Provided by: libreswan_3.23-4_amd64 
NAME
ipsec.conf - IPsec configuration and connections
DESCRIPTION
The ipsec.conf file specifies most configuration and control information for the Libreswan IPsec
subsystem. (The major exception is secrets for authentication; see ipsec.secrets(5).) Its contents are
not security-sensitive. Configurations can be added using this configuration file or by using ipsec whack
directly. This means that technically, the ipsec.conf file is optional, but a few warning might show up
when this file is missing.
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 /etc/ipsec.d/*.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 may specify a version of this specification for backwards
compatibility with freeswan and openswan. It is ignored and unused. For compatibility with openswan,
specify:
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 “integer” (a sequence of digits) or a “decimal number”
(sequence of digits optionally followed by `.' and another sequence of digits).
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. %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) 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 “IPsec SAs”) used for user packets is herein referred to as the
“connection”; the path used for negotiations (built with “ISAKMP SAs”) is referred to as the “keying
channel”.
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.
Parameters are optional unless marked “(required)”
CONN PARAMETERS: GENERAL
The following parameters are relevant to IKE automatic 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
connaddrfamily
the connection address family of the connection; currently the accepted values are ipv4 (the
default); or ipv6. This option is confusing, especially when doing IPv4-in-IPv6 or IPv6-in-IPv4
tunnels. The developers hope to remove this option in the near future for proper auto-detection. For
now, set connaddrfamily= to the family of the *subnet= options, and if those are not defined, to the
family of the left=/right= options.
IPv6 is supported with NETKEY and with KLIPS in all Libreswan versions
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). Currently, IPv4 and IPv6 IP addresses are supported. There are 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 value can also contain the interface name, which will then later be used to obtain the IP
address from to fill in. For example %ppp0 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.
If using IP addresses in combination with NAT, always use the actual local machine's (NATed) IP
address, and if the remote (eg right=) is NATed as well, the remote's public (not NATed) IP address.
Note that this makes the configuration no longer symmetrical on both sides, so you cannot use an
identical configuration file on both hosts.
leftsubnet
private subnet behind the left participant, expressed as network/netmask (actually, any form
acceptable to ipsec_ttosubnet(3)); Currently, IPv4 and IPv6 ranges are supported. if omitted,
essentially assumed to be left/32, signifying that the left end of the connection goes to the left
participant only
It supports two magic shorthands vhost: and vnet:, which can list subnets in the same syntax as
virtual-private. The value %priv expands to the networks specified in virtual-private. The value %no
means no subnet. A common use for allowing roadwarriors to come in on public IPs or via accepted
NATed networks from RFC1918 is to use leftsubnet=vhost:%no,%priv. The vnet: option can be used to
allow RFC1918 subnets without hardcoding them. When using vnet the connection will instantiate,
allowing for multiple tunnels with different subnets.
leftsubnets
specify multiple private subnets behind the left participant, expressed as { networkA/netmaskA
networkB/netmaskB [...] } If both a leftsubnets= and rightsubnets= are defined, all combinations of
subnet tunnels will be established as IPsec tunnels. You cannot use leftsubnet= and leftsubnets=
together. For examples see testing/pluto/multinet-*.
leftvti
the address/mask to configure on the VTI interface when vti-interface is set. It takes the form of
network/netmask (actually, any form acceptable to ipsec_ttosubnet(3)); Currently, IPv4 and IPv6
ranges are supported. This option is often used in combination with routed based VPNs.
leftaddresspool
address pool from with the IKEv1 XAUTH or IKEv2 server can assign IP addresses to clients. When
configured as a server, using leftxauthserver=yes this option specifies the address pool from which
IP addresses are taken to assign the clients. The syntax of the address pool specifies a range (not a
CIDR), in the following syntax: rightaddresspool=192.168.1.100-192.168.1.200. Generally, the
rightaddresspool= option will be accompanied by rightxauthclient=yes, leftxauthserver=yes and
leftsubnet=0.0.0.0/0 option.
When leftaddresspool= is specified, the connection may not specify either leftsubnet= or
leftsubnets=. Address pools are fully allocated when the connection is loaded, so the ranges should
be sane. For example, specifying a range rightaddresspool=10.0.0.0-11.0.0.0 will lead to massive
memory allocation. Address pools specifying the exact same range are shared between different
connections. Different addresspools should not be defined to partially overlap.
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.
To filter on specific icmp type and code, use the higher 8 bits for type and the lower 8 bits for
port. For example, to allow icmp echo packets (type 8, code 0) the 'port' would be 0x0800, or 2048 in
decimal, so you configure leftprotoport=icmp/2048. Similarly, to allow ipv6-icmp Neighbour Discovery
which has type 136 (0x88) and code 0(0x00) this becomes 0x8800 or in decimal 34816 resulting in
leftprotoport=ipv6-icmp/34816 .
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.libreswan.org]: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
variables $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
any single UDP port (not UDP port 0). Some clients, most notably OSX, uses a random high port,
instead of port 1701 for L2TP.
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. Both IPv4 and IPv6 addresses are supported.
leftupdown
what "updown" 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. An
example to enable routing when using the NETKEY stack, one can use:
leftupdown="ipsec _updown --route yes"
To disable calling an updown script, set it to the empty string, eg leftupdown="" or
leftupdown="%disabled".
See ipsec_pluto(8) for details. Relevant only locally, other end need not agree on it.
leftfirewall
This option is obsolete and should not used anymore.
If one or both security gateways are doing forwarding firewalling (possibly including masquerading), and
this is specified using the firewall parameters, tunnels established with IPsec are exempted from it so
that packets can flow unchanged through the tunnels. (This means that all subnets connected in this
manner must have distinct, non-overlapping subnet address blocks.) This is done by the default updown
script (see ipsec_pluto(8)).
The implementation of this makes certain assumptions about firewall setup, and the availability of the
Linux Advanced Routing tools. In situations calling for more control, it may be preferable for the user
to supply his own updown script, which makes the appropriate adjustments for his system.
CONN PARAMETERS: AUTOMATIC KEYING
The following parameters are relevant to automatic keying via IKE. 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.
auto
what operation, if any, should be done automatically at IPsec startup; currently-accepted values are
add (signifying an ipsec auto --add), ondemand (signifying that plus an ipsec auto --ondemand), start
(signifying that plus an ipsec auto --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).
The option ondemand used to be called route
authby
how the two security gateways should authenticate each other; acceptable values are rsasig (the
default) for RSA digital signatures based authentication, secret for shared secrets (PSK)
authentication, secret|rsasig for either, never if negotiation is never to be attempted or accepted
(useful for shunt-only conns), and null for null-authentication.
If asymmetric authentication is requested, IKEv2 must be enabled, and the options leftauth= and
rightauth= should be used instead of authby.
Digital signatures are superior in every way to shared secrets. Especially IKEv1 in Aggressive Mode
is vulnerable to offline dictionary attacks and is performed routinely by at least the NSA on
monitored internet traffic globally. The never option is only used for connections that do not
actually start an IKE negotiation, such as type=passthrough connections. The auth method null is used
for "anonymous opportunistic IPsec" and should not be used for regular pre-configured IPsec VPNs.
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 separated 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=aes_ctr, ike=aes_gcm256-sha2,
ike=aes128-md5;modp2048, ike=aes256-sha2;dh19, ike=aes128-sha1;dh22,
ike=3des-md5;modp1024,aes-sha1;modp1536. The options must be suitable as a value of ipsec_spi(8)'s
--ike option. The default IKE proposal depends on the version of libreswan used. It follow the
recommendations of RFC4306, RFC7321 and as of this writing their successor draft documents RFC4306bis
and RFC7321bis. For IKEv1, SHA1 and MODP1536 are still allowed per default for backwards
compatibility, but 3DES and MODP1024 are not allowed per default. IKEv2's minimum is AES, MODP2048
and SHA2. The default key size is 256 bits. The default AES_GCM ICV is 16 bytes.
