Provided by: libreswan_4.14-1ubuntu2_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 warnings might show up when this
file is missing.
ipsec.conf 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 that are not within a section.
A line that 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 that contains 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 distinct 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 that
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 that 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 that 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 that 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
hostaddrfamily
the address family of the hosts; currently the accepted values are ipv4 and ipv6. The
default is to detect this based on the IP addresses specified or the IP addresses
resolved, so this option is not needed, unless you specify hostnames that resolve to
both IPv4 and IPv6. This option used to be named connaddrfamily but its use was broken
so it was obsoleted in favour or using the new hostaddrfamily and clientaddrfamily.
clientaddrfamily
the address family of the clients (subnets); currently the accepted values are ipv4
and ipv6. The default is to detect this based on the network IP addresses specified or
the network IP addresses resolved, so this option is not needed, unless you specify
names that resolve to both IPv4 and IPv6.
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 or DNS hostname of the left participant's public-network
interface, Currently, IPv4 and IPv6 IP addresses are supported. If a DNS hostname is
used, it will be resolved to an IP address on load time, and whenever a connection is
rekeying or restarting (such as when restarted via a DPD failure detection). This
allows one to use a DNS hostname when the endpoint is on a dynamic IP address.
There are several magic values. If it is %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-*. Be aware that when using spaces as separator, that the
entire option value needs to be in double quotes.
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 where the IKEv1 ModeCFG 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) for IPv4 and CIDR for IPv6, in the
following syntax: rightaddresspool=192.168.1.100-192.168.1.200 or
rightaddresspool=2001:db8:0:3:1::/97 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, 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 XFRM 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.
leftcat
Whether to perform Client Address Translation ("CAT") when using Opportunistic IPsec
behind NAT. Accepted values are no (the default) and yes. This option should only be
enabled on the special Opportunistic IPsec connections, usually called "private" and
"private-or-clear". When set, this option causes the given addresspool IP from the
remote peer to be NATed with iptables. It will also install an additional IPsec SA
policy to cover the pre-NAT IP. See the Opportunistic IPsec information on the
libreswan website for more information and examples.
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),
and keep (signifying an add plus an attempt to keep the connection up once the remote
peer brought it up). 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; the default value is
rsasig,ecdsa which allows ECDSA with SHA-2 and RSA with SHA2 or SHA1. To limit this
further, there are the options of ecdsa for ECDSA digital signatures using SHA-2,
rsa-sha2 for RSASSA-PSS digital signatures based authentication with SHA2-256,
rsa-sha2_384 for RSASSA-PSS digital signatures based authentication with SHA2-384,
rsa-sha2_512 for RSASSA-PSS digital signatures based authentication with SHA2-512,
rsa-sha1 for RSA-PKCSv1.5 digital signatures based authentication with SHA1, 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.
For IKEv1, SHA2 based signatures are not defined and ECDSA is not implemented, so the
default authby= value is rsa-sha1. Using authby=rsasig results in only rsa-sha1 as
well. For IKEv2, using authby=rsasig means using rsa-sha2_512, rsa-sha2_384,
rsa-sha2_256 and rsa-sha1, where rsa-sha1 will used only if RFC 7427 is not supported
by the peer.
As per RFC 8221, authby=rsa-sha1 is only supported in the old style, meaning
RSA-PKCSv1.5. The SHA2 variants are only supported for the new style of RFC 7427, so
authby=rsa-sha2 will use the new style. The default authby= will remove rsa-sha1 in
the near future. It is strongly recommended that if certificates are used, the
certificates and the authby= signature methods used are the same, as it increases
interoperability and keeps the authentication of everything within one digital
signature system.
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 or IKE SA). If this option is not set, the builtin defaults will be used.
