Provided by:
openswan_2.4.12+dfsg-1.3_i386 
NAME
ipsec.conf - IPsec configuration and connections
DESCRIPTION
The optional ipsec.conf file specifies most configuration and control
information for the Openswan IPsec subsystem. (The major exception is
secrets for authentication; see ipsec.secrets(5).) Its contents are not
security-sensitive unless manual keying is being done for more than
just testing, in which case the encryption/authentication keys in the
descriptions for the manually-keyed connections are very sensitive (and
those connection descriptions are probably best kept in a separate
file, via the include facility described below).
The file is a text file, consisting of one or more sections. White
space followed by # followed by anything to the end of the line is a
comment and is ignored, as are empty lines which are not within a
section.
A line which contains include and a file name, separated by white
space, is replaced by the contents of that file, preceded and followed
by empty lines. If the file name is not a full pathname, it is
considered to be relative to the directory containing the including
file. Such inclusions can be nested. Only a single filename may be
supplied, and it may not contain white space, but it may include shell
wildcards (see sh(1)); for example:
include ipsec.*.conf
The intention of the include facility is mostly to permit keeping
information on connections, or sets of connections, separate from the
main configuration file. This permits such connection descriptions to
be changed, copied to the other security gateways involved, etc.,
without having to constantly extract them from the configuration file
and then insert them back into it. Note also the also and alsoflip
parameters (described below) which permit splitting a single logical
section (e.g. a connection description) into several actual sections.
The first significant line of the file must specify the version of this
specification that it conforms to:
version 2
A section begins with a line of the form:
type name
where type indicates what type of section follows, and name is an
arbitrary name which distinguishes the section from others of the same
type. (Names must start with a letter and may contain only letters,
digits, periods, underscores, and hyphens.) All subsequent non-empty
lines which begin with white space are part of the section; comments
within a section must begin with white space too. There may be only one
section of a given type with a given name.
Lines within the section are generally of the form
parameter=value
(note the mandatory preceding white space). There can be white space on
either side of the =. Parameter names follow the same syntax as section
names, and are specific to a section type. Unless otherwise explicitly
specified, no parameter name may appear more than once in a section.
An empty value stands for the system default value (if any) of the
parameter, i.e. it is roughly equivalent to omitting the parameter line
entirely. A value may contain white space only if the entire value is
enclosed in double quotes ("); a value cannot itself contain a double
quote, nor may it be continued across more than one line.
Numeric values are specified to be either an â
There is currently one parameter which is available in any type of
section:
also the value is a section name; the parameters of that section are
appended to this section, as if they had been written as part of
it. The specified section must exist, must follow the current
one, and must have the same section type. (Nesting is permitted,
and there may be more than one also in a single section,
although it is forbidden to append the same section more than
once.) This allows, for example, keeping the encryption keys for
a connection in a separate file from the rest of the
description, by using both an also parameter and an include
line. (Caution, see BUGS below for some restrictions.)
alsoflip
can be used in a conn section. It acts like an also that flips
the referenced section’s entries left-for-right.
Parameter names beginning with x- (or X-, or x_, or X_) are reserved
for user extensions and will never be assigned meanings by IPsec.
Parameters with such names must still observe the syntax rules (limits
on characters used in the name; no white space in a non-quoted value;
no newlines or double quotes within the value). All other as-yet-unused
parameter names are reserved for future IPsec improvements.
A section with name %default specifies defaults for sections of the
same type. For each parameter in it, any section of that type which
does not have a parameter of the same name gets a copy of the one from
the %default section. There may be multiple %default sections of a
given type, but only one default may be supplied for any specific
parameter name, and all %default sections of a given type must precede
all non-%default sections of that type. %default sections may not
contain also or alsoflip parameters.
Currently there are two types of section: a config section specifies
general configuration information for IPsec, while a conn section
specifies an IPsec connection.
CONN SECTIONS
A conn section contains a connection specification, defining a network
connection to be made using IPsec. The name given is arbitrary, and is
used to identify the connection to ipsec_auto(8) and ipsec_manual(8).
Here’s a simple example:
conn snt
left=10.11.11.1
leftsubnet=10.0.1.0/24
leftnexthop=172.16.55.66
leftsourceip=10.0.1.1
right=192.168.22.1
rightsubnet=10.0.2.0/24
rightnexthop=172.16.88.99
rightsourceip=10.0.2.1
keyingtries=%forever
A note on terminology... In automatic keying, there are two kinds of
communications going on: transmission of user IP packets, and
gateway-to-gateway negotiations for keying, rekeying, and general
control. The data path (a set of â
To avoid trivial editing of the configuration file to suit it to each
system involved in a connection, connection specifications are written
in terms of left and right participants, rather than in terms of local
and remote. Which participant is considered left or right is arbitrary;
IPsec figures out which one it is being run on based on internal
information. This permits using identical connection specifications on
both ends. There are cases where there is no symmetry; a good
convention is to use left for the local side and right for the remote
side (the first letters are a good mnemonic).