Note that AES-GCM is an AEAD algorithm, meaning that it performs encryption+authentication in one
step. This means that AES-GCM must not specify an authentication algorithm. However, it does require
a PRF function, so the second argument to an AEAD algorithm denotes the PRF. So ike=aes_gcm-sha2
means propose AES_GCM with no authentication and using SHA2 as the prf. Note that for phase2alg,
there is no prf, so AES-GCM is specified for ESP as phase2alg=aes_gcm-null. The AES-GCM and AES-CCM
algorithms support 8,12 and 16 byte ICV's. These can be specified using a postfix, for example
aes_gcm_a (for 8), aes_gcm_b (for 12) and aes_gcm_c (for 16). The default (aes_gcm without postfix)
refers to the 16 byte ICV version. It is strongly recommended to NOT use the 8 or 12 byte versions of
GCM or CCM.
Weak algorithms are regularly removed from libreswan. Currently, 1DES and modp768 have been removed
and modp1024 will be removed in the near future. Additionally, md5 and sha1 will be removed within
the next few years. Null encryption is available, and should only be used for testing or benchmarking
purposes. Please do not request for insecure algorithms to be re-added to libreswan.
Diffie-Hellman groups 19,20 and 21 from RFC- 5903 and 22, 23 and 24 from RFC-5114 are also supported.
For all groups, the "dh" keyword can be used. For the MODP based groups, the modp= keyword can be
used. for example ike=3des-sha1;dh19. The RFC-5114 DH groups are extremely controversial and MUST NOT
be used unless forced (administratively) by the other party. Support for these groups will most
likely be removed in 2017, as it cannot be proven these DH groups do not have a cryptographic
trapdoor embedded in them (a backdoor by the USG who provided these primes without revealing the
seeds and generation process used). Due the the weakness od DH22, support for this group is not
compiled in by default and can be re-enabled using USE_DH22=true.
The modp syntax will be removed in favour of the dh syntax in the future
phase2
Sets the type of SA that will be produced. Valid options are: esp for encryption (the default), ah
for authentication only.
The very first IPsec designs called for use of AH plus ESP to offer authentication, integrity and
confidentiality. That dual protocol use was a significant burden, so ESP was extended to offer all
three services, and AH remained as an auth/integ. The old mode of ah+esp is no longer supported in
compliance with RFC 8221 Section 4. Additionally, AH does not play well with NATs, so it is strongly
recommended to use ESP with the null cipher if you require unencrypted authenticated transport.
phase2alg
Specifies the algorithms that will be offered/accepted for a phase2 negotiation. If not specified, a
secure set of defaults will be used. Sets are separated using comma's.
The default values are the same as for ike= Note also that not all ciphers available to the kernel
(eg through CryptoAPI) are necessarily supported here.
The format for ESP is ENC-AUTH followed by one optional PFSgroup. For instance, "3des-md5" or
"aes256-sha1;modp2048" or "aes-sha1,aes-md5". When specifying multiple algorithms, specify the
PFSgroup last, e.g. "3des-md5,aes256-sha1;modp2048".
For RFC-5114 DH groups, use the "dh" keyword, eg "aes256-sha1;dh23". These specific DH groups are
extremely controversial and MUST NOT be used unless forced (administratively) by the other party.
Support for these groups will most likely be removed in 2017, as it cannot be proven these DH groups
do not have a cryptographic trapdoor embedded in them (a backdoor by the USG who gave us these primes
without revealing the seeds and generation process)
The format for AH is AUTH followed by an optional PFSgroup. For instance, "md5" or "sha1;modp1536".
AEAD algorithms such as AES-GCM and AES-CCM require null for the authentication algorithm, for
example phase2alg=aes_ccm-null or phase2alg=aes_gcm-null. Note that the ike= syntax for aes_gcm does
not specify a null authentication but specifies the prf instead. The supported key sizes are 128, 192
and 256, which are specified similarly to plain aes, i.e. phase2alg=aes_gcm256. A subscript of _c,
_b or _a can be used to refer to the different ICV variants where a means 8 bytes, b means 12 bytes
and c means 16 bytes. The default when not using a subscript is the 16 byte ICV, the recommended
value by RFC-4106. Therefor phase2alg=aes_gcm256-null is equivalent to phase2alg=aes_gcm_c256-null.
It is recommended to migrate to the _c versions (without specifying _c), as support for smaller ICV's
might be removed in the near future.
The supported algorithms depend on the libreswan version, OS and kernel stack used. Possible ciphers
are aes, 3des, aes_ctr, aes_gcm, aes_ccm, camellia, serpent and twofish.
Note that openswan and versions of libreswan up to 3.6 require manually adding the salt size to the
key size. Therefor, to configure an older version of openswan or libreswan, use:
"phase2alg=aes_ccm_c-280-null" to interop with a new libreswan using "phase2alg=aes_ccm256". For CCM,
the 'keysize' needs to be increased by 24, resulted in valid keysizes of 152, 215 and 280. For GCM
the 'keysize' needs to be increased by 32, resulting valid 'keysizes' of 160, 224 and 288.
sha2-truncbug
The default ESP hash truncation for sha2_256 is 128 bits. Some IPsec implementations (Linux before
2.6.33, some Cisco (2811?) routers) implement the draft version which stated 96 bits. If a draft
implementation communicates with an RFC implementation, both ends will reject encrypted packets from
each other.
This option enables using the draft 96 bits version to interop with those implementations. Currently
the accepted values are no, (the default) signifying default RFC truncation of 128 bits, or yes,
signifying the draft 96 bits truncation.
Another workaround is to switch from sha2_256 to sha2_128 or sha2_512.
ppk
EXPERIMENTAL: Post-quantum preshared keys (PPKs) to be used. Currently the accepted values are
propose or yes (the default), signifying we propose to use PPK for this connection; insist,
signifying we allow communication only if PPK is used for key derivation; never or no, signifying
that PPK should not be used for key derivation; (currently based on draft-fluhrer-qr-ikev2, not
raft-ietf-ipsecme-qr-ikev2-00)
nat-ikev1-method
NAT Traversal in IKEv1 is negotiated via Vendor ID options as specified in RFC 3947. However, many
implementations only support the draft version of the RFC. Libreswan sends both the RFC and the most
common draft versions (02, 02_n and 03) to maximize interoperability. Unfortunately, there are known
broken implementations of RFC 3947, notably Cisco routers that have not been updated to the latest
firmware. As the NAT-T payload is sent in the very first packet of the initiator, there is no method
to auto-detect this problem and initiate a workaround.
This option allows fine tuning which of the NAT-T payloads to consider for sending and processing.
Currently the accepted values are drafts, rfc, both (the default) and none. To interoperate with
known broken devices, use nat-ikev1-method=drafts. To prevent the other end from triggering IKEv1
NAT-T encapsulation, set this to none. This will omit the NAT-T payloads used to determine NAT,
forcing the other end not to use encapsulation.
esp
This option is obsolete. Please use phase2alg instead.
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 necessarily
supported here.
fragmentation
Whether or not to allow IKE fragmentation. Valid values are are yes, (the default), no or force.
