. If the value is 0 msec, the value is taken from the consensus
if possible else it will fallback to the default 10 msec. Maximum possible value is
100 msec. (Default: 0 msec)

KISTSockBufSizeFactor NUM
If KIST is used in Schedulers, this is a multiplier of the per-socket limit
calculation of the KIST algorithm. (Default: 1.0)

CLIENT OPTIONS

The following options are useful only for clients (that is, if SocksPort, HTTPTunnelPort,
TransPort, DNSPort, or NATDPort is non-zero):

Bridge [transport] IP:ORPort [fingerprint]
When set along with UseBridges, instructs Tor to use the relay at "IP:ORPort" as a
"bridge" relaying into the Tor network. If "fingerprint" is provided (using the same
format as for DirAuthority), we will verify that the relay running at that location
has the right fingerprint. We also use fingerprint to look up the bridge descriptor at
the bridge authority, if it’s provided and if UpdateBridgesFromAuthority is set too.

If "transport" is provided, it must match a ClientTransportPlugin line. We then use
that pluggable transport’s proxy to transfer data to the bridge, rather than
connecting to the bridge directly. Some transports use a transport-specific method to
work out the remote address to connect to. These transports typically ignore the
"IP:ORPort" specified in the bridge line.

Tor passes any "key=val" settings to the pluggable transport proxy as per-connection
arguments when connecting to the bridge. Consult the documentation of the pluggable
transport for details of what arguments it supports.

LearnCircuitBuildTimeout 0|1
If 0, CircuitBuildTimeout adaptive learning is disabled. (Default: 1)

CircuitBuildTimeout NUM
Try for at most NUM seconds when building circuits. If the circuit isn’t open in that
time, give up on it. If LearnCircuitBuildTimeout is 1, this value serves as the
initial value to use before a timeout is learned. If LearnCircuitBuildTimeout is 0,
this value is the only value used. (Default: 60 seconds)

CircuitsAvailableTimeout NUM
Tor will attempt to keep at least one open, unused circuit available for this amount
of time. This option governs how long idle circuits are kept open, as well as the
amount of time Tor will keep a circuit open to each of the recently used ports. This
way when the Tor client is entirely idle, it can expire all of its circuits, and then
expire its TLS connections. Note that the actual timeout value is uniformly randomized
from the specified value to twice that amount. (Default: 30 minutes; Max: 24 hours)

CircuitStreamTimeout NUM
If non-zero, this option overrides our internal timeout schedule for how many seconds
until we detach a stream from a circuit and try a new circuit. If your network is
particularly slow, you might want to set this to a number like 60. (Default: 0)

ClientOnly 0|1
If set to 1, Tor will not run as a relay or serve directory requests, even if the
ORPort, ExtORPort, or DirPort options are set. (This config option is mostly
unnecessary: we added it back when we were considering having Tor clients auto-promote
themselves to being relays if they were stable and fast enough. The current behavior
is simply that Tor is a client unless ORPort, ExtORPort, or DirPort are configured.)
(Default: 0)

ConnectionPadding 0|1|auto
This option governs Tor’s use of padding to defend against some forms of traffic
analysis. If it is set to auto, Tor will send padding only if both the client and the
relay support it. If it is set to 0, Tor will not send any padding cells. If it is set
to 1, Tor will still send padding for client connections regardless of relay support.
Only clients may set this option. This option should be offered via the UI to mobile
users for use where bandwidth may be expensive. (Default: auto)

ReducedConnectionPadding 0|1
If set to 1, Tor will not not hold OR connections open for very long, and will send
less padding on these connections. Only clients may set this option. This option
should be offered via the UI to mobile users for use where bandwidth may be expensive.
(Default: 0)

ExcludeNodes node,node,...
A list of identity fingerprints, country codes, and address patterns of nodes to avoid
when building a circuit. Country codes are 2-letter ISO3166 codes, and must be wrapped
in braces; fingerprints may be preceded by a dollar sign. (Example: ExcludeNodes
ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, {cc}, 255.254.0.0/8)

By default, this option is treated as a preference that Tor is allowed to override in
order to keep working. For example, if you try to connect to a hidden service, but you
have excluded all of the hidden service’s introduction points, Tor will connect to one
of them anyway. If you do not want this behavior, set the StrictNodes option
(documented below).

Note also that if you are a relay, this (and the other node selection options below)
only affects your own circuits that Tor builds for you. Clients can still build
circuits through you to any node. Controllers can tell Tor to build circuits through
any node.

Country codes are case-insensitive. The code "{??}" refers to nodes whose country
can’t be identified. No country code, including {??}, works if no GeoIPFile can be
loaded. See also the GeoIPExcludeUnknown option below.

ExcludeExitNodes node,node,...
A list of identity fingerprints, country codes, and address patterns of nodes to never
use when picking an exit node---that is, a node that delivers traffic for you outside
the Tor network. Note that any node listed in ExcludeNodes is automatically considered
to be part of this list too. See the ExcludeNodes option for more information on how
to specify nodes. See also the caveats on the "ExitNodes" option below.

GeoIPExcludeUnknown 0|1|auto
If this option is set to auto, then whenever any country code is set in ExcludeNodes
or ExcludeExitNodes, all nodes with unknown country ({??} and possibly {A1}) are
treated as excluded as well. If this option is set to 1, then all unknown countries
are treated as excluded in ExcludeNodes and ExcludeExitNodes. This option has no
effect when a GeoIP file isn’t configured or can’t be found. (Default: auto)

ExitNodes node,node,...
A list of identity fingerprints, country codes, and address patterns of nodes to use
as exit node---that is, a node that delivers traffic for you outside the Tor network.
See the ExcludeNodes option for more information on how to specify nodes.

Note that if you list too few nodes here, or if you exclude too many exit nodes with
ExcludeExitNodes, you can degrade functionality. For example, if none of the exits you
list allows traffic on port 80 or 443, you won’t be able to browse the web.

Note also that not every circuit is used to deliver traffic outside of the Tor
network. It is normal to see non-exit circuits (such as those used to connect to
hidden services, those that do directory fetches, those used for relay reachability
self-tests, and so on) that end at a non-exit node. To keep a node from being used
entirely, see ExcludeNodes and StrictNodes.

The ExcludeNodes option overrides this option: any node listed in both ExitNodes and
ExcludeNodes is treated as excluded.

The .exit address notation, if enabled via MapAddress, overrides this option.

EntryNodes node,node,...
A list of identity fingerprints and country codes of nodes to use for the first hop in
your normal circuits. Normal circuits include all circuits except for direct
connections to directory servers. The Bridge option overrides this option; if you have
configured bridges and UseBridges is 1, the Bridges are used as your entry nodes.

The ExcludeNodes option overrides this option: any node listed in both EntryNodes and
ExcludeNodes is treated as excluded. See the ExcludeNodes option for more information
on how to specify nodes.

StrictNodes 0|1
If StrictNodes is set to 1, Tor will treat solely the ExcludeNodes option as a
requirement to follow for all the circuits you generate, even if doing so will break
functionality for you (StrictNodes applies to neither ExcludeExitNodes nor to
ExitNodes). If StrictNodes is set to 0, Tor will still try to avoid nodes in the
ExcludeNodes list, but it will err on the side of avoiding unexpected errors.
Specifically, StrictNodes 0 tells Tor that it is okay to use an excluded node when it
is necessary to perform relay reachability self-tests, connect to a hidden service,
provide a hidden service to a client, fulfill a .exit request, upload directory
information, or download directory information. (Default: 0)

FascistFirewall 0|1
If 1, Tor will only create outgoing connections to ORs running on ports that your
firewall allows (defaults to 80 and 443; see FirewallPorts). This will allow you to
run Tor as a client behind a firewall with restrictive policies, but will not allow
you to run as a server behind such a firewall. If you prefer more fine-grained
control, use ReachableAddresses instead.

FirewallPorts PORTS
A list of ports that your firewall allows you to connect to. Only used when
FascistFirewall is set. This option is deprecated; use ReachableAddresses instead.
(Default: 80, 443)

ReachableAddresses IP[/MASK][:PORT]...
A comma-separated list of IP addresses and ports that your firewall allows you to
connect to. The format is as for the addresses in ExitPolicy, except that "accept" is
understood unless "reject" is explicitly provided. For example, 'ReachableAddresses
99.0.0.0/8, reject 18.0.0.0/8:80, accept *:80' means that your firewall allows
connections to everything inside net 99, rejects port 80 connections to net 18, and
accepts connections to port 80 otherwise. (Default: 'accept *:*'.)

ReachableDirAddresses IP[/MASK][:PORT]...
Like ReachableAddresses, a list of addresses and ports. Tor will obey these
restrictions when fetching directory information, using standard HTTP GET requests. If
not set explicitly then the value of ReachableAddresses is used. If HTTPProxy is set
then these connections will go through that proxy. (DEPRECATED: This option has had no
effect for some time.)

ReachableORAddresses IP[/MASK][:PORT]...
Like ReachableAddresses, a list of addresses and ports. Tor will obey these
restrictions when connecting to Onion Routers, using TLS/SSL. If not set explicitly
then the value of ReachableAddresses is used. If HTTPSProxy is set then these
connections will go through that proxy.

The separation between ReachableORAddresses and ReachableDirAddresses is only
interesting when you are connecting through proxies (see HTTPProxy and HTTPSProxy).
Most proxies limit TLS connections (which Tor uses to connect to Onion Routers) to
port 443, and some limit HTTP GET requests (which Tor uses for fetching directory
information) to port 80.

HidServAuth onion-address auth-cookie [service-name]
Client authorization for a hidden service. Valid onion addresses contain 16 characters
in a-z2-7 plus ".onion", and valid auth cookies contain 22 characters in A-Za-z0-9+/.
The service name is only used for internal purposes, e.g., for Tor controllers. This
option may be used multiple times for different hidden services. If a hidden service
uses authorization and this option is not set, the hidden service is not accessible.
Hidden services can be configured to require authorization using the
HiddenServiceAuthorizeClient option.

LongLivedPorts PORTS
A list of ports for services that tend to have long-running connections (e.g. chat and
interactive shells). Circuits for streams that use these ports will contain only
high-uptime nodes, to reduce the chance that a node will go down before the stream is
finished. Note that the list is also honored for circuits (both client and service
side) involving hidden services whose virtual port is in this list. (Default: 21, 22,
706, 1863, 5050, 5190, 5222, 5223, 6523, 6667, 6697, 8300)

MapAddress address newaddress
When a request for address arrives to Tor, it will transform to newaddress before
processing it. For example, if you always want connections to www.example.com to exit
via torserver (where torserver is the fingerprint of the server), use "MapAddress
www.example.com www.example.com.torserver.exit". If the value is prefixed with a "*.",
matches an entire domain. For example, if you always want connections to example.com
and any if its subdomains to exit via torserver (where torserver is the fingerprint of
the server), use "MapAddress *.example.com *.example.com.torserver.exit". (Note the
leading "*." in each part of the directive.) You can also redirect all subdomains of a
domain to a single address. For example, "MapAddress *.example.com www.example.com".