Many of the parameters relate to one participant or the other; only the
ones for left are listed here, but every parameter whose name begins
with left has a right counterpart, whose description is the same but
with left and right reversed.
(required)â; a parameter required for manual keying need not be included for a connection which will use only automatic keying, and vice versa.
Parameters are optional unless marked â
CONN PARAMETERS: GENERAL
The following parameters are relevant to both automatic and manual
keying. Unless otherwise noted, for a connection to work, in general it
is necessary for the two ends to agree exactly on the values of these
parameters.
type the type of the connection; currently the accepted values are
tunnel (the default) signifying a host-to-host, host-to-subnet,
or subnet-to-subnet tunnel; transport, signifying host-to-host
transport mode; passthrough, signifying that no IPsec processing
should be done at all; drop, signifying that packets should be
discarded; and reject, signifying that packets should be
discarded and a diagnostic ICMP returned.
left (required) the IP address of the left participant’s
public-network interface, in any form accepted by
ipsec_ttoaddr(3) or one of several magic values. If it is
%defaultroute, and the config setup section’s, interfaces
specification contains %defaultroute, left will be filled in
automatically with the local address of the default-route
interface (as determined at IPsec startup time); this also
overrides any value supplied for leftnexthop. (Either left or
right may be %defaultroute, but not both.) The value %any
signifies an address to be filled in (by automatic keying)
during negotiation. The value %opportunistic signifies that both
left and leftnexthop are to be filled in (by automatic keying)
from DNS data for left’s client. The values %group and
%opportunisticgroup makes this a policy group conn: one that
will be instantiated into a regular or opportunistic conn for
each CIDR block listed in the policy group file with the same
name as the conn.
leftsubnet
private subnet behind the left participant, expressed as
network/netmask (actually, any form acceptable to
ipsec_ttosubnet(3)); if omitted, essentially assumed to be
left/32, signifying that the left end of the connection goes to
the left participant only. If the global option virtual_private
has been set, the special keyword vhost:%priv can be used to
designate the allowed NAT’ed networks this option can take. If
one wants to support both the allowed virtual_private networks
as well as non-NAT’ed connection, this subnet option can be set
to rightsubnet=vhost:%priv, %no. The special value %priv will be
filled in with the network ranges specified in the global option
virtual_private=
leftprotoport
allowed protocols and ports over connection, also called Port
Selectors. The argument is in the form protocol, which can be a
number or a name that will be looked up in /etc/protocols, such
as leftprotoport=icmp, or in the form of protocol/port, such as
tcp/smtp. Ports can be defined as a number (eg. 25) or as a name
(eg smtp) which will be looked up in /etc/services. A special
keyword %any can be used to allow all ports of a certain
protocol. The most common use of this option is for L2TP
connections to only allow l2tp packets (UDP port 1701), eg:
leftprotoport=17/1701. Some clients, notably older Windows XP
and some Mac OSX clients, use a random high port as source port.
In those cases rightprotoport=17/%any can be used to allow all
UDP traffic on the connection. Note that this option is part of
the proposal, so it cannot be arbitrarily left out if one end
does not care about the traffic selection over this connection -
both peers have to agree. The Port Selectors show up in the
output of ipsec eroute and ipsec auto --status eg:"l2tp":
193.110.157.131[@aivd.xelernace.com]:7/1701...%any:17/1701 This
option only filters outbound traffic. Inbound traffic selection
must still be based on firewall rules activated by an updown
script. The variablees $PLUTO_MY_PROTOCOL, $PLUTO_PEER_PROTOCOL,
$PLUTO_MY_PORT, and $PLUTO_PEER_PORT are available for use in
updown scripts. Older workarounds for bugs involved a setting of
17/0 to denote all ports were allowed. This notation should no
longer be used.
leftnexthop
next-hop gateway IP address for the left participant’s
connection to the public network; defaults to %direct (meaning
right). If the value is to be overridden by the
left=%defaultroute method (see above), an explicit value must
not be given. If that method is not being used, but leftnexthop
is %defaultroute, and interfaces=%defaultroute is used in the
config setup section, the next-hop gateway address of the
default-route interface will be used. The magic value %direct
signifies a value to be filled in (by automatic keying) with the
peer’s address. Relevant only locally, other end need not agree
on it.
leftsourceip
the IP address for this host to use when transmitting a packet
to the other side of this link. Relevant only locally, the other
end need not agree. This option is used to make the gateway
itself use its internal IP, which is part of the leftsubnet, to
communicate to the rightsubnet or right. Otherwise, it will use
its nearest IP address, which is its public IP address. This
option is mostly used when defining subnet-subnet connections,
so that the gateways can talk to each other and the subnet at
the other end, without the need to build additional host-subnet,
subnet-host and host-host tunnels.
leftupdown
updownâ script to run to adjust routing and/or firewalling when the status of the connection changes (default ipsec _updown). May include positional parameters separated by white space (although this requires enclosing the whole string in quotes); including shell metacharacters is unwise. See ipsec_pluto(8) for details. Relevant only locally, other end need not agree on it.
what â
leftfirewall
This option is obsolete and should not used anymore.