IKEv1 fragmentation capabilities are negotiated via a well-known private vendor id. IKEv2
fragmentation support is implemented using RFC 7383. If pluto does not receive the fragmentation
payload, no IKE fragments will be sent, regardless of the fragmentation= setting. When set to yes,
IKE fragmentation will be attempted on the first re-transmit of an IKE packet of a size larger then
576 bytes for IPv4 and 1280 bytes for IPv6. If fragmentation is set to force, IKE fragmentation is
used on initial transmits of such sized packets as well. When we have received IKE fragments for a
connection, pluto behaves as if in force mode.
ikepad
Whether or not to pad IKEv1 messages to a multiple of 4 bytes. Valid values are are yes, (the
default) and no.
IKE padding is allowed in IKEv1 but it is known to cause interoperability issues. The ikepad= option
can be used to disable IKEv1 padding. This is required for some devices (such as Checkpoint in
Aggressive Mode) that reject padded IKEv1 packets. In IKEv2, no padding is allowed, and this option
has no effect. If you find a device that seems to require IKE padding in IKEv2, please contact the
libreswan developers. This option should almost never be enabled.
ikev2
IKEv2 (RFC 7296) settings to be used. Currently the accepted values are permit, (the default)
signifying no IKEv2 should be transmitted, but will be accepted if the other ends initiates to us
with IKEv2; never or no signifying no IKEv2 negotiation should be transmitted or accepted; propose or
yes signifying that we permit IKEv2, and also use it as the default to initiate; insist, signifying
we only accept and receive IKEv2 - IKEv1 negotiations will be rejected.
If the ikev2= setting is set to permit or propose, Libreswan will try and detect a "bid down" attack
from IKEv2 to IKEv1. Since there is no standard for transmitting the IKEv2 capability with IKEv1,
Libreswan uses a special Vendor ID "CAN-IKEv2". If a fall back from IKEv2 to IKEv1 was detected, and
the IKEv1 negotiation contains Vendor ID "CAN-IKEv2", Libreswan will immediately attempt and IKEv2
rekey and refuse to use the IKEv1 connection. With an ikev2= setting of insist, no IKEv1 negotiation
is allowed, and no bid down attack is possible.
mobike
Whether to allow MOBIKE (RFC 4555) to enable a connection to migrate its endpoint without needing to
restart the connection from scratch. This is used on mobile devices that switch between wired,
wireless or mobile data connections. Current values are no (the default) or yes, Only connection
acting as modecfgclient will allow the initiator to migrate using mobike. Only connections acting as
modecfgserver will allow clients to migrate.
VTI and MOBIKE might not work well when used together.
esn
Whether or not to enable Extended Sequence Number (ESN) for the IPsec SA. ESN is typically used for
very high-speed links (10Gbps or faster) where the standard 32 bit sequence number is exhausted too
quickly, causing IPsec SA's rekeys to happen too often. Accepted values are no (the default), yes and
either. If either is specified as an initiator, the responder will make the choice. As a responder,
if either is received, no is picked.
decap-dscp
Enable decapsulating the Differentiated Services Code Point (DSCP, formerly known as Terms Of Service
(TOS)) bits. If these bits are set on the inner (encrypted) IP packets, these bits are set on the
decrypted IP packets. Acceptable values are no (the default) or yes. Currently this feature is only
implemented for the Linux XFRM/NETKEY stack.
nopmtudisc
Disable Path MTU discovery for the IPsec SA. Acceptable values are no (the default) or yes. Currently
this feature is only implemented for the Linux XFRM/NETKEY stack.
narrowing
IKEv2 (RFC5996) Section 2.9 Traffic Selector narrowing options. Currently the accepted values are no,
(the default) signifying no narrowing will be proposed or accepted, or yes, signifying IKEv2
negotiation may allow establishing an IPsec connection with narrowed down traffic selectors. This
option is ignored for IKEv1.
There are security implications in allowing narrowing down the proposal. For one, what should be done
with packets that we hoped to tunnel, but cannot. Should these be dropped or send in the clear?
Second, this could cause thousands of narrowed down Child SAs to be created if the conn has a broad
policy (eg 0/0 to 0/0). One possible good use case scenario is that a remote end (that you fully
trust) allows you to define a 0/0 to them, while adjusting what traffic you route via them, and what
traffic remains outside the tunnel. However, it is always preferred to setup the exact tunnel policy
you want, as this will be much clearer to the user.
sareftrack
Set the method of tracking reply packets with SArefs when using an SAref compatible stack. Currently
only the mast stack supports this. Acceptable values are yes (the default), no or conntrack. This
option is ignored when SArefs are not supported. This option is passed as PLUTO_SAREF_TRACKING to the
updown script which makes the actual decisions whether to perform any iptables/ip_conntrack
manipulation. A value of yes means that an IPSEC mangle table will be created. This table will be
used to match reply packets. A value of conntrack means that additionally, subsequent packets using
this connection will be marked as well, reducing the lookups needed to find the proper SAref by using
the ip_conntrack state. A value of no means no IPSEC mangle table is created, and SAref tracking is
left to a third-party (kernel) module. In case of a third party module, the SArefs can be relayed
using the statsbin= notification helper.
nic-offload
Set the method of Network Interface Controller (NIC) hardware offload for ESP/AH packet processing.
Acceptable values are auto (the default), yes or no. This option is separate from any CPU hardware
offload available and is currently only available on Linux 4.13+ using the NETKEY/XFRM IPsec stack,
when compiled with the options CONFIG_XFRM_OFFLOAD, CONFIG_INET_ESP_OFFLOAD and
CONFIG_INET6_ESP_OFFLOAD. The auto option will attempt to auto-detect the presence of kernel and
hardware support, and then automatically mark the IPsec SA for hardware offloading. One vendor
supporting this offload method is Mellanox.
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 which will be resolved. If
preceded by @, the value is used as a literal string and will not be resolved. To support opaque
identifiers (usually of type ID_KEY_ID, such as used by Cisco to specify Group Name, use square
brackets, eg rightid=@[GroupName]. The magic value %fromcert causes the ID to be set to a DN taken
from a certificate that is loaded. Prior to 2.5.16, this was the default if a certificate was
specified. The magic value %none sets the ID to no ID. This is included for completeness, as the ID
may have been set in the default conn, and one wishes for it to default instead of being explicitly
set. The magic value %myid stands for the current setting of myid. This is set in config setup or by
ipsec_whack(8)), or, if not set, it is the IP address in %defaultroute (if that is supported by a TXT
record in its reverse domain), or otherwise it is the system's hostname (if that is supported by a
TXT record in its forward domain), or otherwise it is undefined.
When using certificate based ID's, one need to specify the full RDN, optionally using wildcard
matching (eg CN='*'). If the RDN contains a comma, this can be masked using a comma (eg OU='Foo,, Bar
and associates')
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 nickname of your certificate in the
NSS database. This can be on software or hardware security device.
leftckaid
The hex CKAID of the X.509 certificate. Certificates are stored in the NSS database.
leftauth
How the security gateways will authenticate to the other side in the case of asymmetric
authentication; acceptable values are rsasig for RSA digital signatures based authentication, secret
for shared secrets (PSK) authentication and null for null-authentication. There is no default value -
if unset, the symmetrical authby= keyword is used to determine the authentication policy of the
connection.
If asymmetric authentication is requested, IKEv1 must be disabled. If symmetric authentication is
required, use authby= instead of leftauth/rightauth. If leftauth is set, rightauth must also be set
and authby= must not be set. Asymmetric authentication cannot use secret (psk) on one side and null
on the other side - use psk on both ends instead.
Be aware that the symmetric keyword is authby= but the asymmetric keyword is leftauth and rightauth
(without the "by").
leftca
specifies the authorized Certificate Authority (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 both left and right.
leftsendcert
This option configures when Libreswan will send X.509 certificates to the remote host. Acceptable
values are yes|always (signifying that we should always send a certificate), sendifasked (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 sendifasked 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.