NOTES:

1. When evaluating MapAddress expressions Tor stops when it hits the most recently
added expression that matches the requested address. So if you have the following
in your torrc, www.torproject.org will map to 1.1.1.1:

MapAddress www.torproject.org 2.2.2.2
MapAddress www.torproject.org 1.1.1.1

2. Tor evaluates the MapAddress configuration until it finds no matches. So if you
have the following in your torrc, www.torproject.org will map to 2.2.2.2:

MapAddress 1.1.1.1 2.2.2.2
MapAddress www.torproject.org 1.1.1.1

3. The following MapAddress expression is invalid (and will be ignored) because you
cannot map from a specific address to a wildcard address:

MapAddress www.torproject.org *.torproject.org.torserver.exit

4. Using a wildcard to match only part of a string (as in *ample.com) is also
invalid.

NewCircuitPeriod NUM
Every NUM seconds consider whether to build a new circuit. (Default: 30 seconds)

MaxCircuitDirtiness NUM
Feel free to reuse a circuit that was first used at most NUM seconds ago, but never
attach a new stream to a circuit that is too old. For hidden services, this applies to
the last time a circuit was used, not the first. Circuits with streams constructed
with SOCKS authentication via SocksPorts that have KeepAliveIsolateSOCKSAuth also
remain alive for MaxCircuitDirtiness seconds after carrying the last such stream.
(Default: 10 minutes)

MaxClientCircuitsPending NUM
Do not allow more than NUM circuits to be pending at a time for handling client
streams. A circuit is pending if we have begun constructing it, but it has not yet
been completely constructed. (Default: 32)

NodeFamily node,node,...
The Tor servers, defined by their identity fingerprints, constitute a "family" of
similar or co-administered servers, so never use any two of them in the same circuit.
Defining a NodeFamily is only needed when a server doesn’t list the family itself
(with MyFamily). This option can be used multiple times; each instance defines a
separate family. In addition to nodes, you can also list IP address and ranges and
country codes in {curly braces}. See the ExcludeNodes option for more information on
how to specify nodes.

EnforceDistinctSubnets 0|1
If 1, Tor will not put two servers whose IP addresses are "too close" on the same
circuit. Currently, two addresses are "too close" if they lie in the same /16 range.
(Default: 1)

SocksPort [address:]port|unix:path|auto [flags] [isolation flags]
Open this port to listen for connections from SOCKS-speaking applications. Set this to
0 if you don’t want to allow application connections via SOCKS. Set it to "auto" to
have Tor pick a port for you. This directive can be specified multiple times to bind
to multiple addresses/ports. If a unix domain socket is used, you may quote the path
using standard C escape sequences. (Default: 9050)

NOTE: Although this option allows you to specify an IP address other than localhost,
you should do so only with extreme caution. The SOCKS protocol is unencrypted and (as
we use it) unauthenticated, so exposing it in this way could leak your information to
anybody watching your network, and allow anybody to use your computer as an open
proxy.

The isolation flags arguments give Tor rules for which streams received on this
SocksPort are allowed to share circuits with one another. Recognized isolation flags
are:

IsolateClientAddr
Don’t share circuits with streams from a different client address. (On by default
and strongly recommended when supported; you can disable it with
NoIsolateClientAddr. Unsupported and force-disabled when using Unix domain
sockets.)

IsolateSOCKSAuth
Don’t share circuits with streams for which different SOCKS authentication was
provided. (For HTTPTunnelPort connections, this option looks at the
Proxy-Authorization and X-Tor-Stream-Isolation headers. On by default; you can
disable it with NoIsolateSOCKSAuth.)

IsolateClientProtocol
Don’t share circuits with streams using a different protocol. (SOCKS 4, SOCKS 5,
TransPort connections, NATDPort connections, and DNSPort requests are all
considered to be different protocols.)

IsolateDestPort
Don’t share circuits with streams targeting a different destination port.

IsolateDestAddr
Don’t share circuits with streams targeting a different destination address.

KeepAliveIsolateSOCKSAuth
If IsolateSOCKSAuth is enabled, keep alive circuits while they have at least one
stream with SOCKS authentication active. After such a circuit is idle for more
than MaxCircuitDirtiness seconds, it can be closed.

SessionGroup=INT
If no other isolation rules would prevent it, allow streams on this port to share
circuits with streams from every other port with the same session group. (By
default, streams received on different SocksPorts, TransPorts, etc are always
isolated from one another. This option overrides that behavior.)

Other recognized flags for a SocksPort are:

NoIPv4Traffic
Tell exits to not connect to IPv4 addresses in response to SOCKS requests on this
connection.

IPv6Traffic
Tell exits to allow IPv6 addresses in response to SOCKS requests on this
connection, so long as SOCKS5 is in use. (SOCKS4 can’t handle IPv6.)

PreferIPv6
Tells exits that, if a host has both an IPv4 and an IPv6 address, we would prefer
to connect to it via IPv6. (IPv4 is the default.)

NoDNSRequest
Do not ask exits to resolve DNS addresses in SOCKS5 requests. Tor will connect to
IPv4 addresses, IPv6 addresses (if IPv6Traffic is set) and .onion addresses.

NoOnionTraffic
Do not connect to .onion addresses in SOCKS5 requests.

OnionTrafficOnly
Tell the tor client to only connect to .onion addresses in response to SOCKS5
requests on this connection. This is equivalent to NoDNSRequest, NoIPv4Traffic,
NoIPv6Traffic. The corresponding NoOnionTrafficOnly flag is not supported.

CacheIPv4DNS
Tells the client to remember IPv4 DNS answers we receive from exit nodes via this
connection. (On by default.)

CacheIPv6DNS
Tells the client to remember IPv6 DNS answers we receive from exit nodes via this
connection.

GroupWritable
Unix domain sockets only: makes the socket get created as group-writable.

WorldWritable
Unix domain sockets only: makes the socket get created as world-writable.

CacheDNS
Tells the client to remember all DNS answers we receive from exit nodes via this
connection.

UseIPv4Cache
Tells the client to use any cached IPv4 DNS answers we have when making requests
via this connection. (NOTE: This option, along UseIPv6Cache and UseDNSCache, can
harm your anonymity, and probably won’t help performance as much as you might
expect. Use with care!)

UseIPv6Cache
Tells the client to use any cached IPv6 DNS answers we have when making requests
via this connection.

UseDNSCache
Tells the client to use any cached DNS answers we have when making requests via
this connection.

PreferIPv6Automap
When serving a hostname lookup request on this port that should get automapped
(according to AutomapHostsOnResolve), if we could return either an IPv4 or an IPv6
answer, prefer an IPv6 answer. (On by default.)

PreferSOCKSNoAuth
Ordinarily, when an application offers both "username/password authentication" and
"no authentication" to Tor via SOCKS5, Tor selects username/password
authentication so that IsolateSOCKSAuth can work. This can confuse some
applications, if they offer a username/password combination then get confused when
asked for one. You can disable this behavior, so that Tor will select "No
authentication" when IsolateSOCKSAuth is disabled, or when this option is set.

Flags are processed left to right. If flags conflict, the last flag on the line is
used, and all earlier flags are ignored. No error is issued for conflicting flags.

SocksPolicy policy,policy,...
Set an entrance policy for this server, to limit who can connect to the SocksPort and
DNSPort ports. The policies have the same form as exit policies below, except that
port specifiers are ignored. Any address not matched by some entry in the policy is
accepted.

SocksTimeout NUM
Let a socks connection wait NUM seconds handshaking, and NUM seconds unattached
waiting for an appropriate circuit, before we fail it. (Default: 2 minutes)

TokenBucketRefillInterval NUM [msec|second]
Set the refill interval of Tor’s token bucket to NUM milliseconds. NUM must be between
1 and 1000, inclusive. Note that the configured bandwidth limits are still expressed
in bytes per second: this option only affects the frequency with which Tor checks to
see whether previously exhausted connections may read again. Can not be changed while
tor is running. (Default: 100 msec)

TrackHostExits host,.domain,...
For each value in the comma separated list, Tor will track recent connections to hosts
that match this value and attempt to reuse the same exit node for each. If the value
is prepended with a '.', it is treated as matching an entire domain. If one of the
values is just a '.', it means match everything. This option is useful if you
frequently connect to sites that will expire all your authentication cookies (i.e. log
you out) if your IP address changes. Note that this option does have the disadvantage
of making it more clear that a given history is associated with a single user.
However, most people who would wish to observe this will observe it through cookies or
other protocol-specific means anyhow.

TrackHostExitsExpire NUM
Since exit servers go up and down, it is desirable to expire the association between
host and exit server after NUM seconds. The default is 1800 seconds (30 minutes).

UpdateBridgesFromAuthority 0|1
When set (along with UseBridges), Tor will try to fetch bridge descriptors from the
configured bridge authorities when feasible. It will fall back to a direct request if
the authority responds with a 404. (Default: 0)

UseBridges 0|1
When set, Tor will fetch descriptors for each bridge listed in the "Bridge" config
lines, and use these relays as both entry guards and directory guards. (Default: 0)

UseEntryGuards 0|1
If this option is set to 1, we pick a few long-term entry servers, and try to stick
with them. This is desirable because constantly changing servers increases the odds
that an adversary who owns some servers will observe a fraction of your paths. Entry
Guards can not be used by Directory Authorities, Single Onion Services, and Tor2web
clients. In these cases, the this option is ignored. (Default: 1)

GuardfractionFile FILENAME
V3 authoritative directories only. Configures the location of the guardfraction file
which contains information about how long relays have been guards. (Default: unset)

UseGuardFraction 0|1|auto
This torrc option specifies whether clients should use the guardfraction information
found in the consensus during path selection. If it’s set to auto, clients will do
what the UseGuardFraction consensus parameter tells them to do. (Default: auto)

NumEntryGuards NUM
If UseEntryGuards is set to 1, we will try to pick a total of NUM routers as long-term
entries for our circuits. If NUM is 0, we try to learn the number from the
guard-n-primary-guards-to-use consensus parameter, and default to 1 if the consensus
parameter isn’t set. (Default: 0)

NumDirectoryGuards NUM
If UseEntryGuards is set to 1, we try to make sure we have at least NUM routers to use
as directory guards. If this option is set to 0, use the value from the
guard-n-primary-dir-guards-to-use consensus parameter, and default to 3 if the
consensus parameter isn’t set. (Default: 0)

GuardLifetime N days|weeks|months
If nonzero, and UseEntryGuards is set, minimum time to keep a guard before picking a
new one. If zero, we use the GuardLifetime parameter from the consensus directory. No
value here may be less than 1 month or greater than 5 years; out-of-range values are
clamped. (Default: 0)

SafeSocks 0|1
When this option is enabled, Tor will reject application connections that use unsafe
variants of the socks protocol — ones that only provide an IP address, meaning the
application is doing a DNS resolve first. Specifically, these are socks4 and socks5
when not doing remote DNS. (Default: 0)

TestSocks 0|1
When this option is enabled, Tor will make a notice-level log entry for each
connection to the Socks port indicating whether the request used a safe socks protocol
or an unsafe one (see above entry on SafeSocks). This helps to determine whether an
application using Tor is possibly leaking DNS requests. (Default: 0)

VirtualAddrNetworkIPv4 IPv4Address/bits

VirtualAddrNetworkIPv6 [IPv6Address]/bits
When Tor needs to assign a virtual (unused) address because of a MAPADDRESS command
from the controller or the AutomapHostsOnResolve feature, Tor picks an unassigned
address from this range. (Defaults: 127.192.0.0/10 and [FE80::]/10 respectively.)

When providing proxy server service to a network of computers using a tool like
dns-proxy-tor, change the IPv4 network to "10.192.0.0/10" or "172.16.0.0/12" and
change the IPv6 network to "[FC00::]/7". The default VirtualAddrNetwork address ranges
on a properly configured machine will route to the loopback or link-local interface.
The maximum number of bits for the network prefix is set to 104 for IPv6 and 16 for
IPv4. However, a wider network - smaller prefix length

• is preferable since it reduces the chances for an attacker to guess the used IP.
For local use, no change to the default VirtualAddrNetwork setting is needed.