CONN PARAMETERS: AUTOMATIC KEYING
The following parameters are relevant for automatic keying, the normal
mode of operation for IPsec. They are ignored in manual keying. Unless
otherwise noted, for a connection to work, in general it is necessary
for the two ends to agree exactly on the values of these parameters.
keyexchange
method of key exchange; the default and currently the only
accepted value is ike
auto what operation, if any, should be done automatically at IPsec
startup; currently-accepted values are add (signifying an ipsec
auto --add), route (signifying that plus an ipsec auto
--route), start (signifying that plus an ipsec auto --up),
manual (signifying an ipsec manual --up), and ignore (also the
default) (signifying no automatic startup operation). See the
config setup discussion below. Relevant only locally, other end
need not agree on it (but in general, for an
intended-to-be-permanent connection, both ends should use
auto=start to ensure that any reboot causes immediate
renegotiation). For roadwarrior connections (right=%any), it is
not known where the client will show up, so one has to use
auto=add
auth whether authentication should be done as part of ESP encryption,
or separately using the AH protocol; acceptable values are esp
(the default) and ah.
authby how the two security gateways should authenticate each other;
acceptable values are secret for shared secrets, rsasig for RSA
digital signatures (the default), secret|rsasig for either, and
never if negotiation is never to be attempted or accepted
(useful for shunt-only conns). Digital signatures are superior
in every way to shared secrets.
ike IKE encryption/authentication algorithm to be used for the
connection (phase 1 aka ISAKMP SA). The format is
"cipher-hash-modpgroup, cipher-hash-modpgroup, ..." Any left out
option will be filled in with all allowed default options.
Multiple proposals are seperated by a comma. If an ike= line is
specified, no other received proposals will be accepted.
Formerly there was a distinction (by using a "!" symbol) between
"strict mode" or not. That mode has been obsoleted. If an ike=
option is specified, the mode is always strict, meaning no other
received proposals will be accepted. Some examples are
ike=3des-sha1,aes-sha1, ike=aes, ike=aes128-md5-modp2048,
ike=3des-md5-modp1024,esp=aes-sha1-modp1536 or ike=modp1536. The
options must be suitable as a value of ipsec_spi(8)’s --ike
option. The default is to use IKE, and to allow all combinations
of:
cipher: 3des or aes
hash: sha1 or md5
pfsgroup (DHgroup): modp1024 or modp1536
If Openswan was compiled with extra INSECURE and BROKEN options,
then the des (1des) and null cipher, as well as modp768 are
available. This turns your VPN into a joke. Do not enable these
options.
esp ESP encryption/authentication algorithm to be used for the
connection (phase2 aka IPsec SA). The format is identical to the
ike option listed above. The options must be suitable as a value
of ipsec_spi(8)’s --esp option. The default is to use ESP. The
default values are the same as for ike= Note also that not all
ciphers available to the kernel (eg through CryptoAPI) are
necessarilly supported here.
ah AH authentication algorithm to be used for the connection, e.g
here. hmac-md5 The options must be suitable as a value of
ipsec_spi(8)’s --ah option. The default is not to use AH. If for
some (invalid) reason you still think you need AH, please use
esp with the null encryption cipher instead. Note also that not
all ciphers available to the kernel (eg through CryptoAPI) are
necessarilly supported here.
leftid how the left participant should be identified for
authentication; defaults to left. Can be an IP address (in any
ipsec_ttoaddr(3) syntax) or a fully-qualified domain name
preceded by @ (which is used as a literal string and not
resolved). The magic value %myid stands for the current setting
of myid.
leftrsasigkey
the left participant’s public key for RSA signature
authentication, in RFC 2537 format using ipsec_ttodata(3)
encoding. The magic value %none means the same as not specifying
a value (useful to override a default). The value %dnsondemand
(the default) means the key is to be fetched from DNS at the
time it is needed. The value %dnsonload means the key is to be
fetched from DNS at the time the connection description is read
from ipsec.conf; currently this will be treated as %none if
right=%any or right=%opportunistic. The value %dns is currently
treated as %dnsonload but will change to %dnsondemand in the
future. The identity used for the left participant must be a
specific host, not %any or another magic value. The value %cert
will load the information required from a certificate defined in
%leftcert and automatically define leftid for you. Caution: if
two connection descriptions specify different public keys for
the same leftid, confusion and madness will ensue.
leftrsasigkey2
if present, a second public key. Either key can authenticate the
signature, allowing for key rollover.
leftcert
If you are using leftrsasigkey=%cert this defines the
certificate you would like to use. It should point to a X.509
encoded certificate file. If you do not specify a full pathname,
by default it will look in /etc/ipsec.d/certs. If openswan has
been compiled with USE_SMARTCARD=true, then this option can also
be set to leftcert=%smartcard. If multiple smartcards or USB
tokens are present, they can be specified using
leftcert=%smartcard<reader nr><PKCS#15 key id>
leftsendcert
This option configures when Openswan will send X.509
certificates to the remote host. Acceptable values are
yes|always (signifying that we should always send a
certificate), ifasked (signifying that we should send a
certificate if the remote end asks for it), and no|never
(signifying that we will never send a X.509 certificate). The
default for this option is ifasked which may break compatibility
with other vendor’s IPSec implementations, such as Cisco and
SafeNet. If you find that you are getting errors about no ID/Key
found, you likely need to set this to always. This per-conn
option replaces the obsolete global nocrsend option.