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).
leftusername
The username associated with this connection. The username can be the IKEv2 XAUTH username, a GSSAPI
username or IKEv2 CP username. For the XAUTH username, the XAUTH password can be configured in the
ipsec.secrets file. This option was previously called leftxauthusername.
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).
xauthby
When IKEv1 XAUTH support is available, set the method used by XAUTH to authenticate the user with
IKEv1. The currently supported values are file (the default), pam or alwaysok. The password file is
located at /etc/ipsec.d/passwd, and follows a syntax similar to the Apache htpasswd file, except an
additional connection name argument (and optional static IP address) are also present:
username:password:conname:ipaddress
For supported password hashing methods, see crypt(3). If pluto is running in FIPS mode, some hash
methods, such as MD5, might not be available. Threads are used to launch an xauth authentication
helper for file as well as PAM methods.
The alwaysok should only be used if the XAUTH user authentication is not really used, but is required
for interoperability, as it defeats the whole point of XAUTH which is to rely on a secret only known
by a human. See also pam-authorize=yes
xauthfail
When XAUTH support is available, set the failure method desired when authentication has failed. The
currently supported values are hard (the default) and soft. A soft failure means the IPsec SA is
allowed to be established, as if authentication had passed successfully, but the XAUTH_FAILED
environment variable will be set to 1 for the updown script, which can then be used to redirect the
user into a walled garden, for example a payment portal.
pam-authorize
IKEv1 supports PAM authorization via XAUTH using xauthby=pam. IKEv2 does not support receiveing a
plaintext username and password. Libreswan does not yet support EAP authentication methods for IKE.
The pam-authorize=yes option performs an authorization call via PAM, but only includes the remote ID
(not username or password). This allows for backends to disallow an ID based on non-password
situations, such as "user disabled" or "user over quota". See also xauthby=pam
modecfgpull
Pull the Mode Config network information from the server. Acceptable values are yes or no (the
default).
modecfgdns, modecfgdomains, modecfgbanner
When configured as IKEv1 ModeCFG or IKEv2 server, specifying any of these options will cause those
options and values to be sent to the connecting client. Libreswan as a client will use these received
options to either update /etc/resolv.conf or the running unbound DNS server. When the connection is
brought down, the previous DNS resolving state is restored.
The modecfgdns option takes a comma or space separated list of IP addresses that can be used for DNS
resolution. The modecfgdomains option takes a comma or space separated list of internal domain names
that are reachable via the supplied modecfgdns DNS servers.
The IKEv1 split tunnel directive will be sent automatically if the xauth server side has configured a
network other than 0.0.0.0/0. For IKEv2, this is automated via narrowing.
remote-peer-type
Set the remote peer type. This can enable additional processing during the IKE negotiation.
Acceptable values are cisco or ietf (the default). When set to cisco, support for Cisco IPsec gateway
redirection and Cisco obtained DNS and domainname are enabled. This includes automatically updating
(and restoring) /etc/resolv.conf. These options require that XAUTH is also enabled on this
connection.
nm-configured
Mark this connection as controlled by Network Manager. Acceptable values are yes or no (the default).
Currently, setting this to yes will cause libreswan to skip reconfiguring resolv.conf when used with
XAUTH and ModeConfig.
encapsulation
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. In other cases, where IKE
is NAT'ed but ESP packets can or should flow without encapsulation, it can be useful to ignore the
NAT-Traversal auto-detection. encapsulation=yes forces the NAT detection code to lie and tell the
remote peer that RFC-3948 encapsulation (ESP in port 4500 packets) is required. encapsulation=no
ignores the NAT detection causing ESP packets to send send without encapsulation. The default value
of encapsulation=auto follows the regular outcome of the NAT auto-detection code performed in IKE.
This option replaced the obsoleted forceencaps option.
nat-keepalive
whether to send any NAT-T keep-alives. These one byte packets are send to prevent the NAT router from
closing its port when there is not enough traffic on the IPsec connection. Acceptable values are: yes
(the default) and no.
initial-contact
whether to send an INITIAL_CONTACT payload to the peer we are initiating to, if we currently have no
IPsec SAs up with that peer. Acceptable values are: no (the default) and yes. It is recommended to
leave this option unset, unless the remote peer requires it to allow reconnects. The only known peer
at this time is Cisco, which will not allow a reconnect (despite authentication) to replace an
existing IPsec SA unless it receives an INITIAL_CONTACT payload. Receiving this payload is ignored
and the choice to replace or add an IPsec SA when libreswan is a responder is purely based on the
uniqueids setting, which should be left enabled unless libreswan acts as an XAUTH server using PSK
("group secret"). This option can cause a few seconds of downtime on the IPsec tunnel between the
time the remote clears the old IPsec SA in response to our INITIAL_CONTACT message, and the time we
finish setting up the new IPsec SA. If there is an XAUTH step in between, and especially when XAUTH
requires the use of some two-factor token, this downtime could be even longer.
cisco-unity
whether to send a CISCO_UNITY payload to the peer. Acceptable values are: no (the default) and yes.
It is recommended to leave this option unset, unless the remote peer (Cisco client or server)
requires it. This option does not modify local behaviour. It can be needed to connect as a client to
a Cisco server. It can also be needed to act as a server for a Cisco client, which otherwise might
send back an error DEL_REASON_NON_UNITY_PEER.
fake-strongswan
whether to send a STRONGSWAN Vendor ID payload to the peer. Acceptable values are: no (the default)
and yes. Strongswan rejects certain proposals with private use numbers such as esp=twofish or
esp=serpent unless it receives a strongswan vendorid by the peer. This option sends such an
(unversioned) vendor id.
send-vendorid
whether to send our Vendor ID during IKE. Acceptable values are: no (the default) and yes. The vendor
id sent can be configured using the "config setup" option myvendorid=. It defaults to
OE-Libreswan-VERSION.
Vendor ID's can be useful in tracking interoperability problems. However, specific vendor
identification and software versions can be useful to an attacker when there are known
vulnerabilities to a specific vendor/version.
The prefix OE stands for "Opportunistic Encryption". This prefix was historically used by The
FreeS/WAN Project and The Openswan Project (openswan up to version 2.6.38) and in one Xeleranized
openswan versions (2.6.39). Further Xeleranized openswan's use the prefix OSW.
overlapip
a boolean (yes/no) that determines, when *subnet=vhost: is used, if the virtual IP claimed by this
states created from this connection can with states created from other connections.
Note that connection instances created by the Opportunistic Encryption or PKIX (x.509) instantiation
system are distinct internally. They will inherit this policy bit.
The default is no.
This feature is only available with kernel drivers that support SAs to overlapping conns. At present
only the (klips) mast protocol stack supports this feature.
reqid
a unique identifier used to match IPsec SAs using iptables with NETKEY/XFRM. This identifier is
normally automatically allocated in groups of 4. It is exported to the _updown script as REQID. On
Linux, reqids are supported with IP Connection Tracking and NAT (iptables). Automatically generated
values use the range 16380 and higher. Manually specified reqid values therefor must be between 1 and
16379.
Automatically generated reqids use a range of 0-3 (eg 16380-16383 for the first reqid). These are
used depending on the exact policy (AH, AH+ESP, IPCOMP, etc).
WARNING: Manually assigned reqids are all identical. Instantiations of connections (those using %any
wildcards) will all use the same reqid. If you use manual assigning you should make sure your
connections only match single road warrior only or you break multiple road warriors behind same NAT
router because this feature requires unique reqids to work.