This is the preferred method, and allows for gradual automatic updates using the same
configuration. Some distributions, such as Fedora and RHEL/CentOS, use a System Wide
Crypto Policy that sets the default ike= (and esp=) lines. Specifying your own ike=
line means overriding all these system or software recommended defaults, but can be
necessary at times. Note that libreswan does not support using a PRF algorithm that is
different from the INTEGRITY (hash) algorithm by design.
The format is "cipher-hash;modpgroup, cipher-hash;modpgroup, ..." Any omitited option
will be filled in with all allowed default values. Multiple proposals are separated by
a comma. If an ike= line is specified, no other received proposals will be accepted
than those specified on the IKE line. 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.
IKEv2 allows combining elements into a single proposal. These can be specified by
using the + symbol. An example is:
ike=aes_gcm+chacha20_poly1305;dh14+dh19,aes+3des-sha2+sha1;dh14. Note that AEAD
algorithms (aes_gcm, aes_ccm, chacha20_poly1305) and non-AEAD algorithms (aes, 3des)
cannot be combined into a single proposal. To support aes and aes_gcm, two proposals
separated by a comma must be used.
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. As for libreswan 3.32, SHA1 and MODP1536(dh5) are
still allowed per default for backwards compatibility, but 3DES and MODP1024(dh2) are
not allowed per default. As of libreswan 4.x, modp1024(dh2) support is no longer
compiled in at all. For IKEv2, the defaults include AES, AES-GCM, DH14 and stronger,
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, for IKE 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 SHA2 as the prf. Note that for phase2alg, there is no prf, so
AES-GCM is specified for ESP as esp=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. These versions are NOT included in the
default and will be removed in a future version, following the recommendation of RFC
8247 or it successor.
Weak algorithms are regularly removed from libreswan. Currently, 1DES and modp768(DH1)
have been removed and modp1024(DH2) has been disabled at compile time. 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. IKEv1 has been disabled per
default, and will soon no longer be compiled in by default.
For all Diffie-Hellman groups, the "dh" keyword can be used instead of the "modp"
keyword. For example ike=3des-sha1;dh19. Diffie-Hellman groups 19,20 and 21 from
RFC-5903 are supported. Curve25519 from RFC-8031 is supported as "dh31". Curve448 and
GOST DH groups are not yet supported in libreswan because these are not supported yet
in the NSS crypto library.
Diffie-Hellman groups 22, 23 and 24 from RFC-5114 are implemented but not compiled in
by default. These DH groups are extremely controversial and MUST NOT be used unless
forced (administratively) by the other party. This is further documented in RFC 8247,
but the summary is that it cannot be proven that these DH groups do not contain a
cryptographic trapdoor (a backdoor by the USG who provided these primes without
revealing the seeds and generation process used).
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
This option is alias to esp.
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.
ms-dh-downgrade
Whether to allow a downgrade of DiffieHellman group during rekey (using
CREATE_CHILD_SA). Microsoft Windows (at the time of writing, Feb 2018) defaults to
using the very weak modp1024 (DH2). This can be changed using a Windows registry
setting to use modp2048 (DH14). However, at rekey times, it will shamelessly use
modp1024 again and the connection might fail. Setting this option to yes (and adding
modp1024 proposals to the ike line) this will allow this downgrade attack to happen.
This should only be used to support Windows that feature this bug. Currently the
accepted values are no, (the default) or yes.
dns-match-id
Whether to perform an additional DNS lookup and confirm the remote ID payload with the
DNS name in the reverse DNS PTR record. Accepted values are no (the default) or yes.