leftca specifies the authorized Certificate Agency (CA) that signed the
certificate of the peer. If undefined, it defaults to the CA
that signed the certificate specified in leftcert. The special
rightca=%same is implied when not specifying a rightca and means
that only peers with certificates signed by the same CA as the
leftca will be allowed. This option is only useful in complex
multi CA certificate situations. When using a single CA, it can
be safely omitted for left and right.
leftxauthserver
Left is an XAUTH server. This can use PAM for authentication or
md5 passwords in /etc/ipsec.d/passwd. These are additional
credentials to verify the user identity, and should not be
confused with the XAUTH group secret, which is just a regular
PSK defined in ipsec.secrets. The other side of the connection
should be configured as rightxauthclient. XAUTH connections
cannot rekey, so rekey=no should be specified in this conn. For
further details on how to compile and use XAUTH, see
README.XAUTH. Acceptable values are yes or no (the default).
leftxauthclient
Left is an XAUTH client. The xauth connection will have to be
started interactively and cannot be configured using auto=start.
Instead, it has to be started from the commandline using ipsec
auto --up connname. You will then be prompted for the username
and password. To setup an XAUTH connection non-interactively,
which defeats the whole purpose of XAUTH, but is regularly
requested by users, it is possible to use a whack command -
ipsec whack --name baduser --ipsecgroup-xauth --xauthname
badusername --xauthpass password --initiate The other side of
the connection should be configured as rightxauthserver.
Acceptable values are yes or no (the default).
leftmodecfgserver
Left is a Mode Config server. It can push network configuration
to the client. Acceptable values are yes or no (the default).
leftmodecfgclient
Left is a Mode Config client. It can receive network
configuration from the server. Acceptable values are yes or no
(the default).
forceencaps
In some cases, for example when ESP packets are filtered or when
a broken IPsec peer does not properly recognise NAT, it can be
useful to force RFC-3948 encapsulation. forceencaps=yes forces
the NAT detection code to lie and tell the remote peer that
RFC-3948 encapsulation (ESP in UDP port 4500 packets) is
required. For this option to have any effect, the setup section
option nat_traversal=yes needs to be set. Acceptable values are
yes or no (the default).
dpddelay
Set the delay (in seconds) between Dead Peer Dectection (RFC
3706) keepalives (R_U_THERE, R_U_THERE_ACK) that are sent for
this connection (default 30 seconds). If dpdtimeout is set, but
not dpddelay, dpddelay will be set to the default.
dpdtimeout
Set the length of time (in seconds) we will idle without hearing
either an R_U_THERE poll from our peer, or an R_U_THERE_ACK
reply. After this period has elapsed with no response and no
traffic, we will declare the peer dead, and remove the SA
(default 120 seconds). If dpddelay is set, but not dpdtimeout,
dpdtimeout will be set to the default.
dpdaction
When a DPD enabled peer is declared dead, what action should be
taken. hold (default) means the eroute will be put into %hold
status, while clear means the eroute and SA with both be
cleared. dpdaction=clear is really only usefull on the server of
a Road Warrior config. The action restart is used on tunnels
that need to be permanently up, and have static IP addresses.
modecfgpull
Pull the Mode Config network information from the server.
Acceptable values are yes or no (the default).
pfs whether Perfect Forward Secrecy of keys is desired on the
connection’s keying channel (with PFS, penetration of the
key-exchange protocol does not compromise keys negotiated
earlier); Since there is no reason to ever refuse PFS, Openswan
will allow a connection defined with pfs=no to use PFS anyway.
Acceptable values are yes (the default) and no.
pfsgroup
PFS group to be used if pfs=yes, e.g. pfsgroup=modp1536 Because
PFS group is not negotiated it is single valued and must be
previously coordinated with peer. Possible values are: modp1024,
modp1536, modp2048, modp3072 and modp4096. If not specified, it
will use same DH group of phase1. Default value is the same
value as Phase1’s DH group.
aggrmode
Use Aggressive Mode instead of Main Mode. Aggressive Mode is
less secure, and vulnerable to Denial Of Service attacks. It is
also vulnerable to brute force attacks with software such as
ikecrack. It should not be used, and it should especially not be
used with XAUTH and group secrets (PSK). If the remote system
administrator insists on staying irresponsible, enable this
option.