For KLIPS, when using the MAST variant, a different mechanism called SAref is in use. See overlapip
and sareftrack.
dpddelay
Set the delay (in time units, defaults to seconds) between Dead Peer Detection (IKEv1 RFC 3706) or
IKEv2 Liveness keepalives that are sent for this connection (default 0 seconds). Set to enable
checking. If dpddelay is set, dpdtimeout also needs to be set.
dpdtimeout
Set the length of time (in time units, defaults to seconds) that we will idle without hearing back
from our peer. After this period has elapsed with no response and no traffic, we will declare the
peer dead, and remove the SA (default 0 seconds). Set value bigger than dpddelay to enable. If
dpdtimeout is set, dpddelay also needs to be set.
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.
restart means that ALL SAs to the dead peer will renegotiated.
dpdaction=clear is really only useful on the server of a Road Warrior config.
The value restart_by_peer has been obsoleted and its functionality moved into the regular restart
action.
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, Libreswan will allow a connection defined with pfs=no to use PFS
anyway. Acceptable values are yes (the default) and no.
pfsgroup
This option is obsoleted, please use phase2alg if you need the PFS to be different from phase1 (the
default) using: phase2alg=aes128-md5;modp1024
aggressive
Use IKEv1 Aggressive Mode instead of IKEv1 Main Mode. This option has no effect when IKEv2 is used.
Acceptable values are no (the default) or yes. When this option is enabled, IKEv1 Main Mode will no
longer be allowed for this connection. The old name of this option was aggrmode.
Aggressive Mode is less secure, and more 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 proposals with one DH group as there is no room to
negotiate the DH group. Therefor it is mandatory for Aggressive Mode connections that both ike= and
phase2alg= options are specified with only one fully specified proposal using one DH group.
The KE payload is created in the first exchange packet when using aggressive mode. The KE payload
depends on the DH group used. This is why there cannot be multiple DH groups in IKEv1 aggressive
mode. In IKEv2, which uses a similar method to IKEv1 Aggressive Mode, there is an INVALID_KE response
payload that can inform the initiator of the responder's desired DH group and so an IKEv2 connection
can actually recover from picking the wrong DH group by restarting its negotiation.
salifetime
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
salifetime, although if they do not, there will be some clutter of superseded connections on the end
which thinks the lifetime is longer.
The keywords "keylife" and "lifetime" are obsoleted aliases for "salifetime." Change your configs to
use "salifetime" instead.
replay-window
The size of the IPsec SA replay window protection. The default is kernel stack specific, but usually
32. Linux NETKEY/XFRM allows at least up to 2048. A value of of 0 disables replay protection.
Disabling of replay protection is sometimes used on a pair of IPsec servers in a High Availability
setup, or on servers with very unpredictable latency, such as mobile networks, which can cause an
excessive amount of out of order packets. Sequence errors can be seen in /proc/net/xfrm_stat. Note
that technically, at least the Linux kernel can install IPsec SA's with an IPsec SA Sequence Number,
but this is currently not supported by libreswan.
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 salifetime (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 salifetime. 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 “never give up”
(obsolete: this can be written 0). Relevant only locally, other end need not agree on it.
ikelifetime
how long the keying channel of a connection (buzzphrase: “ISAKMP SA”) should last before being
renegotiated; acceptable values as for salifetime (default set by ipsec_pluto(8), currently 1h,
maximum 24h). The two-ends-disagree case is similar to that of salifetime.
retransmit-timeout
how long a single packet, including retransmits of that packet, may take before the IKE attempt is
aborted. If rekeying is enabled, a new IKE attempt is started. The default set by ipsec_pluto(8),
currently is 60s. See also: retransmit-interval, rekey and keyingtries.
retransmit-interval
the initial interval time period, specified in msecs, that pluto waits before retransmitting an IKE
packet. This interval is doubled for each attempt (exponential back-off). The default set by
ipsec_pluto(8), currently is 500. See also: retransmit-timeout, rekey and keyingtries.
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).
As of libreswan 3.1, both ends must agree. In previous versions of libreswan, openswan and freeswan,
compression was always accepted even if not configured. In light of the BEAST attacks on TLS, using
compression and encryptions has come under more scrutiny, and it was decided that it should be
possible for the local policy of an endpoint to disallow compression. A value of yes causes pluto to
propose compression and reject proposals without it. A value of no prevents pluto from proposing
compression; a proposal to compress will be rejected.
metric
Set the metric for the routes to the ipsecX or mastX interface. This makes it possible to do host
failover from another interface to ipsec using route management. This value is passed to the _updown
scripts as PLUTO_METRIC. This option is only available with KLIPS or MAST on Linux. Acceptable values
are positive numbers, with the default being 1.
mtu
Set the MTU for the route(s) to the remote endpoint and/or subnets. This is sometimes required when
the overhead of the IPsec encapsulation would cause the packet the become too big for a router on the
path. Since IPsec cannot trust any unauthenticated ICMP messages, PATH MTU discovery does not work.
This can also be needed when using "6to4" IPV6 deployments, which adds another header on the packet
size. Acceptable values are positive numbers. There is no default.
tfc
Enable Traffic Flow Confidentiality ("TFC") (RFC-4303) for outgoing ESP packets in Tunnel Mode. When
enabled, ESP packets are padded to the specified size (up to the PMTU size) to prevent leaking
information based on ESP packet size. This option is ignored for AH and for ESP in Transport Mode as
those always leak traffic characteristics and applying TFC will not do anything. Acceptable values
are positive numbers. The value 0 means TFC padding is not performed. Currently this feature is only
implemented for the Linux XFRM/NETKEY stack. In IKEv2, when the notify payload
ESP_TFC_PADDING_NOT_SUPPORTED is received, TFC padding is disabled. The default is not to do any TFC
padding, but this might change in the near future.
send-no-esp-tfc
Whether or not to tell the remote peer that we do not support Traffic Flow Confidentiality ("TFC")
(RFC-4303). Possible values are no (the default) which allows the peer to use TFC or yes which
prevents to peer from using TFC. This does not affect whether this endpoint uses TFC, which only
depends on the local tfc setting. This option is only valid for IKEv2.
nflog
If set, the NFLOG group number to log this connection's pre-crypt and post-decrypt traffic to. The
default value of 0 means no logging at all. This option is only available on linux kernel 2.6.14 and
later. It allows common network utilities such as tcpdump, wireshark and dumpcap, to use nflog:XXX
pseudo interfaces where XXX is the nflog group number. During the updown phase of a connection,
iptables will be used to add and remove the source/destination pair to the nflog group specified. The
rules are setup with the nflog-prefix matching the connection name. See also the global nflog-all
option.
mark
If set, the MARK to set for the IPsec SA of this connection. The format of a CONNMARK is mark/mask.
If the mask is left out, a default mask of 0xffffffff is used. A mark value of -1 means to assign a
new global unique mark number for each instance of the connection. Global marks start at 1001. This
option is only available on linux NETKEY/XFRM kernels. It can be used with iptables to create custom
iptables rules using CONNMARK. It can also be used with Virtual Tunnel Interfaces ("VTI") to direct
marked traffic to specific vtiXX devices.
mark-in
The same as mark, but mark-in only applies to the inbound half of the IPsec SA. It overrides any
mark= setting.
mark-out
The same as mark, but mark-out only applies to the outbound half of the IPsec SA. It overrides any
mark= setting.
vti-interface
This option is used to create "Routing based VPNs" (as opposed to "Policy based VPNs"). It will
create a new interface that can be used to route traffic in for encryption/decryption. The Virtual
Tunnel Interface ("VTI") interface name is used to for all IPsec SA's created by this connection.