AllowNonRFC953Hostnames 0|1
When this option is disabled, Tor blocks hostnames containing illegal characters (like
@ and :) rather than sending them to an exit node to be resolved. This helps trap
accidental attempts to resolve URLs and so on. (Default: 0)

HTTPTunnelPort [address:]port|auto [isolation flags]
Open this port to listen for proxy connections using the "HTTP CONNECT" protocol
instead of SOCKS. Set this to 0 0 if you don’t want to allow "HTTP CONNECT"
connections. Set the port to "auto" to have Tor pick a port for you. This directive
can be specified multiple times to bind to multiple addresses/ports. See SOCKSPort for
an explanation of isolation flags. (Default: 0)

TransPort [address:]port|auto [isolation flags]
Open this port to listen for transparent proxy connections. Set this to 0 if you don’t
want to allow transparent proxy connections. Set the port to "auto" to have Tor pick a
port for you. This directive can be specified multiple times to bind to multiple
addresses/ports. See SOCKSPort for an explanation of isolation flags.

TransPort requires OS support for transparent proxies, such as BSDs' pf or Linux’s
IPTables. If you’re planning to use Tor as a transparent proxy for a network, you’ll
want to examine and change VirtualAddrNetwork from the default setting. (Default: 0)

TransProxyType default|TPROXY|ipfw|pf-divert
TransProxyType may only be enabled when there is transparent proxy listener enabled.

Set this to "TPROXY" if you wish to be able to use the TPROXY Linux module to
transparently proxy connections that are configured using the TransPort option.
Detailed information on how to configure the TPROXY feature can be found in the Linux
kernel source tree in the file Documentation/networking/tproxy.txt.

Set this option to "ipfw" to use the FreeBSD ipfw interface.

On *BSD operating systems when using pf, set this to "pf-divert" to take advantage of
divert-to rules, which do not modify the packets like rdr-to rules do. Detailed
information on how to configure pf to use divert-to rules can be found in the
pf.conf(5) manual page. On OpenBSD, divert-to is available to use on versions greater
than or equal to OpenBSD 4.4.

Set this to "default", or leave it unconfigured, to use regular IPTables on Linux, or
to use pf rdr-to rules on *BSD systems.

(Default: "default".)

NATDPort [address:]port|auto [isolation flags]
Open this port to listen for connections from old versions of ipfw (as included in old
versions of FreeBSD, etc) using the NATD protocol. Use 0 if you don’t want to allow
NATD connections. Set the port to "auto" to have Tor pick a port for you. This
directive can be specified multiple times to bind to multiple addresses/ports. See
SocksPort for an explanation of isolation flags.

This option is only for people who cannot use TransPort. (Default: 0)

AutomapHostsOnResolve 0|1
When this option is enabled, and we get a request to resolve an address that ends with
one of the suffixes in AutomapHostsSuffixes, we map an unused virtual address to that
address, and return the new virtual address. This is handy for making ".onion"
addresses work with applications that resolve an address and then connect to it.
(Default: 0)

AutomapHostsSuffixes SUFFIX,SUFFIX,...
A comma-separated list of suffixes to use with AutomapHostsOnResolve. The "." suffix
is equivalent to "all addresses." (Default: .exit,.onion).

DNSPort [address:]port|auto [isolation flags]
If non-zero, open this port to listen for UDP DNS requests, and resolve them
anonymously. This port only handles A, AAAA, and PTR requests---it doesn’t handle
arbitrary DNS request types. Set the port to "auto" to have Tor pick a port for you.
This directive can be specified multiple times to bind to multiple addresses/ports.
See SocksPort for an explanation of isolation flags. (Default: 0)

ClientDNSRejectInternalAddresses 0|1
If true, Tor does not believe any anonymously retrieved DNS answer that tells it that
an address resolves to an internal address (like 127.0.0.1 or 192.168.0.1). This
option prevents certain browser-based attacks; it is not allowed to be set on the
default network. (Default: 1)

ClientRejectInternalAddresses 0|1
If true, Tor does not try to fulfill requests to connect to an internal address (like
127.0.0.1 or 192.168.0.1) unless an exit node is specifically requested (for example,
via a .exit hostname, or a controller request). If true, multicast DNS hostnames for
machines on the local network (of the form *.local) are also rejected. (Default: 1)

DownloadExtraInfo 0|1
If true, Tor downloads and caches "extra-info" documents. These documents contain
information about servers other than the information in their regular server
descriptors. Tor does not use this information for anything itself; to save bandwidth,
leave this option turned off. (Default: 0)

WarnPlaintextPorts port,port,...
Tells Tor to issue a warnings whenever the user tries to make an anonymous connection
to one of these ports. This option is designed to alert users to services that risk
sending passwords in the clear. (Default: 23,109,110,143)

RejectPlaintextPorts port,port,...
Like WarnPlaintextPorts, but instead of warning about risky port uses, Tor will
instead refuse to make the connection. (Default: None)

OptimisticData 0|1|auto
When this option is set, and Tor is using an exit node that supports the feature, it
will try optimistically to send data to the exit node without waiting for the exit
node to report whether the connection succeeded. This can save a round-trip time for
protocols like HTTP where the client talks first. If OptimisticData is set to auto,
Tor will look at the UseOptimisticData parameter in the networkstatus. (Default: auto)

Tor2webMode 0|1
When this option is set, Tor connects to hidden services non-anonymously. This option
also disables client connections to non-hidden-service hostnames through Tor. It must
only be used when running a tor2web Hidden Service web proxy. To enable this option
the compile time flag --enable-tor2web-mode must be specified. Since Tor2webMode is
non-anonymous, you can not run an anonymous Hidden Service on a tor version compiled
with Tor2webMode. (Default: 0)

Tor2webRendezvousPoints node,node,...
A list of identity fingerprints, nicknames, country codes and address patterns of
nodes that are allowed to be used as RPs in HS circuits; any other nodes will not be
used as RPs. (Example: Tor2webRendezvousPoints Fastyfasty,
ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, {cc}, 255.254.0.0/8)

This feature can only be used if Tor2webMode is also enabled.

ExcludeNodes have higher priority than Tor2webRendezvousPoints, which means that nodes
specified in ExcludeNodes will not be picked as RPs.

If no nodes in Tor2webRendezvousPoints are currently available for use, Tor will
choose a random node when building HS circuits.

UseMicrodescriptors 0|1|auto
Microdescriptors are a smaller version of the information that Tor needs in order to
build its circuits. Using microdescriptors makes Tor clients download less directory
information, thus saving bandwidth. Directory caches need to fetch regular descriptors
and microdescriptors, so this option doesn’t save any bandwidth for them. If this
option is set to "auto" (recommended) then it is on for all clients that do not set
FetchUselessDescriptors. (Default: auto)

PathBiasCircThreshold NUM

PathBiasNoticeRate NUM

PathBiasWarnRate NUM

PathBiasExtremeRate NUM

PathBiasDropGuards NUM

PathBiasScaleThreshold NUM
These options override the default behavior of Tor’s (currently experimental) path
bias detection algorithm. To try to find broken or misbehaving guard nodes, Tor looks
for nodes where more than a certain fraction of circuits through that guard fail to
get built.

The PathBiasCircThreshold option controls how many circuits we need to build through a
guard before we make these checks. The PathBiasNoticeRate, PathBiasWarnRate and
PathBiasExtremeRate options control what fraction of circuits must succeed through a
guard so we won’t write log messages. If less than PathBiasExtremeRate circuits
succeed and PathBiasDropGuards is set to 1, we disable use of that guard.

When we have seen more than PathBiasScaleThreshold circuits through a guard, we scale
our observations by 0.5 (governed by the consensus) so that new observations don’t get
swamped by old ones.

By default, or if a negative value is provided for one of these options, Tor uses
reasonable defaults from the networkstatus consensus document. If no defaults are
available there, these options default to 150, .70, .50, .30, 0, and 300 respectively.

PathBiasUseThreshold NUM

PathBiasNoticeUseRate NUM

PathBiasExtremeUseRate NUM

PathBiasScaleUseThreshold NUM
Similar to the above options, these options override the default behavior of Tor’s
(currently experimental) path use bias detection algorithm.

Where as the path bias parameters govern thresholds for successfully building
circuits, these four path use bias parameters govern thresholds only for circuit
usage. Circuits which receive no stream usage are not counted by this detection
algorithm. A used circuit is considered successful if it is capable of carrying
streams or otherwise receiving well-formed responses to RELAY cells.

ClientUseIPv4 0|1
If this option is set to 0, Tor will avoid connecting to directory servers and entry
nodes over IPv4. Note that clients with an IPv4 address in a Bridge, proxy, or
pluggable transport line will try connecting over IPv4 even if ClientUseIPv4 is set to
0. (Default: 1)

ClientUseIPv6 0|1
If this option is set to 1, Tor might connect to directory servers or entry nodes over
IPv6. Note that clients configured with an IPv6 address in a Bridge, proxy, or
pluggable transport line will try connecting over IPv6 even if ClientUseIPv6 is set to
0. (Default: 0)

ClientPreferIPv6DirPort 0|1|auto
If this option is set to 1, Tor prefers a directory port with an IPv6 address over one
with IPv4, for direct connections, if a given directory server has both. (Tor also
prefers an IPv6 DirPort if IPv4Client is set to 0.) If this option is set to auto,
clients prefer IPv4. Other things may influence the choice. This option breaks a tie
to the favor of IPv6. (Default: auto) (DEPRECATED: This option has had no effect for
some time.)

ClientPreferIPv6ORPort 0|1|auto
If this option is set to 1, Tor prefers an OR port with an IPv6 address over one with
IPv4 if a given entry node has both. (Tor also prefers an IPv6 ORPort if IPv4Client is
set to 0.) If this option is set to auto, Tor bridge clients prefer the configured
bridge address, and other clients prefer IPv4. Other things may influence the choice.
This option breaks a tie to the favor of IPv6. (Default: auto)

PathsNeededToBuildCircuits NUM
Tor clients don’t build circuits for user traffic until they know about enough of the
network so that they could potentially construct enough of the possible paths through
the network. If this option is set to a fraction between 0.25 and 0.95, Tor won’t
build circuits until it has enough descriptors or microdescriptors to construct that
fraction of possible paths. Note that setting this option too low can make your Tor
client less anonymous, and setting it too high can prevent your Tor client from
bootstrapping. If this option is negative, Tor will use a default value chosen by the
directory authorities. If the directory authorities do not choose a value, Tor will
default to 0.6. (Default: -1.)

ClientBootstrapConsensusAuthorityDownloadSchedule N,N,...
Schedule for when clients should download consensuses from authorities if they are
bootstrapping (that is, they don’t have a usable, reasonably live consensus). Only
used by clients fetching from a list of fallback directory mirrors. This schedule is
advanced by (potentially concurrent) connection attempts, unlike other schedules,
which are advanced by connection failures. (Default: 6, 11, 3600, 10800, 25200, 54000,
111600, 262800)

ClientBootstrapConsensusFallbackDownloadSchedule N,N,...
Schedule for when clients should download consensuses from fallback directory mirrors
if they are bootstrapping (that is, they don’t have a usable, reasonably live
consensus). Only used by clients fetching from a list of fallback directory mirrors.
This schedule is advanced by (potentially concurrent) connection attempts, unlike
other schedules, which are advanced by connection failures. (Default: 0, 1, 4, 11,
3600, 10800, 25200, 54000, 111600, 262800)

ClientBootstrapConsensusAuthorityOnlyDownloadSchedule N,N,...
Schedule for when clients should download consensuses from authorities if they are
bootstrapping (that is, they don’t have a usable, reasonably live consensus). Only
used by clients which don’t have or won’t fetch from a list of fallback directory
mirrors. This schedule is advanced by (potentially concurrent) connection attempts,
unlike other schedules, which are advanced by connection failures. (Default: 0, 3, 7,
3600, 10800, 25200, 54000, 111600, 262800)

ClientBootstrapConsensusMaxDownloadTries NUM
Try this many times to download a consensus while bootstrapping using fallback
directory mirrors before giving up. (Default: 7)

ClientBootstrapConsensusAuthorityOnlyMaxDownloadTries NUM
Try this many times to download a consensus while bootstrapping using authorities
before giving up. (Default: 4)

ClientBootstrapConsensusMaxInProgressTries NUM
Try this many simultaneous connections to download a consensus before waiting for one
to complete, timeout, or error out. (Default: 3)

SERVER OPTIONS

The following options are useful only for servers (that is, if ORPort is non-zero):

Address address
The IPv4 address of this server, or a fully qualified domain name of this server that
resolves to an IPv4 address. You can leave this unset, and Tor will try to guess your
IPv4 address. This IPv4 address is the one used to tell clients and other servers
where to find your Tor server; it doesn’t affect the address that your server binds
to. To bind to a different address, use the ORPort and OutboundBindAddress options.