This check should be enabled when Opportunistic IPsec is enabled in a mode that is
based on packet triggers (on-demand) using IPSECKEY records in DNS. Since in that case
the IKE daemon pluto does not know the remote ID, it only knows the remote IP address,
this option forces it to confirm the peer's proposed ID (and thus its public/private
key) with its actual IP address as listed in the DNS. This prevents attacks where
mail.example.com's IP address is taken over by a neighbour machine with a valid
web.example.com setup. This check is not needed for certificate based Opportunistic
IPsec, as "mail.example.com"s certificate does not have an entry for
"web.example.com". It is also not needed for DNS server triggered Opportunistic IPsec,
as in that case the IKE daemon pluto is informed of both the IP address, and the
hostname/public key.
require-id-on-certificate
When using certificates, check whether the IKE peer ID is present as a subjectAltName
(SAN) on the peer certificate. Accepted values are yes (the default) or no. This check
should only be disabled when intentionally using certificates that do not have their
peer ID specified as a SAN on the certificate. These certificates violate RFC 4945
Section 3.1 and are normally rejected to prevent a compromised host from assuming the
IKE identity of another host. The SAN limits the IDs that the peer is able to assume.
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.
PPKs can be used in connections that allow only IKEv2. In libreswan that would mean
that ikev2 option must have value insist. (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
Specifies the algorithms that will be offered/accepted when negotiating a a Child SA.
The general syntax is:
ESP = PROPOSAL[,PROPOSAL...]
PROPOSAL = ENCRYPT_ALGS[-INTEG_ALGS[-DH_ALGS]]
ENCRYPT_ALGS = ENCRYPT_ALG[+ENCRYPT_ALG...]
INTEG_ALGS = INTEG_ALG[+INTEG_ALG...]
DH_ALGS = DH_ALG[+DH_ALG...]
During startup, ipsec_pluto(8) will log all supported ESP algorithms.
Specifying the DH algorithms explicitly is not recommended. When PFS is enabled, and
the DH algorithms are omitted, each PROPOSAL will automatically include the DH
algorithm negotiated during the IKE exchange.
AEAD algorithms such as AES_GCM and AES_CCM no not require a separate integrity
algorithm. For example esp=aes_gcm256 or esp=aes_ccm.
For instance:
esp=aes_gcm,aes128+aes256-sha2_512+sha2_256-dh14+dh19
esp=aes128-sha2_512-dh14+dh19
If not specified, a secure set of defaults will be used. The program:
ipsec algparse esp=...
can be used to query these defaults.
ah
A comma separated list of AH algorithms that will be offered/accepted when negotiating
the Child SA. The general syntax is:
AH = PROPOSAL[,PROPOSAL...]
PROPOSAL = INTEG_ALGS[-DH_ALGS]
INTEG_ALGS = INTEG_ALG[+INTEG_ALG...]
DH_ALGS = DH_ALG[+DH_ALG...]
During startup, ipsec_pluto(8) will log all supported AH algorithms.
Specifying the DH algorithms explicitly is not recommended. When PFS is enabled, and
the DH algorithms are omitted, each PROPOSAL will automatically include the DH
algorithm negotiated during the IKE exchange.
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.
For instance:
ah=sha2_256+sha2_512
ah=sha2_256+sha2_512-dh14+dh19
If not specified, a secure set of defaults will be used. The program:
ipsec algparse ah=...
can be used to query these defaults.
fragmentation
Whether or not to allow IKE fragmentation. Valid values 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 yes,
(the default) and no.
IKE padding is allowed in IKEv1 but has been known to cause interoperability issues.
The ikepad= option can be used to disable IKEv1 padding. This used to be required for
some devices (such as Checkpoint in Aggressive Mode) that reject padded IKEv1 packets.
A bug was fixed in libreswan 3.25 that applied wrong IKE padding in XAUTH, so it is
suspected that Checkpoint padding issue bas been resolved. And this option should not
be needed by anyone. In IKEv2, no padding is allowed, and this option has no effect.
If you find a device that seems to require IKE padding, please contact the libreswan
developers. This option should almost never be enabled and might be removed in a
future version.
ikev2
Whether to use IKEv2 (RFC 7296) or IKEv1 (RFC 4301). Currently the accepted values are
yes (the default), signifying only IKEv2 is accepted, or no, signifying only IKEv1 is
accepted. Previous versions allowed the keywords propose or permit that would allow
either IKEv1 or IKEv2, but this is no longer supported. The permit option is
interpreted as no and the propose option is interpreted as yes. Older versions also
supported keyword insist which is now interpreted as yes.