This requires that the connection also enables either the mark= or mark-in= / mark-out- option(s).
All traffic marked with the proper MARKs will be automatically encrypted if there is an IPsec SA
policy covering the source/destination traffic. Tools such as tcpdump and iptables can be used on all
cleartext pre-encrypt and post-decrypt traffic on the device. See the libreswan wiki for example
configurations that use VTI.
VTI interfaces are currently only supported on Linux with XFRM/NETKEY. The _updown script handles
certain Linux specific interfaces settings required for proper functioning (disable_policy,
rp_filter, forwarding, etc). Interface names are limited to 16 characters and may not allow all
characters to be used. If marking and vti-routing=yes is used, no manual iptables should be required.
However, administrators can use the iptables mangle table to mark traffic manually if desired.
vti-routing
Whether or not to add network rules or routes for IPsec SA's to the respective VTI devices. Valid
values are yes (the default) or no. When using "routing based VPNs" with a subnets policy of
0.0.0.0/0, this setting needs to set to no to prevent imploding the tunnel, and the administrator is
expected to manually add ip rules and ip routes to configure what traffic must be encrypted. When set
to yes, the _updown script will automatically route the leftsubnet/rightsubnet traffic into the VTI
device specified with vti-interface
vti-shared
Whether or not the VTI device is shared amongst connections. Valid values are no (the default) or
yes. When set to no, the VTI device is automatically deleted if the connection is a single
non-instantiated connection. If a connection instantiates (eg right=%any) then this option has no
effect, as the VTI device is not removed as it is shared with multiple roadwarriors.
priority
The priority in the kernel SPD/SAD database, when matching up packets. Each kernel (NETKEY, KLIPS,
OSX, etc) has its own mechanism for setting the priority. Setting this option to non-zero passes the
priority to the kernel stack unmodified. The maximum value depends on the stack. It is recommended
not to exceed 65536
KLIPS and NETKEY use a priority system based on "most specific match first". It uses an internal
algorithm to calculate these based on network prefix length, protocol and port selectors. A lower
value means a higher priority.
Typical values are about the 2000 range. These can be seen on the NETKEY stack using ip xfrm policy
when the connection is up. For "anonymous IPsec" or Opportunistic Encryption based connections, a
much lower priority (65535) is used to ensure administrator configured IPsec always takes precedence
over opportunistic IPsec.
sendca
How much of our available X.509 trust chain to send with the End certificate, excluding any root
CA's. Specifying issuer sends just the issuing intermediate CA, while
all will send the entire chain of intermediate CA's.none (the default) will not send any CA certs.
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.
labeled-ipsec
Whether labeled IPsec should be enabled or not; acceptable values are no (the default) and yes. See
also policy-label= and secctx-attr-type=
policy-label
The string representation of an access control security label that is interpreted by the LSM (e.g.
SELinux) for use with Labeled IPsec. See also labeled-ipsec= and secctx-attr-type=. For example,
policy-label=system_u:object_r:ipsec_spd_t:s0-s15:c0.c1023
failureshunt
what to do with packets when negotiation fails. The default is none: no shunt; passthrough, drop, and
reject have the obvious meanings.
negotiationshunt
What to do with packets during the IKE negotiation. Valid options are hold (the default) or
passthrough. This should almost always be left to the default hold value to avoid cleartext packet
leaking. The only reason to set this to passthrough is if plaintext service availability is more
important than service security or privacy, a scenario that also implies failureshunt=passthrough and
most likely authby=%null using Opportunistic Encryption.
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
protostack=auto
Parameters are optional unless marked “(required)”.
The currently-accepted parameter names in a config setup section are:
protostack
decide which protocol stack is going to be used. Valid values are "klips", "netkey" (the default) and
"mast". The "mast" stack is a variation for the KLIPS stack. The value "auto" has been obsoleted.
interfaces
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, or when
using the NETKEY stack. If %defaultroute is used (implicitly or explicitly) information about the
default route and its interface is noted for use by ipsec_auto(8).)
listen
IP address to listen on (default depends on interfaces= setting). Currently only accepts one IP
address.
ike-socket-bufsize
Set the IKE socket buffer size. Default size is determined by the OS (as of writing, this seems to be
set to 212992. On Linux this is visible via /proc/sys/net/core/rmem_default and
/proc/sys/net/core/wmem_default. On Linux, this option uses SO_RCVBUFFORCE and SO_SNDBUFFORCE so that
it can override rmem_max/wmem_max values of the OS. This requires CAP_NET_ADMIN (which is also
required for other tasks). This option can also be toggled on a running system using ipsec whack
--ike-socket-bufsize bufsize.
ike-socket-errqueue
Whether to enable or disable receiving socket errors via IP_RECVERR. The default is enabled. This
will cause the socket to receive, process and log socket errors, such as ICMP unreachable messages or
Connection Refused messages. Disabling this only makes sense on very busy servers, and even then it
might not make much of a difference. This option can also be toggled on a running system using ipsec
whack --ike-socket-errqueue-toggle.
ikeport
The IKE port to listen on. The default value is 500. As IKE is an internet standard, changing this
means pluto will no longer be able to interop with other devices, unless they have also been
explicitly configured to use a non-standard IKE port. There might also be other subtle assumptions
within the kernel that port 500 is used. Changing this port is strongly discouraged, and should
probably only be done for testing or when required to circumvent VPN blocking technologies as
employed by certain commercial companies and national governments. See also nat-ikeport.
nflog-all
If set, the NFLOG group number to log all pre-crypt and post-decrypt traffic to. The default value of
0 means no logging at all. This option is only available on linux kernel 2.6.14 and later. It allows
common network utilities such as tcpdump, wireshark and dumpcap, to use nflog:XXX pseudo interfaces
where XXX is the nflog group number. During startup and shutdown of the IPsec service, iptables
commands will be used to add or remove the global NFLOG table rules. The rules are setup with the
nflog-prefix all-ipsec. See also the per-connection nflog option.
nat_traversal
OBSOLETE. Support for NAT Traversal is always enabled.
disable_port_floating
OBSOLETE
force_keepalive
This option has been obsoleted since libreswan version 3.2. See the nat-keepalive option.
nat-ikeport
The IKE NAT Traversal floating port (see RFC-3947) to listen on. The default value is 4500. As
IKE/NATT is an internet standard, changing this means pluto will no longer be able to interoperate
with other devices, unless they have also been explicitly configured to use a non-standard IKE/NATT
port. There might also be other subtle assumptions within the kernel that port 4500 is used. Changing
this port is strongly discouraged, and should probably only be done for testing or when required to
circumvent VPN blocking technologies as employed by certain commercial companies and national
governments. See also ikeport.
keep-alive
The delay (in seconds) for NAT-T keep-alive packets, if these are enabled using nat-keepalive This
parameter may eventually become per-connection.
virtual-private
contains the networks that are allowed as subnet= for the remote clients when using the vhost: or
vnet: keywords in the subnet= parameters. 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:eeee/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,%v4:172.16.0.0/12,%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. See also leftsubnet=
Note: It seems that T-Mobile in the US and Rogers/Fido in Canada have started using 25.0.0.0/8 as
their pre-NAT range. This range technically belongs to the Defence Interoperable Network Services
Authority (DINSA), an agency of the Ministry of Defence of the United Kingdom. The network range
seems to not have been announced for decades, which is probably why these organisations "borrowed"
this range. To support roadwarriors on these 3G networks, you might have to add it to the
virtual-private= line.
myvendorid
The string to use as our vendor id (VID) when send-vendorid=yes. The default is OE-Libreswan-VERSION.
oe
This option is ignored for now. It used to determine if Opportunistic Encryption will be enabled.