AssumeReachable 0|1
This option is used when bootstrapping a new Tor network. If set to 1, don’t do
self-reachability testing; just upload your server descriptor immediately. If
AuthoritativeDirectory is also set, this option instructs the dirserver to bypass
remote reachability testing too and list all connected servers as running.

BridgeRelay 0|1
Sets the relay to act as a "bridge" with respect to relaying connections from bridge
users to the Tor network. It mainly causes Tor to publish a server descriptor to the
bridge database, rather than to the public directory authorities.

BridgeDistribution string
If set along with BridgeRelay, Tor will include a new line in its bridge descriptor
which indicates to the BridgeDB service how it would like its bridge address to be
given out. Set it to "none" if you want BridgeDB to avoid distributing your bridge
address, or "any" to let BridgeDB decide. (Default: any)

Note: as of Oct 2017, the BridgeDB part of this option is not yet implemented. Until
BridgeDB is updated to obey this option, your bridge will make this request, but it
will not (yet) be obeyed.

ContactInfo email_address
Administrative contact information for this relay or bridge. This line can be used to
contact you if your relay or bridge is misconfigured or something else goes wrong.
Note that we archive and publish all descriptors containing these lines and that
Google indexes them, so spammers might also collect them. You may want to obscure the
fact that it’s an email address and/or generate a new address for this purpose.

ContactInfo must be set to a working address if you run more than one relay or bridge.
(Really, everybody running a relay or bridge should set it.)

ExitRelay 0|1|auto
Tells Tor whether to run as an exit relay. If Tor is running as a non-bridge server,
and ExitRelay is set to 1, then Tor allows traffic to exit according to the ExitPolicy
option (or the default ExitPolicy if none is specified).

If ExitRelay is set to 0, no traffic is allowed to exit, and the ExitPolicy option is
ignored.

If ExitRelay is set to "auto", then Tor behaves as if it were set to 1, but warns the
user if this would cause traffic to exit. In a future version, the default value will
be 0. (Default: auto)

ExitPolicy policy,policy,...
Set an exit policy for this server. Each policy is of the form "accept[6]|reject[6]
ADDR[/MASK][:PORT]". If /MASK is omitted then this policy just applies to the host
given. Instead of giving a host or network you can also use "*" to denote the universe
(0.0.0.0/0 and ::/128), or *4 to denote all IPv4 addresses, and *6 to denote all IPv6
addresses. PORT can be a single port number, an interval of ports
"FROM_PORT-TO_PORT", or "*". If PORT is omitted, that means "*".

For example, "accept 18.7.22.69:*,reject 18.0.0.0/8:*,accept *:*" would reject any
IPv4 traffic destined for MIT except for web.mit.edu, and accept any other IPv4 or
IPv6 traffic.

Tor also allows IPv6 exit policy entries. For instance, "reject6 [FC00::]/7:*" rejects
all destinations that share 7 most significant bit prefix with address FC00::.
Respectively, "accept6 [C000::]/3:*" accepts all destinations that share 3 most
significant bit prefix with address C000::.

accept6 and reject6 only produce IPv6 exit policy entries. Using an IPv4 address with
accept6 or reject6 is ignored and generates a warning. accept/reject allows either
IPv4 or IPv6 addresses. Use *4 as an IPv4 wildcard address, and *6 as an IPv6 wildcard
address. accept/reject * expands to matching IPv4 and IPv6 wildcard address rules.

To specify all IPv4 and IPv6 internal and link-local networks (including 0.0.0.0/8,
169.254.0.0/16, 127.0.0.0/8, 192.168.0.0/16, 10.0.0.0/8, 172.16.0.0/12, [::]/8,
[FC00::]/7, [FE80::]/10, [FEC0::]/10, [FF00::]/8, and [::]/127), you can use the
"private" alias instead of an address. ("private" always produces rules for IPv4 and
IPv6 addresses, even when used with accept6/reject6.)

Private addresses are rejected by default (at the beginning of your exit policy),
along with any configured primary public IPv4 and IPv6 addresses. These private
addresses are rejected unless you set the ExitPolicyRejectPrivate config option to 0.
For example, once you’ve done that, you could allow HTTP to 127.0.0.1 and block all
other connections to internal networks with "accept 127.0.0.1:80,reject private:*",
though that may also allow connections to your own computer that are addressed to its
public (external) IP address. See RFC 1918 and RFC 3330 for more details about
internal and reserved IP address space. See ExitPolicyRejectLocalInterfaces if you
want to block every address on the relay, even those that aren’t advertised in the
descriptor.

This directive can be specified multiple times so you don’t have to put it all on one
line.

Policies are considered first to last, and the first match wins. If you want to allow
the same ports on IPv4 and IPv6, write your rules using accept/reject *. If you want
to allow different ports on IPv4 and IPv6, write your IPv6 rules using accept6/reject6
*6, and your IPv4 rules using accept/reject *4. If you want to _replace_ the default
exit policy, end your exit policy with either a reject *:* or an accept *:*.
Otherwise, you’re _augmenting_ (prepending to) the default exit policy. The default
exit policy is:

reject *:25
reject *:119
reject *:135-139
reject *:445
reject *:563
reject *:1214
reject *:4661-4666
reject *:6346-6429
reject *:6699
reject *:6881-6999
accept *:*

Since the default exit policy uses accept/reject *, it applies to both IPv4 and IPv6
addresses.

ExitPolicyRejectPrivate 0|1
Reject all private (local) networks, along with the relay’s advertised public IPv4 and
IPv6 addresses, at the beginning of your exit policy. See above entry on ExitPolicy.
(Default: 1)

ExitPolicyRejectLocalInterfaces 0|1
Reject all IPv4 and IPv6 addresses that the relay knows about, at the beginning of
your exit policy. This includes any OutboundBindAddress, the bind addresses of any
port options, such as ControlPort or DNSPort, and any public IPv4 and IPv6 addresses
on any interface on the relay. (If IPv6Exit is not set, all IPv6 addresses will be
rejected anyway.) See above entry on ExitPolicy. This option is off by default,
because it lists all public relay IP addresses in the ExitPolicy, even those relay
operators might prefer not to disclose. (Default: 0)

IPv6Exit 0|1
If set, and we are an exit node, allow clients to use us for IPv6 traffic. (Default:
0)

MaxOnionQueueDelay NUM [msec|second]
If we have more onionskins queued for processing than we can process in this amount of
time, reject new ones. (Default: 1750 msec)

MyFamily fingerprint,fingerprint,...
Declare that this Tor relay is controlled or administered by a group or organization
identical or similar to that of the other relays, defined by their (possibly
$-prefixed) identity fingerprints. This option can be repeated many times, for
convenience in defining large families: all fingerprints in all MyFamily lines are
merged into one list. When two relays both declare that they are in the same 'family',
Tor clients will not use them in the same circuit. (Each relay only needs to list the
other servers in its family; it doesn’t need to list itself, but it won’t hurt if it
does.) Do not list any bridge relay as it would compromise its concealment.

When listing a node, it’s better to list it by fingerprint than by nickname:
fingerprints are more reliable.

If you run more than one relay, the MyFamily option on each relay must list all other
relays, as described above.

Nickname name
Set the server’s nickname to 'name'. Nicknames must be between 1 and 19 characters
inclusive, and must contain only the characters [a-zA-Z0-9].

NumCPUs num
How many processes to use at once for decrypting onionskins and other parallelizable
operations. If this is set to 0, Tor will try to detect how many CPUs you have,
defaulting to 1 if it can’t tell. (Default: 0)

ORPort [address:]PORT|auto [flags]
Advertise this port to listen for connections from Tor clients and servers. This
option is required to be a Tor server. Set it to "auto" to have Tor pick a port for
you. Set it to 0 to not run an ORPort at all. This option can occur more than once.
(Default: 0)

Tor recognizes these flags on each ORPort:

NoAdvertise
By default, we bind to a port and tell our users about it. If NoAdvertise is
specified, we don’t advertise, but listen anyway. This can be useful if the port
everybody will be connecting to (for example, one that’s opened on our firewall)
is somewhere else.

NoListen
By default, we bind to a port and tell our users about it. If NoListen is
specified, we don’t bind, but advertise anyway. This can be useful if something
else (for example, a firewall’s port forwarding configuration) is causing
connections to reach us.

IPv4Only
If the address is absent, or resolves to both an IPv4 and an IPv6 address, only
listen to the IPv4 address.

IPv6Only
If the address is absent, or resolves to both an IPv4 and an IPv6 address, only
listen to the IPv6 address.

For obvious reasons, NoAdvertise and NoListen are mutually exclusive, and IPv4Only and
IPv6Only are mutually exclusive.

PortForwarding 0|1
Attempt to automatically forward the DirPort and ORPort on a NAT router connecting
this Tor server to the Internet. If set, Tor will try both NAT-PMP (common on Apple
routers) and UPnP (common on routers from other manufacturers). (Default: 0)

PortForwardingHelper filename|pathname
If PortForwarding is set, use this executable to configure the forwarding. If set to a
filename, the system path will be searched for the executable. If set to a path, only
the specified path will be executed. (Default: tor-fw-helper)

PublishServerDescriptor 0|1|v3|bridge,...
This option specifies which descriptors Tor will publish when acting as a relay. You
can choose multiple arguments, separated by commas.

If this option is set to 0, Tor will not publish its descriptors to any directories.
(This is useful if you’re testing out your server, or if you’re using a Tor controller
that handles directory publishing for you.) Otherwise, Tor will publish its
descriptors of all type(s) specified. The default is "1", which means "if running as a
relay or bridge, publish descriptors to the appropriate authorities". Other
possibilities are "v3", meaning "publish as if you’re a relay", and "bridge", meaning
"publish as if you’re a bridge".

ShutdownWaitLength NUM
When we get a SIGINT and we’re a server, we begin shutting down: we close listeners
and start refusing new circuits. After NUM seconds, we exit. If we get a second
SIGINT, we exit immediately. (Default: 30 seconds)

SSLKeyLifetime N minutes|hours|days|weeks
When creating a link certificate for our outermost SSL handshake, set its lifetime to
this amount of time. If set to 0, Tor will choose some reasonable random defaults.
(Default: 0)

HeartbeatPeriod N minutes|hours|days|weeks
Log a heartbeat message every HeartbeatPeriod seconds. This is a log level notice
message, designed to let you know your Tor server is still alive and doing useful
things. Settings this to 0 will disable the heartbeat. Otherwise, it must be at least
30 minutes. (Default: 6 hours)

AccountingMax N bytes|KBytes|MBytes|GBytes|TBytes|KBits|MBits|GBits|TBits
Limits the max number of bytes sent and received within a set time period using a
given calculation rule (see: AccountingStart, AccountingRule). Useful if you need to
stay under a specific bandwidth. By default, the number used for calculation is the
max of either the bytes sent or received. For example, with AccountingMax set to 1
GByte, a server could send 900 MBytes and receive 800 MBytes and continue running. It
will only hibernate once one of the two reaches 1 GByte. This can be changed to use
the sum of the both bytes received and sent by setting the AccountingRule option to
"sum" (total bandwidth in/out). When the number of bytes remaining gets low, Tor will
stop accepting new connections and circuits. When the number of bytes is exhausted,
Tor will hibernate until some time in the next accounting period. To prevent all
servers from waking at the same time, Tor will also wait until a random point in each
period before waking up. If you have bandwidth cost issues, enabling hibernation is
preferable to setting a low bandwidth, since it provides users with a collection of
fast servers that are up some of the time, which is more useful than a set of slow
servers that are always "available".