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. This option
is only implemented for IKEv2. 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 either (the default), yes
and no. If either is specified as an initiator, the responder will make the choice. As
a responder, if either is received, yes is picked.
If replay-window is set to 0, ESN is disabled as some (most?) IPsec stacks won't
support ESN in such a configuration.
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 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 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 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 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.
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 or rsa for RSA Authentication
with SHA-1, rsa-sha2 for RSA-PSS digital signatures based authentication with
SHA2-256, rsa-sha2_384 for RSA-PSS digital signatures based authentication with
SHA2-384, rsa-sha2_512 for RSA-PSS digital signatures based authentication with
SHA2-512, ecdsa for ECDSA 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.
Asymmetric authentication is only supported with IKEv2. If symmetric authentication is
required, use authby= instead of leftauth and 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.
When using EAPONLY authentication, which omits the regular IKEv2 AUTH payload,
leftauth= (or rightauth=) should be set to eaponly.
Be aware that the symmetric keyword is authby= but the asymmetric keyword is leftauth
and rightauth (without the "by").
leftautheap
Whether the security gateways will authenticate uing an EAP method. Acceptable values
are none (the default) and tls for EAPTLS. If EAP is the only authentication method,
set leftauth=none in addition to leftautheap=tls=.
The EAP authentication mechanisms are only available for IKEv2 based connections.
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.
leftikeport
The UDP IKE port to listen on or send data to. This port cannot be 0 or 500. For TCP,
see tcp-remoteport=
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
receiving 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.
enable-tcp
Normally, IKE negotiation and ESP encapsulation happens over UDP. This option enables
support for IKE and ESP over TCP as per RFC 8229. Acceptable values are no(the
default), yes meaning only TCP will be used, or fallback meaning that TCP will be
attempted only after negotiation over UDP failed. Since performance over TCP is much
less, and TCP sessions are vulnerable to simply RST resets and MITM attacks causing
the TCP connection to close, this option should really only be used in fallback mode.
If used in fallback mode, it is recommend to reduce the retransmit-timeout from the
default 60s to a much shorter value such as 10s, so that one does not have to wait a
minute for the TCP fallback to be attempted.
tcp-remoteport
Which remote TCP port to use when IKE over TCP is attempted. The default value is to
use the NAT-T IKE port (4500). This value is not negotiated and should be configured
properly on all endpoints. When opening a TCP socket to the remote host in this port,
a regular ephemeral source port is obtained from the OS. For changing the UDP ports,
see leftikeport=
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: yes (the
default) and no. It is recommended to leave this option set, unless multiple clients
with the same identity are expected to connect using the same subnets and should
operate at the same time. Or if a reconnecting client should not delete its old
instance (eg perhaps it is still running). This is unlikely to be true.
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.
ignore-peer-dns
whether to ignore received DNS configuration. Acceptable values are: no (the default)
and yes. Normally, when a roadwarrior connects to a remote VPN, the remote VPN server
sends a list of DNS domains and DNS nameserver IP addresses that the roadwarrior can
use to reach internal only resources through the VPN. This option allows the
roadwarrior to ignore the server's suggestion. The roadwarrior will normally use this
information to update the DNS resolving process. What is changed depends on the
detected DNS configuration. It can modify /etc/resolv.conf directly, or reconfigure a
locally running DNS server (unbound, knot, stubby or systemd-resolved) or inform
NetworkManager.
accept-redirect
Whether requests of the remote peer to redirect IKE/IPsec SA's are accepted. Valid
options are no (the default) and yes. See also accept-redirect-to.
accept-redirect-to
Specify the comma separated list of addresses we accept being redirected to. Both IPv4
and IPv6 addresses are supported as well the FQDNs. The value %any, as well as not
specifying any address, signifes that we will redirect to any address gateway sends us
in REDIRECT notify payload.