Opportunistic Encryption is the term to describe using IPsec tunnels without prearrangement. It uses
IPSECKEY or TXT records to announce public RSA keys for certain IP's or identities. However, this
feature is going to be moved outside of the pluto IKE daemon into a separate process, more closely
tied with a local DNS(SEC) server. The default value used to be no, so this should not affect anyone.
Contact the developers if you are interested in working on the re-implementation of OE.
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.
seedbits
Pluto uses the NSS crypto library as its random source. Some government Three Letter Agencies require
that pluto reads additional bits from /dev/random and feed these into the NSS RNG before drawing
random from the NSS library, despite the NSS library itself already seeding its internal state. This
process can block pluto for an extended time during startup, depending on the entropy of the system.
Therefor, the default is to not perform this redundant seeding. If specifying a value, it is
recommended to specify at least 460 bits (for FIPS) or 440 bits (for BSI).
secctx-attr-type
The value for the IPsec SA security context attribute identifier which is used for Labeled IPsec.
Defaults to the private use IANA value 32001 from the IPsec SA attributes registry. Old openswan
versions might still be using the (stolen) value 10, which has since been assigned by IANA for
something else. Other values are not recommended unless IANA assigns an actual value for this. See
also labeled-ipsec= and policy-label=
plutofork
This option has been obsoleted. The pluto daemon always forks unless it is started with the --nofork
option.
crlcheckinterval
interval expressed in second units, for example crlcheckinterval=8h for 8 hours, after which pluto
will fetch new Certificate Revocation List (CRL) from crl distribution points. List of used CRL
distribution points are collected from CA certificates and end certificates. Loaded X.509 CRL's are
verified to be valid and updates are imported to NSS database. If set to 0, which is also the default
value if this option is not specified, CRL updating is disabled.
crl-strict
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 vulnerable to downtime if the CRL expires.
Acceptable values are yes or no (the default). This option used to be called strictcrlpolicy.
curl-iface
The name of the interface that is used for CURL lookups. This is needed on rare situations where the
interface needs to be forced to be different from the default interface used based on the routing
table.
curl-timeout
The timeout for the curl library calls used to fetch CRL and OCSP requests. The default is 5s.
ocsp-enable
Whether to perform Online Certificate Store Protocol ("OCSP") checks on those certificates that have
an OCSP URI defined. Acceptable values are yes or no (the default).
ocsp-strict
if set to no, pluto is tolerant about failing to obtain an OCSP responses and a certificate is not
rejected when the OCSP request fails, only when the OCSP request succeeds and lists the certificate
as revoked. If set to yes, any failure on obtaining an OCSP status for a certificate will be fatal
and the certificate will be rejected. Acceptable values are yes or no (the default).
The strict mode refers to the NSS ocspMode_FailureIsVerificationFailure mode, while non-strict mode
refers to the NSS ocspMode_FailureIsNotAVerificationFailure mode.
ocsp-method
The HTTP methods used for fetching OCSP data. Valid options are get (the default) and post. Note that
this behaviour depends on the NSS crypto library that is actually performing the fetching. When set
to the get method, post is attempted only as fallback in case of failure. When set to post, only the
post method is ever used.
ocsp-timeout
The time until an OCSP request is aborted and considered failed. The default value is 2 seconds.
ocsp-uri
The URI to use for OCSP requests instead of the default OCSP URI listed in the CA certificate. This
requires the ocsp-trustname option to be set to the nick (friendly name) of the OCSP server
certificate, which needs to be present in the NSS database. These option combined with the next
option sets the OCSP default responder.
ocsp-trustname
The nickname of the certificate that has been imported into the NSS database of the server handling
the OCSP requests. This requires the ocsp-uri option to be set as well. This option and the previous
options sets the OCSP default responder.
ocsp-cache-size
The maximum size (in number of certificates) of OCSP responses that will be kept in the cache. The
default is 1000. Setting this value to 0 means the cache is disabled.
ocsp-cache-min-age
The minimum age (in seconds) before a new fetch will be attempted. The default is 1 hour.
ocsp-cache-max-age
The maximum age (in seconds) before a new fetch will be attempted. The default is 1 day.
forwardcontrol
This option is obsolete and ignored. Please use net.ipv4.ip_forward = 0 in /etc/sysctl.conf instead
to control the ip forwarding behaviour.
rp_filter
This option is obsolete and ignored. Please use the net.ipv4.conf/[iface]/rp_filter = 0 options in
/etc/sysctl.conf instead. This option is badly documented; it must be 0 in many cases for ipsec to
function.
syslog
the syslog(2) “facility” name and priority to use for startup/shutdown log messages, default
daemon.error.
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).
uniqueids
Whether IDs should be considered identifying remote parties uniquely. Acceptable values are yes (the
default) and no. Participant IDs normally are unique, so a new connection instance using the same
remote ID is almost invariably intended to replace an old existing connection.
When the connection is defined to be a server (using xauthserver=) and the connection policy is
authby=secret, this option is ignored (as of 3.20) and old connections will never be replaced. This
situation is commonly known as clients using a "Group ID".
This option may disappear in the near future. People using identical X.509 certificates on multiple
devices are urged to upgrade to use separate certificates per client and device.
logfile
do not use syslog, but rather log to stderr, and direct stderr to the argument file. This option used
to be called plutostderrlog=
logappend
If pluto is instructed to log to a file using logfile=, this option determines whether the log file
should be appended to or overwritten. Valid options are yes (the default) to append and no to
overwrite. Since on modern systems, pluto is restarted by other daemons, such as systemd, this option
should be left at its default yes value to preserve the log entries of previous runs of pluto. The
option is mainly of use for running the test suite, which needs to create new log files from scratch.
logip
If pluto is instructed to log the IP address of incoming connections. Valid options are yes (the
default) and no. Note that this only affects regular logging. Any enabled debugging via plutodebug=
will still contain IP addresses of peers. This option is mostly meant for servers that want to avoid
logging IP addresses of incoming clients. Other identifiable information might still be logged, such
as ID payloads and X.509 certificate details. Most deployments will not want to change this from the
default.
logtime
When pluto is directed to log to a file using logfile=, this option determines whether or not to log
the current timestamp as prefix. Values are yes (the default) or no. The no value can be used to
create logs without ephemeral timestamps, such as those created when running the test suite. This
option used to be called plutostderrlogtime=
force-busy
This option has been obsoleted, please see ddos-mode.
ddos-mode
The startup mode of the DDOS defense mechanism. Acceptable values are busy, unlimited or auto (the
default). This option can also be given to the IKE daemon while running, for example by issuing ipsec
whack --ddos--busy. When in busy mode, pluto activates anti-DDoS counter measures. Currently, counter
measures consist of requiring IKEv2 anti-DDoS cookies on new incoming IKE requests, and a more
aggressive cleanup of partially established or AUTH_NULL connections.
ddos-ike-threshold
The number of half-open IKE SAs before the pluto IKE daemon will be placed in busy mode. When in busy
mode, pluto activates anti-DDoS counter measures. The default is 25000. See also ddos-mode and ipsec
whack --ddos-XXX.
max-halfopen-ike
The number of half-open IKE SAs before the IKE daemon starts refusing all new IKE attempts.
Established IKE peers are not affected. The default value is 50000.
shuntlifetime
The time until bare shunts (kernel policies not associated with connections) are deleted from the
kernel. The default value is 15m. When using Opportunistic Encryption to a specific host fails, the
system will either install a %pass or %hold shunt to let the traffic out clear text or block it.
