Provided by: gvpe_2.24-1_i386
gvpe.conf - configuration file for the GNU VPE daemon
# global options for all nodes
udp-port = 407
mtu = 1492
ifname = vpn0
# first node is named branch1 and is at 126.96.36.199
node = branch1
hostname = 188.8.131.52
# second node uses dns to resolve the address
node = branch2
hostname = www.example.net
udp-port = 500 # this host uses a different udp-port
# third node has no fixed ip address
node = branch3
connect = ondemand
The gvpe config file consists of a series of lines that contain
variable = value pairs. Empty lines are ignored. Comments start with a
# and extend to the end of the line. They can be used on their own
lines, or after any directives. Whitespace is allowed around the = sign
or after values, but not within the variable names or values
The only exception to the above is the "on" directive that can prefix
any name = value setting and will only "execute" it on the named node,
or (if the nodename starts with "!") on all nodes except the named one.
For example, set the MTU to 1450 everywhere, loglevel to noise on
branch1, and connect to ondemand everywhere but on branch2:
mtu = 1450
on branch1 loglevel = noise
on !branch2 connect = ondemand
All settings are applied "in order", that is, later settings of the
same variable overwrite earlier ones.
ANATOMY OF A CONFIG FILE
Usually, a config file starts with a few global settings (like the UDP
port to listen on), followed by node-specific sections that begin with
a node = nickname line.
Every node that is part of the network must have a section that starts
with node = nickname. The number and order of the nodes is important
and must be the same on all nodes. It is not uncommon for node sections
to be completely empty - if the default values are right.
Node-specific settings can be used at any time. If used before the
first node section they will set the default values for all following
Global settings will affect the behaviour of the running gvpe daemon,
that is, they are in some sense node-specific (config files can set
different values on different nodes using on), but will affect the
behaviour of the gvpe daemon and all connections it creates.
dns-forw-host = hostname/ip
The DNS server to forward DNS requests to for the DNS tunnel
protocol (default: 127.0.0.1, changing it is highly recommended).
dns-forw-port = port-number
The port where the dns-forw-host is to be contacted (default: 53,
which is fine in most cases).
dns-max-outstanding = integer-number-of-requests
The maximum number of outstanding DNS transport requests (default:
100). GVPE will never issue more requests then the given limit
without receiving replies. In heavily overloaded situations it
might help to set this to a low number (e.g. 3 or even 1) to limit
the number of parallel requests.
The default should be working OK for most links.
dns-overlap-factor = float
The DNS transport uses the minimum request latency (min_latency)
seen during a connection as it's timing base. This factor (default:
0.5, must be > 0) is multiplied by min_latency to get the maximum
sending rate (= minimum send interval), i.e. a factor of 1 means
that a new request might be generated every min_latency seconds,
which means on average there should only ever be one outstanding
request. A factor of 0.5 means that GVPE will send requests twice
as often as the minimum latency measured.
For congested or picky DNS forwarders you could use a value nearer
to or exceeding 1.
The default should be working OK for most links.
dns-send-interval = send-interval-in-seconds
The minimum send interval (= maximum rate) that the DNS transport
will use to send new DNS requests. GVPE will not exceed this rate
even when the latency is very low. The default is 0.01, which means
GVPE will not send more than 100 DNS requests per connection per
second. For high-bandwidth links you could go lower, e.g. to 0.001
or so. For congested or rate-limited links, you might want to go
higher, say 0.1, 0.2 or even higher.
The default should be working OK for most links.
dns-timeout-factor = float
Factor to multiply the min_latency (see dns-overlap-factor) by to
get request timeouts. The default of 8 means that the DNS transport
will resend the request when no reply has been received for longer
than eight times the minimum (= expected) latency, assuming the
request or reply has been lost.
For congested links a higher value might be necessary (e.g. 30). If
the link is very stable lower values (e.g. 2) might work nicely.
Values near or below 1 makes no sense whatsoever.
The default should be working OK for most links but will result in
low throughput if packet loss is high.
if-up = relative-or-absolute-path
Sets the path of a script that should be called immediately after
the network interface is initialized (but not necessarily up). The
following environment variables are passed to it (the values are
Variables that have the same value on all nodes:
The configuration base directory.
The network interface to initialize.
IFTYPE=native # or tincd
IFSUBTYPE=linux # or freebsd, darwin etc..
The interface type (native or tincd) and the subtype (usually
the OS name in lowercase) that this GVPE was configured for.
Can be used to select the correct syntax to use for network-
The MTU to set the interface to. You can use lower values (if
done consistently on all nodes), but this is usually either
inefficient or simply ineffective.
The number of nodes in this GVPE network.