Aggressive Mode is further limited to only one proposal - there
is no room for negotation. Therefor it is mandatory for
Aggressive Mode connections that both ike= and esp= options are
specified with exactly one fully specified proposal. Acceptable
values are yes or no (the default).
keylife
how long a particular instance of a connection (a set of
encryption/authentication keys for user packets) should last,
from successful negotiation to expiry; acceptable values are an
integer optionally followed by s (a time in seconds) or a
decimal number followed by m, h, or d (a time in minutes, hours,
or days respectively) (default 8h, maximum 24h). Normally, the
connection is renegotiated (via the keying channel) before it
expires. The two ends need not exactly agree on keylife,
although if they do not, there will be some clutter of
superseded connections on the end which thinks the lifetime is
longer.
rekey whether a connection should be renegotiated when it is about to
expire; acceptable values are yes (the default) and no. The two
ends need not agree, but while a value of no prevents Pluto from
requesting renegotiation, it does not prevent responding to
renegotiation requested from the other end, so no will be
largely ineffective unless both ends agree on it.
rekeymargin
how long before connection expiry or keying-channel expiry
should attempts to negotiate a replacement begin; acceptable
values as for keylife (default 9m). Relevant only locally, other
end need not agree on it.
rekeyfuzz
maximum percentage by which rekeymargin should be randomly
increased to randomize rekeying intervals (important for hosts
with many connections); acceptable values are an integer, which
may exceed 100, followed by a ‘%’ (default set by
ipsec_pluto(8), currently 100%). The value of rekeymargin, after
this random increase, must not exceed keylife. The value 0% will
suppress time randomization. Relevant only locally, other end
need not agree on it.
keyingtries
how many attempts (a whole number or %forever) should be made to
negotiate a connection, or a replacement for one, before giving
up (default %forever). The value %forever means â
ikelifetime
ISAKMP SAâ) should last before being renegotiated; acceptable values as for keylife (default set by ipsec_pluto(8), currently 1h, maximum 24h). The two-ends-disagree case is similar to that of keylife.
how long the keying channel of a connection (buzzphrase: â
compress
whether IPComp compression of content is proposed on the
connection (link-level compression does not work on encrypted
data, so to be effective, compression must be done before
encryption); acceptable values are yes and no (the default). The
two ends need not agree. A value of yes causes IPsec to propose
both compressed and uncompressed, and prefer compressed. A value
of no prevents IPsec from proposing compression; a proposal to
compress will still be accepted.
disablearrivalcheck
whether KLIPS’s normal tunnel-exit check (that a packet emerging
from a tunnel has plausible addresses in its header) should be
disabled; acceptable values are yes and no (the default).
Tunnel-exit checks improve security and do not break any normal
configuration. Relevant only locally, other end need not agree
on it.
failureshunt
what to do with packets when negotiation fails. The default is
none: no shunt; passthrough, drop, and reject have the obvious
meanings.
CONN PARAMETERS: MANUAL KEYING
The following parameters are relevant only to manual keying, and are
ignored in automatic keying. It is EXTREMELY UNLIKELY that you will
actually want to use manual keying. It is much harder to configure then
automatic keying, and inheritently insecure when used for a prolonged
time (eg production) due to the complete lack of key renewal, session
keys or perfect forward secrecy.
Unless otherwise noted, for a connection to work, in general it is
necessary for the two ends to agree exactly on the values of these
parameters. A manually-keyed connection must specify at least one of AH
or ESP.
spi (this or spibase required for manual keying) the SPI number to
be used for the connection (see ipsec_manual(8)); must be of the
form 0xhex, where hex is one or more hexadecimal digits (note,
it will generally be necessary to make spi at least 0x100 to be
acceptable to KLIPS, and use of SPIs in the range 0x100-0xfff is
recommended)
spibase
(this or spi required for manual keying) the base number for the
SPIs to be used for the connection (see ipsec_manual(8)); must
be of the form 0xhex0, where hex is one or more hexadecimal
digits (note, it will generally be necessary to make spibase at
least 0x100 for the resulting SPIs to be acceptable to KLIPS,
and use of numbers in the range 0x100-0xff0 is recommended)
espenckey
ESP encryption key (must be suitable as a value of
ipsec_spi(8)’s --enckey option) (may be specified separately for
each direction using leftespenckey (leftward SA) and
rightespenckey parameters)
espauthkey
ESP authentication key (must be suitable as a value of
ipsec_spi(8)’s --authkey option) (may be specified separately
for each direction using leftespauthkey (leftward SA) and
rightespauthkey parameters)
espreplay_window
ESP replay-window setting, an integer from 0 (the ipsec_manual
default, which turns off replay protection) to 64; relevant only
if ESP authentication is being used
leftespspi
SPI to be used for the leftward ESP SA, overriding automatic
assignment using spi or spibase; typically a hexadecimal number
beginning with 0x
ahkey (required if ah is present) AH authentication key (must be
suitable as a value of ipsec_spi(8)’s --authkey option) (may be
specified separately for each direction using leftahkey
(leftward SA) and rightahkey parameters)
ahreplay_window
AH replay-window setting, an integer from 0 (the ipsec_manual
default, which turns off replay protection) to 64
leftahspi
SPI to be used for the leftward AH SA, overriding automatic
assignment using spi or spibase; typically a hexadecimal number
beginning with 0x
CONFIG SECTIONS
At present, the only config section known to the IPsec software is the
one named setup, which contains information used when the software is
being started (see ipsec_setup(8)). Here’s an example:
config setup
interfaces="ipsec0=eth1 ipsec1=ppp0"
klipsdebug=none
plutodebug=control
nat_traversal=yes
virtual_private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%4:172.16.0.0/12
(required)â.