During the the shuntlifetime, no new Opportunistic Encryption attempt will be started, although the
system will still respond to incoming OE requests from the remote IP. See also failureshunt and
negotiationshunt
xfrmlifetime
The time in seconds until the NETKEY/XFRM acquire state times out. The default value is 300 seconds.
For auto=ondemand connections and Opportunistic connections an IPsec policy is installed in the
kernel. If an incoming or outgoing packet matches this policy, a state is created in the kernel and
the kernel sends an ACQUIRE message to the IKE daemon pluto. While this state is in place, no new
acquires will come in for this connection. The default should be fine for most people. One use case
of shortening these is if opportunistc encryption is used towards cloud instances that can quickly
re-use IP addresses. This value is only used during the libreswan startup process by the ipsec
_stackmanager helper. See also failureshunt and negotiationshunt
dumpdir
in what directory should things started by setup (notably the Pluto daemon) be allowed to dump core?
The default value is /var/run/pluto. When SELinux runs in enforced mode, changing this requires a
similar change in the SELinux policy for the pluto daemon.
statsbin
This option specifies an optional external program to report tunnel state changes too. The default is
not to report tunnel state changes. This program can be used to notify the user's desktop (dbus,
NetworkManager) or to report tunnel changes to a central logging server.
ipsecdir
Specifies a directory for administrator-controlled configuration files and directories. The default
value is /etc/ipsec.d. It may contain the following files and directories:
passwd
(optional) for XAUTH support if not using PAM (this file should not be world-readable). See
README.XAUTH for more information.
nsspassword
(optional) passwords needed to unlock the NSS database in /var/lib/ipsec/nss (this file should
not be world-readable). See README.nss for more information.
policies/
a directory containing policy group configuration information. See POLICY GROUP FILES in this
document for more information.
cacerts/
DEPRECATED: a directory to store trust anchors (root certificate authority certificates). The
preferred (and default) approach is to store CA certs in the NSS database instead. See README.nss
for more information.
crls/
DEPRECATED: a directory to store certificate revocation lists. The preferred (and default)
approach is to store CRLs in the NSS database instead. See README.nss for more information.
When SELinux runs in enforced mode, changing this requires a similar change in the SELinux policy for
the pluto daemon.
On debian systems, the NSS database itself is not controlled by this value, and is instead located in
/var/lib/ipsec/nss.
secretsfile
in which file the secret credentials such as preshared keys (PSKs) are stored. See man ipsec.secrets
for the syntax. The default value is /etc/ipsec.secrets.
perpeerlog
if pluto should split the logs in a per-peer directory. Valid options are no(the default) and yes.
When enabled, logging is split into directories based on IP address. When disabled, logging is done
via syslog or a single log file, as defined by logfile=
perpeerlogdir
in what directory the per-peer log should be created, if enabled via the perpeerlog option. This will
result in sub directories in the structure /192/0/2. The default value is /var/log/pluto/peer/. When
SELinux runs in enforced mode, changing this requires a similar change in the SELinux policy for the
pluto daemon.
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 no (the default) and yes.
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.
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.
seccomp
Set the seccomp kernel syscall whitelisting feature. When set to enabled, if pluto calls a syscall
that is not on the compiled-in whitelist, the kernel will assume an exploit is attempting to use
pluto for malicious access to the system and terminate the pluto daemon. When set to tolerant, the
kernel will only block the rogue syscall and pluto will attempt to continue. If set to disabled,
pluto is allowed to call any syscall offered by the kernel, although it might be restricted via other
security mechanisms, such as capabilities, SElinux, AppArmor or other OS security features.
The current default is disabled, but it is expected that in the future this feature will be enabled
on all supported operating systems. Similarly, it is expected that further privilege separation will
reduce the allowed syscalls - for example for the crypto helpers or DNS helpers.
Warning: The restrictions of pluto are inherited by the updown scripts, so these scripts are also not
allowed to use syscalls that are forbidden for pluto.
This feature can be tested using ipsec whack --seccomp-crashtest. Warning: With seccomp=enabled,
pluto will be terminated by the kernel. With seccomp=tolerant or seccomp=disabled, pluto will report
the results of the seccomp test. SECCOMP will log the forbidden syscall numbers to the audit log, but
only with seccomp=enabled. The tool scmp_sys_resolver from the libseccomp development package can be
used to translate the syscall number into a name. See programs/pluto/pluto_seccomp.c for the list of
allowed syscalls.
IMPLICIT CONNS
The system automatically defines several conns to implement default policy groups. 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
salifetime=1h
rekey=no
auto=route
conn private-or-clear
type=tunnel
left=%defaultroute
leftid=%myid
right=%opportunisticgroup
failureshunt=passthrough
keyingtries=3
ikelifetime=1h
salifetime=1h
rekey=no
auto=route
conn private
type=tunnel
left=%defaultroute
leftid=%myid
right=%opportunisticgroup
failureshunt=drop
keyingtries=3
ikelifetime=1h
salifetime=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
salifetime=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/policies, 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 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/policies/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 Libreswan 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.
OBSOLETE
Various options have recently been obsoleted and are ignored. The options prepluto= and plutopost= have
been obsoleted because these were used by the (obsoleted) shell wrappers launching the pluto daemon. If
this functionality is needed, look at your initsystem for support. For example, the systemd initsystem
has the options ExecStartPre= and ExecStopPost= to accomplish the same. The option plutoopts= has also
been obsoleted for this reason. A replacement can be found in the PLUTO_OPTS environment variable in the
file /etc/sysconfig/pluto (Fedora/RHEL) or /etc/defaults/pluto (Debian/Ubuntu). The last two options
obsoleted by the removal of the old shell scripts are pluto= and plutowait=.
The following ipsec commands have been obsoleted: ipsec _confread, ipsec _include, ipsec _plutoload,
ipsec _realsetup, ipsec _startklips and ipsec _startnetkey due to the new parsing and startup methods and
ipsec copyright, ipsec lwdnsq, ipsec mailkey, ipsec policy, ipsec showdefaults and ipsec showpolicy
because they were no longer needed or current.
CHOOSING A CONNECTION [THIS SECTION IS EXTREMELY OUT OF DATE
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_auto(8), ipsec_rsasigkey(8)
HISTORY
Designed for the FreeS/WAN project <http://www.freeswan.org> by Henry Spencer.
BUGS
Before reporting new bugs, please ensure you are using the latest version of Libreswan, and if not using
KLIPS, please ensure you are using the latest kernel code for your IPsec stack.
When type or failureshunt is set to drop or reject, Libreswan blocks outbound packets using eroutes, but
assumes inbound blocking is handled by the firewall. Libreswan offers firewall hooks via an “updown”
script. However, the default ipsec _updown provides no help in controlling a modern firewall.
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.
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 separate these two cases.
It would be good to have a line-continuation syntax, especially for the very long lines involved in RSA
signature keys.
First packet caching is only implemented for the KLIPS(NG) and MAST stacks. NETKEY returns POSIX-breaking
responses, visible as connect: Resource temporarily unavailable errors. This affects Opportunistic
Encryption and DPD. Functionality on the BSD and Windows stacks is unknown.
Some state information is only available when using KLIPS, and will return errors on other IPsec stacks.
These include ipsec eroute, ipsec spi and ipsec look.
Multiple L2TP clients behind the same NAT router, and multiple L2TP clients behind different NAT routers
using the same Virtual IP is currently only working for the KLIPSNG stack.
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 “Road Warrior”
case, where the remote IP address is specified as 0.0.0.0, and that is considered to be the “participant”
for such connections.
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. This feature is planned for a future release.
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.
AUTHOR
Paul Wouters
documenter
libreswan 02/15/2018 IPSEC.CONF(5)