Variables that are node-specific and with values pertaining to the
node running this GVPE:
The value of the configuration directive if-up-data.
The MAC address the network interface has to use.
Might be used to initialize interfaces on platforms where GVPE
does not do this automatically. Please see the gvpe.osdep(5)
man page for platform-specific information.
The nickname of the node.
The numerical node ID of the node running this instance of
GVPE. The first node mentioned in the config file gets ID 1,
the second ID 2 and so on.
In addition, all node-specific variables (except NODEID) will be
available with a postfix of _nodeid, which contains the value for
that node, e.g. the MAC_1 variable contains the MAC address of node
#1, while the NODENAME_22 variable contains the name of node #22.
Here is a simple if-up script:
ip link set $IFNAME up
[ $NODENAME = branch1 ] && ip addr add 10.0.0.1 dev $IFNAME
[ $NODENAME = branch2 ] && ip addr add 10.1.0.1 dev $IFNAME
ip route add 10.0.0.0/8 dev $IFNAME
More complicated examples (using routing to reduce ARP traffic) can
be found in the etc/ subdirectory of the distribution.
ifname = devname
Sets the tun interface name to the given name. The default is OS-
specific and most probably something like tun0.
ifpersist = yes|true|on | no|false|off
Should the tun/tap device be made persistent, that is, should the
device stay up even when gvpe exits? Some versions of the tunnel
device have problems sending packets when gvpe is restarted in
persistent mode, so if the connections can be established but you
cannot send packets from the local node, try to set this to off and
do an ifconfig down on the device.
ip-proto = numerical-ip-protocol
Sets the protocol number to be used for the rawip protocol. This is
a global option because all nodes must use the same protocol, and
since there are no port numbers, you cannot easily run more than
one gvpe instance using the same protocol, nor can you share the
protocol with other programs.
The default is 47 (GRE), which has a good chance of tunneling
through firewalls (but note that gvpe's rawip protocol is not GRE
compatible). Other common choices are 50 (IPSEC, ESP), 51 (IPSEC,
AH), 4 (IPIP tunnels) or 98 (ENCAP, rfc1241).
Many versions of Linux seem to have a bug that causes them to
reorder packets for some ip protocols (GRE, ESP) but not for others
(AH), so choose wisely (that is, use 51, AH).
http-proxy-host = hostname/ip
The http-proxy-* family of options are only available if gvpe was
compiled with the --enable-http-proxy option and enable tunneling
of tcp connections through a http proxy server.
http-proxy-host and http-proxy-port should specify the hostname and
port number of the proxy server. See http-proxy-loginpw if your
proxy requires authentication.
Please note that gvpe will still try to resolve all hostnames in
the configuration file, so if you are behind a proxy without access
to a DNS server better use numerical IP addresses.
To make best use of this option disable all protocols except TCP in
your config file and make sure your routers (or all other nodes)
are listening on a port that the proxy allows (443, https, is a
If you have a router, connecting to it will suffice. Otherwise TCP
must be enabled on all nodes.
http-proxy-host = proxy.example.com
http-proxy-port = 3128 # 8080 is another common choice
http-proxy-auth = schmorp:grumbeere
http-proxy-port = proxy-tcp-port
The port where your proxy server listens.
http-proxy-auth = login:password
The optional login and password used to authenticate to the proxy
server, separated by a literal colon (:). Only basic authentication
is currently supported.
keepalive = seconds
Sets the keepalive probe interval in seconds (default: 60). After
this many seconds of inactivity the daemon will start to send
keepalive probe every 3 seconds until it receives a reply from the
other end. If no reply is received within 15 seconds, the peer is
considered unreachable and the connection is closed.
loglevel = noise|trace|debug|info|notice|warn|error|critical
Set the logging level. Connection established messages are logged
at level info, notable errors are logged with error. Default is
mtu = bytes
Sets the maximum MTU that should be used on outgoing packets
(basically the MTU of the outgoing interface) The daemon will
automatically calculate maximum overhead (e.g. UDP header size,
encryption blocksize...) and pass this information to the if-up
Recommended values are 1500 (ethernet), 1492 (pppoe), 1472 (pptp).
This value must be the minimum of the MTU values of all nodes.
node = nickname
Not really a config setting but introduces a node section. The
nickname is used to select the right configuration section and must
be passed as an argument to the gvpe daemon.
node-up = relative-or-absolute-path
Sets a command (default: none) that should be called whenever a
connection is established (even on rekeying operations). Note that
node-up/down scripts will be run asynchronously, but execution is
serialised, so there will only ever be one such script running.
In addition to all the variables passed to if-up scripts, the
following environment variables will be set (values are just
The name of the remote node.