AccountingRule sum|max|in|out
How we determine when our AccountingMax has been reached (when we should hibernate)
during a time interval. Set to "max" to calculate using the higher of either the sent
or received bytes (this is the default functionality). Set to "sum" to calculate using
the sent plus received bytes. Set to "in" to calculate using only the received bytes.
Set to "out" to calculate using only the sent bytes. (Default: max)

AccountingStart day|week|month [day] HH:MM
Specify how long accounting periods last. If month is given, each accounting period
runs from the time HH:MM on the dayth day of one month to the same day and time of the
next. (The day must be between 1 and 28.) If week is given, each accounting period
runs from the time HH:MM of the dayth day of one week to the same day and time of the
next week, with Monday as day 1 and Sunday as day 7. If day is given, each accounting
period runs from the time HH:MM each day to the same time on the next day. All times
are local, and given in 24-hour time. (Default: "month 1 0:00")

RefuseUnknownExits 0|1|auto
Prevent nodes that don’t appear in the consensus from exiting using this relay. If the
option is 1, we always block exit attempts from such nodes; if it’s 0, we never do,
and if the option is "auto", then we do whatever the authorities suggest in the
consensus (and block if the consensus is quiet on the issue). (Default: auto)

ServerDNSResolvConfFile filename
Overrides the default DNS configuration with the configuration in filename. The file
format is the same as the standard Unix "resolv.conf" file (7). This option, like all
other ServerDNS options, only affects name lookups that your server does on behalf of
clients. (Defaults to use the system DNS configuration.)

ServerDNSAllowBrokenConfig 0|1
If this option is false, Tor exits immediately if there are problems parsing the
system DNS configuration or connecting to nameservers. Otherwise, Tor continues to
periodically retry the system nameservers until it eventually succeeds. (Default: 1)

ServerDNSSearchDomains 0|1
If set to 1, then we will search for addresses in the local search domain. For
example, if this system is configured to believe it is in "example.com", and a client
tries to connect to "www", the client will be connected to "www.example.com". This
option only affects name lookups that your server does on behalf of clients. (Default:
0)

ServerDNSDetectHijacking 0|1
When this option is set to 1, we will test periodically to determine whether our local
nameservers have been configured to hijack failing DNS requests (usually to an
advertising site). If they are, we will attempt to correct this. This option only
affects name lookups that your server does on behalf of clients. (Default: 1)

ServerDNSTestAddresses hostname,hostname,...
When we’re detecting DNS hijacking, make sure that these valid addresses aren’t
getting redirected. If they are, then our DNS is completely useless, and we’ll reset
our exit policy to "reject *:*". This option only affects name lookups that your
server does on behalf of clients. (Default: "www.google.com, www.mit.edu,
www.yahoo.com, www.slashdot.org")

ServerDNSAllowNonRFC953Hostnames 0|1
When this option is disabled, Tor does not try to resolve hostnames containing illegal
characters (like @ and :) rather than sending them to an exit node to be resolved.
This helps trap accidental attempts to resolve URLs and so on. This option only
affects name lookups that your server does on behalf of clients. (Default: 0)

BridgeRecordUsageByCountry 0|1
When this option is enabled and BridgeRelay is also enabled, and we have GeoIP data,
Tor keeps a per-country count of how many client addresses have contacted it so that
it can help the bridge authority guess which countries have blocked access to it.
(Default: 1)

ServerDNSRandomizeCase 0|1
When this option is set, Tor sets the case of each character randomly in outgoing DNS
requests, and makes sure that the case matches in DNS replies. This so-called "0x20
hack" helps resist some types of DNS poisoning attack. For more information, see
"Increased DNS Forgery Resistance through 0x20-Bit Encoding". This option only affects
name lookups that your server does on behalf of clients. (Default: 1)

GeoIPFile filename
A filename containing IPv4 GeoIP data, for use with by-country statistics.

GeoIPv6File filename
A filename containing IPv6 GeoIP data, for use with by-country statistics.

CellStatistics 0|1
Relays only. When this option is enabled, Tor collects statistics about cell
processing (i.e. mean time a cell is spending in a queue, mean number of cells in a
queue and mean number of processed cells per circuit) and writes them into disk every
24 hours. Onion router operators may use the statistics for performance monitoring. If
ExtraInfoStatistics is enabled, it will published as part of extra-info document.
(Default: 0)

PaddingStatistics 0|1
Relays only. When this option is enabled, Tor collects statistics for padding cells
sent and received by this relay, in addition to total cell counts. These statistics
are rounded, and omitted if traffic is low. This information is important for load
balancing decisions related to padding. (Default: 1)

DirReqStatistics 0|1
Relays and bridges only. When this option is enabled, a Tor directory writes
statistics on the number and response time of network status requests to disk every 24
hours. Enables relay and bridge operators to monitor how much their server is being
used by clients to learn about Tor network. If ExtraInfoStatistics is enabled, it will
published as part of extra-info document. (Default: 1)

EntryStatistics 0|1
Relays only. When this option is enabled, Tor writes statistics on the number of
directly connecting clients to disk every 24 hours. Enables relay operators to monitor
how much inbound traffic that originates from Tor clients passes through their server
to go further down the Tor network. If ExtraInfoStatistics is enabled, it will be
published as part of extra-info document. (Default: 0)

ExitPortStatistics 0|1
Exit relays only. When this option is enabled, Tor writes statistics on the number of
relayed bytes and opened stream per exit port to disk every 24 hours. Enables exit
relay operators to measure and monitor amounts of traffic that leaves Tor network
through their exit node. If ExtraInfoStatistics is enabled, it will be published as
part of extra-info document. (Default: 0)

ConnDirectionStatistics 0|1
Relays only. When this option is enabled, Tor writes statistics on the amounts of
traffic it passes between itself and other relays to disk every 24 hours. Enables
relay operators to monitor how much their relay is being used as middle node in the
circuit. If ExtraInfoStatistics is enabled, it will be published as part of extra-info
document. (Default: 0)

HiddenServiceStatistics 0|1
Relays only. When this option is enabled, a Tor relay writes obfuscated statistics on
its role as hidden-service directory, introduction point, or rendezvous point to disk
every 24 hours. If ExtraInfoStatistics is also enabled, these statistics are further
published to the directory authorities. (Default: 1)

ExtraInfoStatistics 0|1
When this option is enabled, Tor includes previously gathered statistics in its
extra-info documents that it uploads to the directory authorities. (Default: 1)

ExtendAllowPrivateAddresses 0|1
When this option is enabled, Tor will connect to relays on localhost, RFC1918
addresses, and so on. In particular, Tor will make direct OR connections, and Tor
routers allow EXTEND requests, to these private addresses. (Tor will always allow
connections to bridges, proxies, and pluggable transports configured on private
addresses.) Enabling this option can create security issues; you should probably leave
it off. (Default: 0)

MaxMemInQueues N bytes|KB|MB|GB
This option configures a threshold above which Tor will assume that it needs to stop
queueing or buffering data because it’s about to run out of memory. If it hits this
threshold, it will begin killing circuits until it has recovered at least 10% of this
memory. Do not set this option too low, or your relay may be unreliable under load.
This option only affects some queues, so the actual process size will be larger than
this. If this option is set to 0, Tor will try to pick a reasonable default based on
your system’s physical memory. (Default: 0)

DisableOOSCheck 0|1
This option disables the code that closes connections when Tor notices that it is
running low on sockets. Right now, it is on by default, since the existing
out-of-sockets mechanism tends to kill OR connections more than it should. (Default:
1)

SigningKeyLifetime N days|weeks|months
For how long should each Ed25519 signing key be valid? Tor uses a permanent master
identity key that can be kept offline, and periodically generates new "signing" keys
that it uses online. This option configures their lifetime. (Default: 30 days)

OfflineMasterKey 0|1
If non-zero, the Tor relay will never generate or load its master secret key. Instead,
you’ll have to use "tor --keygen" to manage the permanent ed25519 master identity key,
as well as the corresponding temporary signing keys and certificates. (Default: 0)

DIRECTORY SERVER OPTIONS

The following options are useful only for directory servers. (Relays with enough bandwidth
automatically become directory servers; see DirCache for details.)

DirPortFrontPage FILENAME
When this option is set, it takes an HTML file and publishes it as "/" on the DirPort.
Now relay operators can provide a disclaimer without needing to set up a separate
webserver. There’s a sample disclaimer in contrib/operator-tools/tor-exit-notice.html.

DirPort [address:]PORT|auto [flags]
If this option is nonzero, advertise the directory service on this port. Set it to
"auto" to have Tor pick a port for you. This option can occur more than once, but only
one advertised DirPort is supported: all but one DirPort must have the NoAdvertise
flag set. (Default: 0)

The same flags are supported here as are supported by ORPort.

DirPolicy policy,policy,...
Set an entrance policy for this server, to limit who can connect to the directory
ports. The policies have the same form as exit policies above, except that port
specifiers are ignored. Any address not matched by some entry in the policy is
accepted.

DirCache 0|1
When this option is set, Tor caches all current directory documents and accepts client
requests for them. Setting DirPort is not required for this, because clients connect
via the ORPort by default. Setting either DirPort or BridgeRelay and setting DirCache
to 0 is not supported. (Default: 1)

MaxConsensusAgeForDiffs N minutes|hours|days|weeks
When this option is nonzero, Tor caches will not try to generate consensus diffs for
any consensus older than this amount of time. If this option is set to zero, Tor will
pick a reasonable default from the current networkstatus document. You should not set
this option unless your cache is severely low on disk space or CPU. If you need to set
it, keeping it above 3 or 4 hours will help clients much more than setting it to zero.
(Default: 0)

DIRECTORY AUTHORITY SERVER OPTIONS

The following options enable operation as a directory authority, and control how Tor
behaves as a directory authority. You should not need to adjust any of them if you’re
running a regular relay or exit server on the public Tor network.

AuthoritativeDirectory 0|1
When this option is set to 1, Tor operates as an authoritative directory server.
Instead of caching the directory, it generates its own list of good servers, signs it,
and sends that to the clients. Unless the clients already have you listed as a trusted
directory, you probably do not want to set this option.

V3AuthoritativeDirectory 0|1
When this option is set in addition to AuthoritativeDirectory, Tor generates version 3
network statuses and serves descriptors, etc as described in dir-spec.txt file of
torspec (for Tor clients and servers running at least 0.2.0.x).

VersioningAuthoritativeDirectory 0|1
When this option is set to 1, Tor adds information on which versions of Tor are still
believed safe for use to the published directory. Each version 1 authority is
automatically a versioning authority; version 2 authorities provide this service
optionally. See RecommendedVersions, RecommendedClientVersions, and
RecommendedServerVersions.

RecommendedVersions STRING
STRING is a comma-separated list of Tor versions currently believed to be safe. The
list is included in each directory, and nodes which pull down the directory learn
whether they need to upgrade. This option can appear multiple times: the values from
multiple lines are spliced together. When this is set then
VersioningAuthoritativeDirectory should be set too.

RecommendedPackages PACKAGENAME VERSION URL DIGESTTYPE=DIGEST
Adds "package" line to the directory authority’s vote. This information is used to
vote on the correct URL and digest for the released versions of different Tor-related
packages, so that the consensus can certify them. This line may appear any number of
times.