Parameters are optional unless marked â
The currently-accepted parameter names in a config setup section are:
myid the identity to be used for %myid. %myid is used in the implicit
policy group conns and can be used as an identity in explicit
conns. If unspecified, %myid is set to the IP address in
%defaultroute (if that is supported by a TXT record in its
reverse domain), or otherwise the system’s hostname (if that is
supported by a TXT record in its forward domain), or otherwise
it is undefined. An explicit value generally starts with ‘‘@’’.
interfaces
This option is for KLIPS and KLIPSNG (mast) only and will be
ignored when using NETKEY, Windows or BSD stacks. It specifies
the virtual and physical interfaces for IPsec to use: a single
virtual=physical pair, a (quoted!) list of pairs separated by
white space, or %none. One of the pairs may be written as
%defaultroute, which means: find the interface d that the
default route points to, and then act as if the value was
‘‘ipsec0=d’’. %defaultroute is the default; %none must be used
to denote no interfaces. If %defaultroute is used (implicitly or
explicitly) information about the default route and its
interface is noted for use by ipsec_manual(8) and
ipsec_auto(8).)
nat_traversal
whether to accept/offer to support NAT (NAPT, also known as "IP
Masqurade") workaround for IPsec. Acceptable values are: yes and
no (the default). This parameter may eventually become
per-connection.
virtual_private
contains the networks that are allowed as subnet= for the remote
client. In other words, the address ranges that may live behind
a NAT router through which a client connects. This value is
usually set to all the RFC-1918 address space, excluding the
space used in the local subnet behind the NAT (An IP address
cannot live at two places at once). IPv4 address ranges are
denoted as %v4:a.b.c.d/mm and IPv6 is denoted as
%v6:aaaa::bbbb:cccc:dddd/mm. One can exclude subnets by using
the !. For example, if the VPN server is giving access to
192.168.1.0/24, this option should be set to:
virtual_private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%4:172.16.0.0/12,%v4:!192.168.1.0/24.
This parameter is only needed on the server side and not on the
client side that resides behind the NAT router, as the client
will just use its IP address for the inner IP setting. This
parameter may eventually become per-connection.
nhelpers
how many pluto helpers are started to help with cryptographic
operations. Pluto will start (n-1) of them, where n is the
number of CPU’s you have (including hypherthreaded CPU’s). A
value of 0 forces pluto to do all operations in the main
process. A value of -1 tells pluto to perform the above
calculation. Any other value forces the number to that amount.
myid the identity to be used for %myid. %myid is used in the implicit
policy group conns and can be used as an identity in explicit
conns. If unspecified, %myid is set to the IP address in
%defaultroute (if that is supported by a TXT record in its
reverse domain), or otherwise the system’s hostname (if that is
supported by a TXT record in its forward domain), or otherwise
it is undefined. An explicit value generally starts with ‘‘@’’.
crlcheckinterval
interval, specified in seconds, after which pluto will verify
loaded X.509 CRL’s for expiration. If any of the CRL’s is
expired, or if they previously failed to get updated, a new
attempt at updating the CRL is made. The first attempt to update
a CRL is started at two times the crlcheckinterval. If set to 0,
which is also the default value if this option is not specified,
CRL updating is disabled.
strictcrlpolicy
if not set, pluto is tolerant about missing or expired X.509
Certificate Revocation Lists (CRL’s), and will allow peer
certificates as long as they do not appear on an expired CRL.
When this option is enabled, all connections with an expired or
missing CRL will be denied. Active connections will be
terminated at rekey time. This setup is more secure, but also
dangerous. If the CRL is fetched through an IPsec tunnel with a
CRL that expired, the entire VPN server will be dead in the
water until a new CRL is manually transferred to the machine (if
it allows non-IPsec connections). Acceptable values are yes or
no (the default).
forwardcontrol
whether setup should turn IP forwarding on (if it’s not already
on) as IPsec is started, and turn it off again (if it was off)
as IPsec is stopped; acceptable values are yes and (the default)
no. For this to have full effect, forwarding must be disabled
before the hardware interfaces are brought up (e.g.,
net.ipv4.ip_forward = 0 in /etc/sysctl.conf), because IPsec
doesn’t get control early enough to do that. If this option is
not specified, and subnet-subnet tunnels are configured, then IP
forwarding should be enabled by the system administrator.
rp_filter
whether and how setup should adjust the reverse path filtering
mechanism for the physical devices to be used. Values are
%unchanged (to leave it alone) or 0, 1, 2 (values to set it to).