The node id of the remote node.
The "socket info" of the target node, protocol dependent but
usually in the format protocol/ip:port.
The numerical IP address of the remote node (gvpe accepts
connections from everywhere, as long as the other node can
DESTPORT=655 # deprecated
The protocol port used by the other side, if applicable.
Node-up scripts get called with STATE=up, node-change scripts
get called with STATE=change and node-down scripts get called
Here is a nontrivial example that uses nsupdate to update the name
=> ip mapping in some DNS zone:
echo update delete $DESTNODE.lowttl.example.net. a
echo update add $DESTNODE.lowttl.example.net. 1 in a $DESTIP
} | nsupdate -d -k $CONFBASE:key.example.net.
node-change = relative-or-absolute-path
Same as node-change, but gets called whenever something about a
connection changes (such as the source IP address).
node-down = relative-or-absolute-path
Same as node-up, but gets called whenever a connection is lost.
pid-file = path
The path to the pid file to check and create (default:
private-key = relative-path-to-key
Sets the path (relative to the config directory) to the private key
(default: hostkey). This is a printf format string so every % must
be doubled. A single %s is replaced by the hostname, so you could
use paths like hostkeys/%s to fetch the files at the location where
gvpectrl puts them.
Since only the private key file of the current node is used and the
private key file should be kept secret per-node to avoid spoofing,
it is not recommended to use this feature.
rekey = seconds
Sets the rekeying interval in seconds (default: 3600). Connections
are reestablished every rekey seconds, making them use a new
nfmark = integer
This advanced option, when set to a nonzero value (default: 0),
tries to set the netfilter mark (or fwmark) value on all sockets
gvpe uses to send packets.
This can be used to make gvpe use a different set of routing rules.
For example, on GNU/Linux, the if-up could set nfmark to 1000 and
then put all routing rules into table 99 and then use an ip rule to
make gvpe traffic avoid that routing table, in effect routing
normal traffic via gvpe and gvpe traffic via the normal system
ip rule add not fwmark 1000 lookup 99
NODE SPECIFIC SETTINGS
The following settings are node-specific, that is, every node can have
different settings, even within the same gvpe instance. Settings that
are set before the first node section set the defaults, settings that
are set within a node section only apply to the given node.
allow-direct = nodename
Allow direct connections to this node. See deny-direct for more
compress = yes|true|on | no|false|off
For the current node, this specified whether it will accept
compressed packets, and for all other nodes, this specifies whether
to try to compress data packets sent to this node (default: yes).
Compression is really cheap even on slow computers, has no size
overhead at all and will only be used when the other side supports
compression, so enabling this is often a good idea.
connect = ondemand | never | always | disabled
Sets the connect mode (default: always). It can be always (always
try to establish and keep a connection to the given node), never
(never initiate a connection to the given host, but accept
connections), ondemand (try to establish a connection when there
are outstanding packets in the queue and take it down after the
keepalive interval) or disabled (node is bad, don't talk to it).
Routers will automatically be forced to always unless they are
disabled, to ensure all nodes can talk to each other.
deny-direct = nodename | *
Deny direct connections to the specified node (or all nodes when *
is given). Only one node can be specified, but you can use multiple
allow-direct and deny-direct statements. This only makes sense in
networks with routers, as routers are required for indirect
Sometimes, a node cannot reach some other nodes for reasons of
network connectivity. For example, a node behind a firewall that
only allows connections to/from a single other node in the network.
In this case one should specify deny-direct = * and allow-direct =
othernodename (the other node must be a router for this to work).
The algorithm to check whether a connection may be direct is as
1. Other node mentioned in an allow-direct? If yes, allow the
2. Other node mentioned in a deny-direct? If yes, deny direct
3. Allow the connection.
That is, allow-direct takes precedence over deny-direct.
The check is done in both directions, i.e. both nodes must allow a
direct connection before one is attempted, so you only need to
specify connect limitations on one node.
dns-domain = domain-suffix
The DNS domain suffix that points to the DNS tunnel server for this
The domain must point to a NS record that points to the dns-
dns-domainname = tunnel.example.net
dns-hostname = tunnel-server.example.net
Corresponds to the following DNS entries in the example.net domain:
tunnel.example.net. NS tunnel-server.example.net.
tunnel-server.example.net. A 184.108.40.206
dns-hostname = hostname/ip
The address to bind the DNS tunnel socket to, similar to the
hostname, but for the DNS tunnel protocol only. Default: 0.0.0.0,
but that might change.
dns-port = port-number
The port to bind the DNS tunnel socket to. Must be 53 on DNS tunnel
enable-dns = yes|true|on | no|false|off
See gvpe.protocol(7) for a description of the DNS transport
protocol. Avoid this protocol if you can.