RecommendedClientVersions STRING
STRING is a comma-separated list of Tor versions currently believed to be safe for
clients to use. This information is included in version 2 directories. If this is not
set then the value of RecommendedVersions is used. When this is set then
VersioningAuthoritativeDirectory should be set too.

BridgeAuthoritativeDir 0|1
When this option is set in addition to AuthoritativeDirectory, Tor accepts and serves
server descriptors, but it caches and serves the main networkstatus documents rather
than generating its own. (Default: 0)

MinUptimeHidServDirectoryV2 N seconds|minutes|hours|days|weeks
Minimum uptime of a v2 hidden service directory to be accepted as such by
authoritative directories. (Default: 25 hours)

RecommendedServerVersions STRING
STRING is a comma-separated list of Tor versions currently believed to be safe for
servers to use. This information is included in version 2 directories. If this is not
set then the value of RecommendedVersions is used. When this is set then
VersioningAuthoritativeDirectory should be set too.

ConsensusParams STRING
STRING is a space-separated list of key=value pairs that Tor will include in the
"params" line of its networkstatus vote.

DirAllowPrivateAddresses 0|1
If set to 1, Tor will accept server descriptors with arbitrary "Address" elements.
Otherwise, if the address is not an IP address or is a private IP address, it will
reject the server descriptor. Additionally, Tor will allow exit policies for private
networks to fulfill Exit flag requirements. (Default: 0)

AuthDirBadExit AddressPattern...
Authoritative directories only. A set of address patterns for servers that will be
listed as bad exits in any network status document this authority publishes, if
AuthDirListBadExits is set.

(The address pattern syntax here and in the options below is the same as for exit
policies, except that you don’t need to say "accept" or "reject", and ports are not
needed.)

AuthDirInvalid AddressPattern...
Authoritative directories only. A set of address patterns for servers that will never
be listed as "valid" in any network status document that this authority publishes.

AuthDirReject AddressPattern...
Authoritative directories only. A set of address patterns for servers that will never
be listed at all in any network status document that this authority publishes, or
accepted as an OR address in any descriptor submitted for publication by this
authority.

AuthDirBadExitCCs CC,...

AuthDirInvalidCCs CC,...

AuthDirRejectCCs CC,...
Authoritative directories only. These options contain a comma-separated list of
country codes such that any server in one of those country codes will be marked as a
bad exit/invalid for use, or rejected entirely.

AuthDirListBadExits 0|1
Authoritative directories only. If set to 1, this directory has some opinion about
which nodes are unsuitable as exit nodes. (Do not set this to 1 unless you plan to
list non-functioning exits as bad; otherwise, you are effectively voting in favor of
every declared exit as an exit.)

AuthDirMaxServersPerAddr NUM
Authoritative directories only. The maximum number of servers that we will list as
acceptable on a single IP address. Set this to "0" for "no limit". (Default: 2)

AuthDirPinKeys 0|1
Authoritative directories only. If non-zero, do not allow any relay to publish a
descriptor if any other relay has reserved its <Ed25519,RSA> identity keypair. In all
cases, Tor records every keypair it accepts in a journal if it is new, or if it
differs from the most recently accepted pinning for one of the keys it contains.
(Default: 1)

AuthDirSharedRandomness 0|1
Authoritative directories only. Switch for the shared random protocol. If zero, the
authority won’t participate in the protocol. If non-zero (default), the flag
"shared-rand-participate" is added to the authority vote indicating participation in
the protocol. (Default: 1)

AuthDirTestEd25519LinkKeys 0|1
Authoritative directories only. If this option is set to 0, then we treat relays as
"Running" if their RSA key is correct when we probe them, regardless of their Ed25519
key. We should only ever set this option to 0 if there is some major bug in Ed25519
link authentication that causes us to label all the relays as not Running. (Default:
1)

BridgePassword Password
If set, contains an HTTP authenticator that tells a bridge authority to serve all
requested bridge information. Used by the (only partially implemented) "bridge
community" design, where a community of bridge relay operators all use an alternate
bridge directory authority, and their target user audience can periodically fetch the
list of available community bridges to stay up-to-date. (Default: not set)

V3AuthVotingInterval N minutes|hours
V3 authoritative directories only. Configures the server’s preferred voting interval.
Note that voting will actually happen at an interval chosen by consensus from all the
authorities' preferred intervals. This time SHOULD divide evenly into a day. (Default:
1 hour)

V3AuthVoteDelay N minutes|hours
V3 authoritative directories only. Configures the server’s preferred delay between
publishing its vote and assuming it has all the votes from all the other authorities.
Note that the actual time used is not the server’s preferred time, but the consensus
of all preferences. (Default: 5 minutes)

V3AuthDistDelay N minutes|hours
V3 authoritative directories only. Configures the server’s preferred delay between
publishing its consensus and signature and assuming it has all the signatures from all
the other authorities. Note that the actual time used is not the server’s preferred
time, but the consensus of all preferences. (Default: 5 minutes)

V3AuthNIntervalsValid NUM
V3 authoritative directories only. Configures the number of VotingIntervals for which
each consensus should be valid for. Choosing high numbers increases network
partitioning risks; choosing low numbers increases directory traffic. Note that the
actual number of intervals used is not the server’s preferred number, but the
consensus of all preferences. Must be at least 2. (Default: 3)

V3BandwidthsFile FILENAME
V3 authoritative directories only. Configures the location of the bandwidth-authority
generated file storing information on relays' measured bandwidth capacities. (Default:
unset)

V3AuthUseLegacyKey 0|1
If set, the directory authority will sign consensuses not only with its own signing
key, but also with a "legacy" key and certificate with a different identity. This
feature is used to migrate directory authority keys in the event of a compromise.
(Default: 0)

RephistTrackTime N seconds|minutes|hours|days|weeks
Tells an authority, or other node tracking node reliability and history, that
fine-grained information about nodes can be discarded when it hasn’t changed for a
given amount of time. (Default: 24 hours)

AuthDirHasIPv6Connectivity 0|1
Authoritative directories only. When set to 0, OR ports with an IPv6 address are being
accepted without reachability testing. When set to 1, IPv6 OR ports are being tested
just like IPv4 OR ports. (Default: 0)

MinMeasuredBWsForAuthToIgnoreAdvertised N
A total value, in abstract bandwidth units, describing how much measured total
bandwidth an authority should have observed on the network before it will treat
advertised bandwidths as wholly unreliable. (Default: 500)

HIDDEN SERVICE OPTIONS

The following options are used to configure a hidden service.

HiddenServiceDir DIRECTORY
Store data files for a hidden service in DIRECTORY. Every hidden service must have a
separate directory. You may use this option multiple times to specify multiple
services. If DIRECTORY does not exist, Tor will create it. (Note: in current versions
of Tor, if DIRECTORY is a relative path, it will be relative to the current working
directory of Tor instance, not to its DataDirectory. Do not rely on this behavior; it
is not guaranteed to remain the same in future versions.)

HiddenServicePort VIRTPORT [TARGET]
Configure a virtual port VIRTPORT for a hidden service. You may use this option
multiple times; each time applies to the service using the most recent
HiddenServiceDir. By default, this option maps the virtual port to the same port on
127.0.0.1 over TCP. You may override the target port, address, or both by specifying a
target of addr, port, addr:port, or unix:path. (You can specify an IPv6 target as
[addr]:port. Unix paths may be quoted, and may use standard C escapes.) You may also
have multiple lines with the same VIRTPORT: when a user connects to that VIRTPORT, one
of the TARGETs from those lines will be chosen at random.

PublishHidServDescriptors 0|1
If set to 0, Tor will run any hidden services you configure, but it won’t advertise
them to the rendezvous directory. This option is only useful if you’re using a Tor
controller that handles hidserv publishing for you. (Default: 1)

HiddenServiceVersion version,version,...
A list of rendezvous service descriptor versions to publish for the hidden service.
Currently, versions 2 and 3 are supported. (Default: 2)

HiddenServiceAuthorizeClient auth-type client-name,client-name,...
If configured, the hidden service is accessible for authorized clients only. The
auth-type can either be 'basic' for a general-purpose authorization protocol or
'stealth' for a less scalable protocol that also hides service activity from
unauthorized clients. Only clients that are listed here are authorized to access the
hidden service. Valid client names are 1 to 16 characters long and only use characters
in A-Za-z0-9+-_ (no spaces). If this option is set, the hidden service is not
accessible for clients without authorization any more. Generated authorization data
can be found in the hostname file. Clients need to put this authorization data in
their configuration file using HidServAuth.

HiddenServiceAllowUnknownPorts 0|1
If set to 1, then connections to unrecognized ports do not cause the current hidden
service to close rendezvous circuits. (Setting this to 0 is not an authorization
mechanism; it is instead meant to be a mild inconvenience to port-scanners.) (Default:
0)

HiddenServiceMaxStreams N
The maximum number of simultaneous streams (connections) per rendezvous circuit. The
maximum value allowed is 65535. (Setting this to 0 will allow an unlimited number of
simultanous streams.) (Default: 0)

HiddenServiceMaxStreamsCloseCircuit 0|1
If set to 1, then exceeding HiddenServiceMaxStreams will cause the offending
rendezvous circuit to be torn down, as opposed to stream creation requests that exceed
the limit being silently ignored. (Default: 0)

RendPostPeriod N seconds|minutes|hours|days|weeks
Every time the specified period elapses, Tor uploads any rendezvous service
descriptors to the directory servers. This information is also uploaded whenever it
changes. Minimum value allowed is 10 minutes and maximum is 3.5 days. (Default: 1
hour)

HiddenServiceDirGroupReadable 0|1
If this option is set to 1, allow the filesystem group to read the hidden service
directory and hostname file. If the option is set to 0, only owner is able to read the
hidden service directory. (Default: 0) Has no effect on Windows.

HiddenServiceNumIntroductionPoints NUM
Number of introduction points the hidden service will have. You can’t have more than
10 for v2 service and 20 for v3. (Default: 3)

HiddenServiceSingleHopMode 0|1
Experimental - Non Anonymous Hidden Services on a tor instance in
HiddenServiceSingleHopMode make one-hop (direct) circuits between the onion service
server, and the introduction and rendezvous points. (Onion service descriptors are
still posted using 3-hop paths, to avoid onion service directories blocking the
service.) This option makes every hidden service instance hosted by a tor instance a
Single Onion Service. One-hop circuits make Single Onion servers easily locatable, but
clients remain location-anonymous. However, the fact that a client is accessing a
Single Onion rather than a Hidden Service may be statistically distinguishable.

WARNING: Once a hidden service directory has been used by a tor instance in
HiddenServiceSingleHopMode, it can NEVER be used again for a hidden service. It is
best practice to create a new hidden service directory, key, and address for each new
Single Onion Service and Hidden Service. It is not possible to run Single Onion
Services and Hidden Services from the same tor instance: they should be run on
different servers with different IP addresses.

HiddenServiceSingleHopMode requires HiddenServiceNonAnonymousMode to be set to 1.
Since a Single Onion service is non-anonymous, you can not configure a SOCKSPort on a
tor instance that is running in HiddenServiceSingleHopMode. Can not be changed while
tor is running. (Default: 0)

HiddenServiceNonAnonymousMode 0|1
Makes hidden services non-anonymous on this tor instance. Allows the non-anonymous
HiddenServiceSingleHopMode. Enables direct connections in the server-side hidden
service protocol. If you are using this option, you need to disable all client-side
services on your Tor instance, including setting SOCKSPort to "0". Can not be changed
while tor is running. (Default: 0)

DENIAL OF SERVICE MITIGATION OPTIONS

The following options are useful only for a public relay. They control the Denial of
Service mitigation subsystem.