/proc/sys/net/ipv4/conf/PHYS/rp_filter is badly documented; it
must be 0 in many cases for ipsec to function. The default value
for the parameter is 0, that is, to disable rp_filter for all
interfaces used.
facilityâ name and priority to use for startup/shutdown log messages, default daemon.error.
syslog the syslog(2) â
klipsdebug
how much KLIPS debugging output should be logged. An empty
value, or the magic value none, means no debugging output (the
default). The magic value all means full output. Otherwise only
the specified types of output (a quoted list, names separated by
white space) are enabled; for details on available debugging
types, see ipsec_klipsdebug(8). This KLIPS option has no effect
on NETKEY, Windows or BSD stacks.
plutodebug
how much Pluto debugging output should be logged. An empty
value, or the magic value none, means no debugging output (the
default). The magic value all means full output. Otherwise only
the specified types of output (a quoted list, names without the
--debug- prefix, separated by white space) are enabled; for
details on available debugging types, see ipsec_pluto(8).
plutorestartoncrash
prevent pluto from restarting after it crashed. This option
should only be used when a post-mortem of a core file is
desired. It prevents pluto from restarting and possibly
overwriting an older core file.
plutoopts
additional options to pass to pluto upon startup. See
ipsec_pluto(8).
plutostderrlog
do not use syslog, but rather log to stderr, and direct stderr
to the argument file.
dumpdir
in what directory should things started by setup (notably the
Pluto daemon) be allowed to dump core? The empty value (the
default) means they are not allowed to.
manualstart
which manually-keyed connections to set up at startup (empty, a
name, or a quoted list of names separated by white space); see
ipsec_manual(8). Default is none.
pluto whether to start Pluto or not; Values are yes (the default) or
no (useful only in special circumstances).
plutowait
should Pluto wait for each negotiation attempt that is part of
startup to finish before proceeding with the next? Values are
yes or no (the default).
prepluto
shell command to run before starting Pluto (e.g., to decrypt an
encrypted copy of the ipsec.secrets file). It’s run in a very
simple way; complexities like I/O redirection are best hidden
within a script. Any output is redirected for logging, so
running interactive commands is difficult unless they use
/dev/tty or equivalent for their interaction. Default is none.
postpluto
shell command to run after starting Pluto (e.g., to remove a
decrypted copy of the ipsec.secrets file). It’s run in a very
simple way; complexities like I/O redirection are best hidden
within a script. Any output is redirected for logging, so
running interactive commands is difficult unless they use
/dev/tty or equivalent for their interaction. Default is none.
fragicmp
whether a tunnel’s need to fragment a packet should be reported
back with an ICMP message, in an attempt to make the sender
lower his PMTU estimate; acceptable values are yes (the default)
and no. This KLIPS option has no effect on NETKEY, Windows or
BSD stacks.
hidetos
whether a tunnel packet’s TOS field should be set to 0 rather
than copied from the user packet inside; acceptable values are
yes (the default) and no. This KLIPS option has no effect on
NETKEY, Windows or BSD stacks.
uniqueids
whether a particular participant ID should be kept unique, with
any new (automatically keyed) connection using an ID from a
different IP address deemed to replace all old ones using that
ID. Acceptable values are yes (the default) and no. Participant
IDs normally are unique, so a new (automatically-keyed)
connection using the same ID is almost invariably intended to
replace an old one.
overridemtu
value that the MTU of the ipsecn interface(s) should be set to,
overriding IPsec’s (large) default. This parameter is needed
only in special situations. This KLIPS option has no effect on
NETKEY, Windows or BSD stacks.
IMPLICIT CONNS
The system automatically defines several conns to implement default
policy groups. These are used to enable the establishing of
Opportunitic Encryption IPsec tunnels. That is, setting up IPsec
tunnels with peers you have no pre-arranged configuration with.
Opportunistic Encryption is currently only supported using the KLIPS or
KLIPSNG (mast) stack, and should not be enabled when using NETKEY,
Windows or BSD stacks.
Each can be overridden by explicitly defining a new conn with the same
name. If the new conn has auto=ignore, the definition is suppressed.
Here are the automatically supplied definitions.
conn clear
type=passthrough
authby=never
left=%defaultroute
right=%group
auto=route
conn clear-or-private
type=passthrough
left=%defaultroute
leftid=%myid
right=%opportunisticgroup
failureshunt=passthrough
keyingtries=3
ikelifetime=1h
keylife=1h
rekey=no
auto=route
conn private-or-clear
type=tunnel
left=%defaultroute
leftid=%myid
right=%opportunisticgroup
failureshunt=passthrough
keyingtries=3
ikelifetime=1h
keylife=1h
rekey=no
auto=route
conn private
type=tunnel
left=%defaultroute
leftid=%myid
right=%opportunisticgroup
failureshunt=drop
keyingtries=3
ikelifetime=1h
keylife=1h
rekey=no
auto=route
conn block
type=reject
authby=never
left=%defaultroute
right=%group
auto=route
# default policy
conn packetdefault
type=tunnel
left=%defaultroute
leftid=%myid
left=0.0.0.0/0
right=%opportunistic
failureshunt=passthrough
keyingtries=3
ikelifetime=1h
keylife=1h
rekey=no
auto=route
These conns are not affected by anything in conn %default. They will
only work if %defaultroute works. The leftid will be the interfaces IP
address; this requires that reverse DNS records be set up properly.