Enable the DNS tunneling protocol on this node, either as server or
as client. Support for this transport protocol is only available
when gvpe was compiled using the --enable-dns option.
enable-icmp = yes|true|on | no|false|off
See gvpe.protocol(7) for a description of the ICMP transport
Enable the ICMP transport using ICMP packets of type icmp-type on
enable-rawip = yes|true|on | no|false|off
See gvpe.protocol(7) for a description of the RAW IP transport
Enable the RAW IPv4 transport using the ip-proto protocol (default:
enable-tcp = yes|true|on | no|false|off
See gvpe.protocol(7) for a description of the TCP transport
Enable the TCPv4 transport using the tcp-port port (default: no).
Support for this transport protocol is only available when gvpe was
compiled using the --enable-tcp option.
enable-udp = yes|true|on | no|false|off
See gvpe.protocol(7) for a description of the UDP transport
Enable the UDPv4 transport using the udp-port port (default: no,
unless no other protocol is enabled for a node, in which case this
protocol is enabled automatically).
NOTE: Please specify enable-udp = yes if you want to use it even
though it might get switched on automatically, as some future
version might default to another default protocol.
hostname = hostname | ip [can not be defaulted]
Forces the address of this node to be set to the given DNS hostname
or IP address. It will be resolved before each connect request, so
dyndns should work fine. If this setting is not specified and a
router is available, then the router will be queried for the
address of this node. Otherwise, the connection attempt will fail.
Note that DNS resolving is done synchronously, pausing the daemon.
If that is an issue you need to specify IP addresses.
icmp-type = integer
Sets the type value to be used for outgoing (and incoming) packets
sent via the ICMP transport.
The default is 0 (which is echo-reply, also known as "ping-reply").
Other useful values include 8 (echo-request, a.k.a. "ping") and 11
(time-exceeded), but any 8-bit value can be used.
if-up-data = value
The value specified using this directive will be passed to the
if-up script in the environment variable IFUPDATA.
inherit-tos = yes|true|on | no|false|off
Whether to inherit the TOS settings of packets sent to the tunnel
when sending packets to this node (default: yes). If set to yes
then outgoing tunnel packets will have the same TOS setting as the
packets sent to the tunnel device, which is usually what you want.
max-retry = positive-number
The maximum interval in seconds (default: 3600, one hour) between
retries to establish a connection to this node. When a connection
cannot be established, gvpe uses exponential back-off capped at
this value. It's sometimes useful to set this to a much lower value
(e.g. 120) on connections to routers that usually are stable but
sometimes are down, to assure quick reconnections even after longer
max-ttl = seconds
Expire packets that couldn't be sent after this many seconds
(default: 60). Gvpe will normally queue packets for a node without
an active connection, in the hope of establishing a connection
soon. This value specifies the maximum lifetime a packet will stay
in the queue, if a packet gets older, it will be thrown away.
max-queue = positive-number>=1
The maximum number of packets that will be queued (default: 512)
for this node. If more packets are sent then earlier packets will
be expired. See max-ttl, above.
router-priority = 0 | 1 | positive-number>=2
Sets the router priority of the given node (default: 0, disabled).
If some node tries to connect to another node but it doesn't have a
hostname, it asks a router node for it's IP address. The router
node chosen is the one with the highest priority larger than 1 that
is currently reachable. This is called a mediated connection, as
the connection itself will still be direct, but it uses another
node to mediate between the two nodes.
The value 0 disables routing, that means if the node receives a
packet not for itself it will not forward it but instead drop it.
The special value 1 allows other hosts to route through the router
host, but they will never route through it by default (i.e. the
config file of another node needs to specify a router priority
higher than one to choose such a node for routing).
The idea behind this is that some hosts can, if required, bump the
router-priority setting to higher than 1 in their local config to
route through specific hosts. If router-priority is 0, then routing
will be refused, so 1 serves as a "enable, but do not use by
Nodes with router-priority set to 2 or higher will always be forced
to connect = always (unless they are disabled).
tcp-port = port-number
Similar to udp-port (default: 655), but sets the TCP port number.
udp-port = port-number
Sets the port number used by the UDP protocol (default: 655, not
officially assigned by IANA!).
CONFIG DIRECTORY LAYOUT
The default (or recommended) directory layout for the config directory
The config file.
The if-up script
If used the node up or node-down scripts.
The private key (taken from hostkeys/nodename) of the current host.
The public keys of the other nodes, one file per node.
gvpe(5), gvpe(8), gvpectrl(8).
Marc Lehmann <email@example.com>