DoSCircuitCreationEnabled 0|1|auto
Enable circuit creation DoS mitigation. If enabled, tor will cache client IPs along
with statistics in order to detect circuit DoS attacks. If an address is positively
identified, tor will activate defenses against the address. See the
DoSCircuitCreationDefenseType option for more details. This is a client to relay
detection only. "auto" means use the consensus parameter. If not defined in the
consensus, the value is 0. (Default: auto)

DoSCircuitCreationMinConnections NUM
Minimum threshold of concurrent connections before a client address can be flagged as
executing a circuit creation DoS. In other words, once a client address reaches the
circuit rate and has a minimum of NUM concurrent connections, a detection is positive.
"0" means use the consensus parameter. If not defined in the consensus, the value is
3. (Default: 0)

DoSCircuitCreationRate NUM
The allowed circuit creation rate per second applied per client IP address. If this
option is 0, it obeys a consensus parameter. If not defined in the consensus, the
value is 3. (Default: 0)

DoSCircuitCreationBurst NUM
The allowed circuit creation burst per client IP address. If the circuit rate and the
burst are reached, a client is marked as executing a circuit creation DoS. "0" means
use the consensus parameter. If not defined in the consensus, the value is 90.
(Default: 0)

DoSCircuitCreationDefenseType NUM
This is the type of defense applied to a detected client address. The possible values
are:

1: No defense.
2: Refuse circuit creation for the DoSCircuitCreationDefenseTimePeriod period of time.

"0" means use the consensus parameter. If not defined in the consensus,
the value is 2.
(Default: 0)

DoSCircuitCreationDefenseTimePeriod N seconds|minutes|hours
The base time period in seconds that the DoS defense is activated for. The actual
value is selected randomly for each activation from N+1 to 3/2 * N. "0" means use the
consensus parameter. If not defined in the consensus, the value is 3600 seconds (1
hour). (Default: 0)

DoSConnectionEnabled 0|1|auto
Enable the connection DoS mitigation. For client address only, this allows tor to
mitigate against large number of concurrent connections made by a single IP address.
"auto" means use the consensus parameter. If not defined in the consensus, the value
is 0. (Default: auto)

DoSConnectionMaxConcurrentCount NUM
The maximum threshold of concurrent connection from a client IP address. Above this
limit, a defense selected by DoSConnectionDefenseType is applied. "0" means use the
consensus parameter. If not defined in the consensus, the value is 100. (Default: 0)

DoSConnectionDefenseType NUM
This is the type of defense applied to a detected client address for the connection
mitigation. The possible values are:

1: No defense.
2: Immediately close new connections.

"0" means use the consensus parameter. If not defined in the consensus,
the value is 2.
(Default: 0)

DoSRefuseSingleHopClientRendezvous 0|1|auto
Refuse establishment of rendezvous points for single hop clients. In other words, if a
client directly connects to the relay and sends an ESTABLISH_RENDEZVOUS cell, it is
silently dropped. "auto" means use the consensus parameter. If not defined in the
consensus, the value is 0. (Default: auto)

TESTING NETWORK OPTIONS

The following options are used for running a testing Tor network.

TestingTorNetwork 0|1
If set to 1, Tor adjusts default values of the configuration options below, so that it
is easier to set up a testing Tor network. May only be set if non-default set of
DirAuthorities is set. Cannot be unset while Tor is running. (Default: 0)

ServerDNSAllowBrokenConfig 1
DirAllowPrivateAddresses 1
EnforceDistinctSubnets 0
AssumeReachable 1
AuthDirMaxServersPerAddr 0
AuthDirMaxServersPerAuthAddr 0
ClientBootstrapConsensusAuthorityDownloadSchedule 0, 2,
4 (for 40 seconds), 8, 16, 32, 60
ClientBootstrapConsensusFallbackDownloadSchedule 0, 1,
4 (for 40 seconds), 8, 16, 32, 60
ClientBootstrapConsensusAuthorityOnlyDownloadSchedule 0, 1,
4 (for 40 seconds), 8, 16, 32, 60
ClientBootstrapConsensusMaxDownloadTries 80
ClientBootstrapConsensusAuthorityOnlyMaxDownloadTries 80
ClientDNSRejectInternalAddresses 0
ClientRejectInternalAddresses 0
CountPrivateBandwidth 1
ExitPolicyRejectPrivate 0
ExtendAllowPrivateAddresses 1
V3AuthVotingInterval 5 minutes
V3AuthVoteDelay 20 seconds
V3AuthDistDelay 20 seconds
MinUptimeHidServDirectoryV2 0 seconds
TestingV3AuthInitialVotingInterval 5 minutes
TestingV3AuthInitialVoteDelay 20 seconds
TestingV3AuthInitialDistDelay 20 seconds
TestingAuthDirTimeToLearnReachability 0 minutes
TestingEstimatedDescriptorPropagationTime 0 minutes
TestingServerDownloadSchedule 0, 0, 0, 5, 10, 15, 20, 30, 60
TestingClientDownloadSchedule 0, 0, 5, 10, 15, 20, 30, 60
TestingServerConsensusDownloadSchedule 0, 0, 5, 10, 15, 20, 30, 60
TestingClientConsensusDownloadSchedule 0, 0, 5, 10, 15, 20, 30, 60
TestingBridgeDownloadSchedule 10, 30, 60
TestingBridgeBootstrapDownloadSchedule 0, 0, 5, 10, 15, 20, 30, 60
TestingClientMaxIntervalWithoutRequest 5 seconds
TestingDirConnectionMaxStall 30 seconds
TestingConsensusMaxDownloadTries 80
TestingDescriptorMaxDownloadTries 80
TestingMicrodescMaxDownloadTries 80
TestingCertMaxDownloadTries 80
TestingEnableConnBwEvent 1
TestingEnableCellStatsEvent 1
TestingEnableTbEmptyEvent 1

TestingV3AuthInitialVotingInterval N minutes|hours
Like V3AuthVotingInterval, but for initial voting interval before the first consensus
has been created. Changing this requires that TestingTorNetwork is set. (Default: 30
minutes)

TestingV3AuthInitialVoteDelay N minutes|hours
Like V3AuthVoteDelay, but for initial voting interval before the first consensus has
been created. Changing this requires that TestingTorNetwork is set. (Default: 5
minutes)

TestingV3AuthInitialDistDelay N minutes|hours
Like V3AuthDistDelay, but for initial voting interval before the first consensus has
been created. Changing this requires that TestingTorNetwork is set. (Default: 5
minutes)

TestingV3AuthVotingStartOffset N seconds|minutes|hours
Directory authorities offset voting start time by this much. Changing this requires
that TestingTorNetwork is set. (Default: 0)

TestingAuthDirTimeToLearnReachability N minutes|hours
After starting as an authority, do not make claims about whether routers are Running
until this much time has passed. Changing this requires that TestingTorNetwork is set.
(Default: 30 minutes)

TestingEstimatedDescriptorPropagationTime N minutes|hours
Clients try downloading server descriptors from directory caches after this time.
Changing this requires that TestingTorNetwork is set. (Default: 10 minutes)

TestingServerDownloadSchedule N,N,...
Schedule for when servers should download things in general. Changing this requires
that TestingTorNetwork is set. (Default: 0, 0, 0, 60, 60, 120, 300, 900, 2147483647)

TestingClientDownloadSchedule N,N,...
Schedule for when clients should download things in general. Changing this requires
that TestingTorNetwork is set. (Default: 0, 0, 60, 300, 600, 2147483647)

TestingServerConsensusDownloadSchedule N,N,...
Schedule for when servers should download consensuses. Changing this requires that
TestingTorNetwork is set. (Default: 0, 0, 60, 300, 600, 1800, 1800, 1800, 1800, 1800,
3600, 7200)

TestingClientConsensusDownloadSchedule N,N,...
Schedule for when clients should download consensuses. Changing this requires that
TestingTorNetwork is set. (Default: 0, 0, 60, 300, 600, 1800, 3600, 3600, 3600, 10800,
21600, 43200)

TestingBridgeDownloadSchedule N,N,...
Schedule for when clients should download each bridge descriptor when they know that
one or more of their configured bridges are running. Changing this requires that
TestingTorNetwork is set. (Default: 10800, 25200, 54000, 111600, 262800)

TestingBridgeBootstrapDownloadSchedule N,N,...
Schedule for when clients should download each bridge descriptor when they have just
started, or when they can not contact any of their bridges. Changing this requires
that TestingTorNetwork is set. (Default: 0, 30, 90, 600, 3600, 10800, 25200, 54000,
111600, 262800)

TestingClientMaxIntervalWithoutRequest N seconds|minutes
When directory clients have only a few descriptors to request, they batch them until
they have more, or until this amount of time has passed. Changing this requires that
TestingTorNetwork is set. (Default: 10 minutes)

TestingDirConnectionMaxStall N seconds|minutes
Let a directory connection stall this long before expiring it. Changing this requires
that TestingTorNetwork is set. (Default: 5 minutes)

TestingConsensusMaxDownloadTries NUM
Try this many times to download a consensus before giving up. Changing this requires
that TestingTorNetwork is set. (Default: 8)

TestingDescriptorMaxDownloadTries NUM
Try this often to download a server descriptor before giving up. Changing this
requires that TestingTorNetwork is set. (Default: 8)

TestingMicrodescMaxDownloadTries NUM
Try this often to download a microdesc descriptor before giving up. Changing this
requires that TestingTorNetwork is set. (Default: 8)

TestingCertMaxDownloadTries NUM
Try this often to download a v3 authority certificate before giving up. Changing this
requires that TestingTorNetwork is set. (Default: 8)

TestingDirAuthVoteExit node,node,...
A list of identity fingerprints, country codes, and address patterns of nodes to vote
Exit for regardless of their uptime, bandwidth, or exit policy. See the ExcludeNodes
option for more information on how to specify nodes.

In order for this option to have any effect, TestingTorNetwork has to be set. See the
ExcludeNodes option for more information on how to specify nodes.

TestingDirAuthVoteExitIsStrict 0|1
If True (1), a node will never receive the Exit flag unless it is specified in the
TestingDirAuthVoteExit list, regardless of its uptime, bandwidth, or exit policy.

In order for this option to have any effect, TestingTorNetwork has to be set.

TestingDirAuthVoteGuard node,node,...
A list of identity fingerprints and country codes and address patterns of nodes to
vote Guard for regardless of their uptime and bandwidth. See the ExcludeNodes option
for more information on how to specify nodes.

In order for this option to have any effect, TestingTorNetwork has to be set.

TestingDirAuthVoteGuardIsStrict 0|1
If True (1), a node will never receive the Guard flag unless it is specified in the
TestingDirAuthVoteGuard list, regardless of its uptime and bandwidth.

In order for this option to have any effect, TestingTorNetwork has to be set.

TestingDirAuthVoteHSDir node,node,...
A list of identity fingerprints and country codes and address patterns of nodes to
vote HSDir for regardless of their uptime and DirPort. See the ExcludeNodes option for
more information on how to specify nodes.

In order for this option to have any effect, TestingTorNetwork must be set.

TestingDirAuthVoteHSDirIsStrict 0|1
If True (1), a node will never receive the HSDir flag unless it is specified in the
TestingDirAuthVoteHSDir list, regardless of its uptime and DirPort.

In order for this option to have any effect, TestingTorNetwork has to be set.