The implicit conns are defined after all others. It is appropriate and
reasonable to use also=private-or-clear (for example) in any other
opportunistic conn.
POLICY GROUP FILES
The optional files under /etc/ipsec.d/policy, including
/etc/ipsec.d/policies/clear
/etc/ipsec.d/policies/clear-or-private
/etc/ipsec.d/policies/private-or-clear
/etc/ipsec.d/policies/private
/etc/ipsec.d/policies/block
may contain policy group configuration information to supplement
ipsec.conf. Their contents are not security-sensitive.
These files are text files. Each consists of a list of CIDR blocks, one
per line. White space followed by # followed by anything to the end of
the line is a comment and is ignored, as are empty lines.
A connection in /etc/ipsec.conf which has right=%group or
right=%opportunisticgroup is a policy group connection. When a policy
group file of the same name is loaded, with
ipsec auto --rereadgroups
or at system start, the connection is instantiated such that each CIDR
block serves as an instance’s right value. The system treats the
resulting instances as normal connections.
For example, given a suitable connection definition private, and the
file /etc/ipsec.d/policy/private with an entry 192.0.2.3, the system
creates a connection instance private#192.0.2.3. This connection
inherits all details from private, except that its right client is
192.0.2.3.
DEFAULT POLICY GROUPS
The standard Openswan install includes several policy groups which
provide a way of classifying possible peers into IPsec security
classes: private (talk encrypted only), private-or-clear (prefer
encryption), clear-or-private (respond to requests for encryption),
clear and block. Implicit policy groups apply to the local host only,
and are implemented by the IMPLICIT CONNECTIONS described above.
CHOOSING A CONNECTION
When choosing a connection to apply to an outbound packet caught with a
%trap, the system prefers the one with the most specific eroute that
includes the packet’s source and destination IP addresses. Source
subnets are examined before destination subnets. For initiating, only
routed connections are considered. For responding, unrouted but added
connections are considered.
When choosing a connection to use to respond to a negotiation which
doesn’t match an ordinary conn, an opportunistic connection may be
instantiated. Eventually, its instance will be /32 -> /32, but for
earlier stages of the negotiation, there will not be enough information
about the client subnets to complete the instantiation.
FILES
/etc/ipsec.conf
/etc/ipsec.d/policies/clear
/etc/ipsec.d/policies/clear-or-private
/etc/ipsec.d/policies/private-or-clear
/etc/ipsec.d/policies/private
/etc/ipsec.d/policies/block
SEE ALSO
ipsec(8), ipsec_ttoaddr(8), ipsec_whack(8), ipsec_auto(8),
ipsec_manual(8), ipsec_rsasigkey(8)
HISTORY
Designed for the FreeS/WAN project <http://www.freeswan.org:
http://www.freeswan.org> by Henry Spencer.
BUGS
When type or failureshunt is set to drop or reject, Openswan blocks
outbound packets using eroutes, but assumes inbound blocking is handled
updownâ script. However, the default ipsec _updown provides no help in controlling a modern firewall.
by the firewall. Openswan offers firewall hooks via an â
The use of %any with the protoport= option is ambiguous. Should the SA
permits any port through or should the SA negotiate any single port
through? The first is a basic conn with a wildcard. The second is a
template. The second is the current behaviour, and it’s wrong for quite
a number of uses involving TCP. The keyword %one may be introduced in
the future to seperate these two cases.
Including attributes of the keying channel (authentication methods,
ikelifetime, etc.) as an attribute of a connection, rather than of a
participant pair, is dubious and incurs limitations.
Ipsec_manual is not nearly as generous about the syntax of subnets,
addresses, etc. as the usual Openswan user interfaces. Four-component
dotted-decimal must be used for all addresses. It is smart enough to
translate bit-count netmasks to dotted-decimal form.
It would be good to have a line-continuation syntax, especially for the
very long lines involved in RSA signature keys.
The ability to specify different identities, authby, and public keys
for different automatic-keyed connections between the same participants
is misleading; this doesn’t work dependably because the identity of the
participants is not known early enough. This is especially awkward for
the â
In principle it might be necessary to control MTU on an
interface-by-interface basis, rather than with the single global
override that overridemtu provides.
A number of features which could be implemented in both manual and
automatic keying actually are not yet implemented for manual keying.
This is unlikely to be fixed any time soon.
If conns are to be added before DNS is available, left=FQDN,
leftnextop=FQDN, and leftrsasigkey=%dnsonload will fail. ipsec_pluto(8)
does not actually use the public key for our side of a conn but it
isn’t generally known at a add-time which side is ours (Road Warrior
and Opportunistic conns are currently exceptions).
The myid option does not affect explicit ipsec auto --add or ipsec
auto --replace commands for implicit conns.
IPSEC.CONF(5)