TestingEnableConnBwEvent 0|1
If this option is set, then Tor controllers may register for CONN_BW events. Changing
this requires that TestingTorNetwork is set. (Default: 0)

TestingEnableCellStatsEvent 0|1
If this option is set, then Tor controllers may register for CELL_STATS events.
Changing this requires that TestingTorNetwork is set. (Default: 0)

TestingEnableTbEmptyEvent 0|1
If this option is set, then Tor controllers may register for TB_EMPTY events. Changing
this requires that TestingTorNetwork is set. (Default: 0)

TestingLinkKeySlop N seconds|minutes|hours

TestingAuthKeySlop N seconds|minutes|hours

TestingSigningKeySlop N seconds|minutes|hours
How early before the official expiration of a an Ed25519 signing key do we replace it
and issue a new key? (Default: 3 hours for link and auth; 1 day for signing.)

NON-PERSISTENT OPTIONS

       These options are not saved to the torrc file by the "SAVECONF" controller command. Other
       options of this type are documented in control-spec.txt, section 5.4. End-users should
       mostly ignore them.

       __ControlPort, __DirPort, __DNSPort, __ExtORPort, __NATDPort, __ORPort, __SocksPort,
       \_\_TransPort
           These underscore-prefixed options are variants of the regular Port options. They
           behave the same, except they are not saved to the torrc file by the controller’s
           SAVECONF command.

SIGNALS

       Tor catches the following signals:

       SIGTERM
           Tor will catch this, clean up and sync to disk if necessary, and exit.

       SIGINT
           Tor clients behave as with SIGTERM; but Tor servers will do a controlled slow
           shutdown, closing listeners and waiting 30 seconds before exiting. (The delay can be
           configured with the ShutdownWaitLength config option.)

       SIGHUP
           The signal instructs Tor to reload its configuration (including closing and reopening
           logs), and kill and restart its helper processes if applicable.

       SIGUSR1
           Log statistics about current connections, past connections, and throughput.

       SIGUSR2
           Switch all logs to loglevel debug. You can go back to the old loglevels by sending a
           SIGHUP.

       SIGCHLD
           Tor receives this signal when one of its helper processes has exited, so it can clean
           up.

       SIGPIPE
           Tor catches this signal and ignores it.

       SIGXFSZ
           If this signal exists on your platform, Tor catches and ignores it.

FILES

/etc/tor/torrc
The configuration file, which contains "option value" pairs.

$HOME/.torrc
Fallback location for torrc, if /etc/tor/torrc is not found.

/var/lib/tor/
The tor process stores keys and other data here.

DataDirectory/cached-status/
The most recently downloaded network status document for each authority. Each file
holds one such document; the filenames are the hexadecimal identity key fingerprints
of the directory authorities. Obsolete; no longer in use.

DataDirectory/cached-certs
This file holds downloaded directory key certificates that are used to verify
authenticity of documents generated by Tor directory authorities.

DataDirectory/cached-consensus and/or cached-microdesc-consensus
The most recent consensus network status document we’ve downloaded.

DataDirectory/cached-descriptors and cached-descriptors.new
These files hold downloaded router statuses. Some routers may appear more than once;
if so, the most recently published descriptor is used. Lines beginning with @-signs
are annotations that contain more information about a given router. The ".new" file is
an append-only journal; when it gets too large, all entries are merged into a new
cached-descriptors file.

DataDirectory/cached-extrainfo and cached-extrainfo.new
As "cached-descriptors", but holds optionally-downloaded "extra-info" documents.
Relays use these documents to send inessential information about statistics, bandwidth
history, and network health to the authorities. They aren’t fetched by default; see
the DownloadExtraInfo option for more info.

DataDirectory/cached-microdescs and cached-microdescs.new
These files hold downloaded microdescriptors. Lines beginning with @-signs are
annotations that contain more information about a given router. The ".new" file is an
append-only journal; when it gets too large, all entries are merged into a new
cached-microdescs file.

DataDirectory/cached-routers and cached-routers.new
Obsolete versions of cached-descriptors and cached-descriptors.new. When Tor can’t
find the newer files, it looks here instead.

DataDirectory/state
A set of persistent key-value mappings. These are documented in the file. These
include:

• The current entry guards and their status.

• The current bandwidth accounting values.

• When the file was last written

• What version of Tor generated the state file

• A short history of bandwidth usage, as produced in the server descriptors.

DataDirectory/sr-state
Authority only. State file used to record information about the current status of the
shared-random-value voting state.

DataDirectory/diff-cache
Directory cache only. Holds older consensuses, and diffs from older consensuses to the
most recent consensus of each type, compressed in various ways. Each file contains a
set of key-value arguments decribing its contents, followed by a single NUL byte,
followed by the main file contents.

DataDirectory/bw_accounting
Used to track bandwidth accounting values (when the current period starts and ends;
how much has been read and written so far this period). This file is obsolete, and the
data is now stored in the 'state' file instead.

DataDirectory/control_auth_cookie
Used for cookie authentication with the controller. Location can be overridden by the
CookieAuthFile config option. Regenerated on startup. See control-spec.txt in torspec
for details. Only used when cookie authentication is enabled.

DataDirectory/lock
This file is used to prevent two Tor instances from using same data directory. If
access to this file is locked, data directory is already in use by Tor.

DataDirectory/key-pinning-journal
Used by authorities. A line-based file that records mappings between RSA1024 identity
keys and Ed25519 identity keys. Authorities enforce these mappings, so that once a
relay has picked an Ed25519 key, stealing or factoring the RSA1024 key will no longer
let an attacker impersonate the relay.

DataDirectory/keys/*
Only used by servers. Holds identity keys and onion keys.

DataDirectory/keys/authority_identity_key
A v3 directory authority’s master identity key, used to authenticate its signing key.
Tor doesn’t use this while it’s running. The tor-gencert program uses this. If you’re
running an authority, you should keep this key offline, and not actually put it here.

DataDirectory/keys/authority_certificate
A v3 directory authority’s certificate, which authenticates the authority’s current
vote- and consensus-signing key using its master identity key. Only directory
authorities use this file.

DataDirectory/keys/authority_signing_key
A v3 directory authority’s signing key, used to sign votes and consensuses. Only
directory authorities use this file. Corresponds to the authority_certificate cert.

DataDirectory/keys/legacy_certificate
As authority_certificate: used only when V3AuthUseLegacyKey is set. See documentation
for V3AuthUseLegacyKey.

DataDirectory/keys/legacy_signing_key
As authority_signing_key: used only when V3AuthUseLegacyKey is set. See documentation
for V3AuthUseLegacyKey.

DataDirectory/keys/secret_id_key
A relay’s RSA1024 permanent identity key, including private and public components.
Used to sign router descriptors, and to sign other keys.

DataDirectory/keys/ed25519_master_id_public_key
The public part of a relay’s Ed25519 permanent identity key.

DataDirectory/keys/ed25519_master_id_secret_key
The private part of a relay’s Ed25519 permanent identity key. This key is used to sign
the medium-term ed25519 signing key. This file can be kept offline, or kept encrypted.
If so, Tor will not be able to generate new signing keys itself; you’ll need to use
tor --keygen yourself to do so.

DataDirectory/keys/ed25519_signing_secret_key
The private and public components of a relay’s medium-term Ed25519 signing key. This
key is authenticated by the Ed25519 master key, in turn authenticates other keys (and
router descriptors).

DataDirectory/keys/ed25519_signing_cert
The certificate which authenticates "ed25519_signing_secret_key" as having been signed
by the Ed25519 master key.

DataDirectory/keys/secret_onion_key and secret_onion_key.old
A relay’s RSA1024 short-term onion key. Used to decrypt old-style ("TAP") circuit
extension requests. The ".old" file holds the previously generated key, which the
relay uses to handle any requests that were made by clients that didn’t have the new
one.

DataDirectory/keys/secret_onion_key_ntor and secret_onion_key_ntor.old
A relay’s Curve25519 short-term onion key. Used to handle modern ("ntor") circuit
extension requests. The ".old" file holds the previously generated key, which the
relay uses to handle any requests that were made by clients that didn’t have the new
one.

DataDirectory/fingerprint
Only used by servers. Holds the fingerprint of the server’s identity key.

DataDirectory/hashed-fingerprint
Only used by bridges. Holds the hashed fingerprint of the bridge’s identity key. (That
is, the hash of the hash of the identity key.)

DataDirectory/approved-routers
Only used by authoritative directory servers. This file lists the status of routers by
their identity fingerprint. Each line lists a status and a fingerprint separated by
whitespace. See your fingerprint file in the DataDirectory for an example line. If the
status is !reject then descriptors from the given identity (fingerprint) are rejected
by this server. If it is !invalid then descriptors are accepted but marked in the
directory as not valid, that is, not recommended.

DataDirectory/v3-status-votes
Only for v3 authoritative directory servers. This file contains status votes from all
the authoritative directory servers.

DataDirectory/unverified-consensus
This file contains a network consensus document that has been downloaded, but which we
didn’t have the right certificates to check yet.

DataDirectory/unverified-microdesc-consensus
This file contains a microdescriptor-flavored network consensus document that has been
downloaded, but which we didn’t have the right certificates to check yet.

DataDirectory/unparseable-desc
Onion server descriptors that Tor was unable to parse are dumped to this file. Only
used for debugging.

DataDirectory/router-stability
Only used by authoritative directory servers. Tracks measurements for router
mean-time-between-failures so that authorities have a good idea of how to set their
Stable flags.

DataDirectory/stats/dirreq-stats
Only used by directory caches and authorities. This file is used to collect directory
request statistics.

DataDirectory/stats/entry-stats
Only used by servers. This file is used to collect incoming connection statistics by
Tor entry nodes.

DataDirectory/stats/bridge-stats
Only used by servers. This file is used to collect incoming connection statistics by
Tor bridges.

DataDirectory/stats/exit-stats
Only used by servers. This file is used to collect outgoing connection statistics by
Tor exit routers.

DataDirectory/stats/buffer-stats
Only used by servers. This file is used to collect buffer usage history.

DataDirectory/stats/conn-stats
Only used by servers. This file is used to collect approximate connection history
(number of active connections over time).

DataDirectory/stats/hidserv-stats
Only used by servers. This file is used to collect approximate counts of what fraction
of the traffic is hidden service rendezvous traffic, and approximately how many hidden
services the relay has seen.

DataDirectory/networkstatus-bridges
Only used by authoritative bridge directories. Contains information about bridges that
have self-reported themselves to the bridge authority.

DataDirectory/approved-routers
Authorities only. This file is used to configure which relays are known to be valid,
invalid, and so forth.

HiddenServiceDirectory/hostname
The <base32-encoded-fingerprint>.onion domain name for this hidden service. If the
hidden service is restricted to authorized clients only, this file also contains
authorization data for all clients.

Note that clients will ignore any extra subdomains prepended to a hidden service
hostname. So if you have "xyz.onion" as your hostname, you can tell clients to connect
to "www.xyz.onion" or "irc.xyz.onion" for virtual-hosting purposes.

HiddenServiceDirectory/private_key
The private key for this hidden service.

HiddenServiceDirectory/client_keys
Authorization data for a hidden service that is only accessible by authorized clients.

HiddenServiceDirectory/onion_service_non_anonymous
This file is present if a hidden service key was created in
HiddenServiceNonAnonymousMode.

BUGS

       Plenty, probably. Tor is still in development. Please report them at
       https://trac.torproject.org/.

AUTHORS

       Roger Dingledine [arma at mit.edu], Nick Mathewson [nickm at alum.mit.edu].

NAME

SYNOPSIS

DESCRIPTION

COMMAND-LINE OPTIONS

THE CONFIGURATION FILE FORMAT

GENERAL OPTIONS

CLIENT OPTIONS

SERVER OPTIONS

DIRECTORY SERVER OPTIONS

DIRECTORY AUTHORITY SERVER OPTIONS

HIDDEN SERVICE OPTIONS

DENIAL OF SERVICE MITIGATION OPTIONS

TESTING NETWORK OPTIONS

NON-PERSISTENT OPTIONS

SIGNALS

FILES

SEE ALSO

BUGS

AUTHORS