The value of this option is not considered at all if accept-redirect is set to no.
send-redirect
Whether to send requests for the remote peer to redirect IKE/IPsec SA's during
IKE_AUTH. Valid options are no (the default) and yes. If set, the option redirect-to=
must also be set to indicate where to redirect peers to. For redirection during
IKE_SA_INIT exchange, see the global-redirect= and global-redirect-to= options.
Runtime redirects can be triggered via the ipsec whack --redirect command.
redirect-to
Where to send remote peers to via the send-redirect option. This can be an IP address
or hostname (FQDN).
fake-strongswan
whether to send a STRONGSWAN Vendor ID payload to the peer. Acceptable values are: no
(the default) and yes. This used to be required because 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. Note that libreswan and strongswan no longer support twofish or serpent, so
enabling this option likely will no longer do anything.
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 (left|right)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 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 therefore 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.
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); 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. Therefore 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.
ipsec-max-bytes
how many bytes can be sent, or how many bytes can be received on an IPsec SA instance
for a connection; acceptable values are an integer optionally followed by KiB, MiB,
GiB, TiB, PiB or EiB to signify kilobytes, megabytes, gigabytes, terabytes, petabytes
or exabytes.
An IPsec SA contains two keys, one for inbound and one for outbound traffic. The
ipsec-max-bytes sets two limits on each of these keys: the hard limit which is the
total number of bytes that a given key can encrypt, and the soft limit which is the
number of bytes that can be encrypted before a renegotiation of the IPsec SA is
initiated. Normally the renegotiation (via the IKE SA) is completed before the
ipsec-max-bytes value is reached.
Pluto sets the the original initiator's soft limit to 25% of ipsec-max-bytes (with 12%
fuzz) and on the original responder's soft limit to 50% of ipsec-max-bytes (with 12%
fuzz). This way the original initiator hopefully is the one initiating the
renegotiation of the IPsec SA.
This option is not negotiated between IKE peers. Each end of the IPsec SA sets their
own limits independently.
The default (hard limit) is 2^63 bytes. The original initiator's soft limit is 2^61
bytes (approx.) and the original responder's soft limit is 2^62 bytes (approx.).
ipsec-max-packets
how many packets can be sent/received on a particular instance of a connection (a set
of encryption/authentication keys for user packets) , from successful negotiation to
expiry.
Default values and caveats are the same as for ipsec-max-bytes. This option uses a
prefix without "B" for bytes.
replay-window
The size of the IPsec SA replay window protection in packets. Kernels (Linux, and most
BSDs) support a window size of at least 2040 packets. The default replay window size
is 128 packets.
A value 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.
Disabling replay protection will also disable Extended Sequence Numbers (esn=no), as
advise from RFC 4303 caused some stacks to not support ESN without a replay-window.
Note: on Linux, sequence errors can be seen in /proc/net/xfrm_stat.
Note: the BSD setkey utility displays the replay window size in bytes (8 packets per
byte) and not packets.
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 or 0 means to keep trying forever. For Opportunistic Encryption connections,
a keyingtries value of %forever or 0 is set to 1 and a warning message will be logged.
This is because an expired failureshunt triggers new keyingtries on-demand later, when
there is traffic. This prevents accumulating an infinite amount of attempts to peers
that do not support Opportunistic Encryption. For Opportunistic, a keyingtries value
of > 1 is allowed but currently not recommended. The meaning of failureshunt= is
unclear when there is continued (failed) keying happening with a negotiationshunt
installed. Relevant only locally, other end need not agree on it.
ikelifetime
how long the keying channel of a connection (buzzphrase: “IKE SA” or “Parent SA”)
should last before being renegotiated; acceptable values as for salifetime. The
default as of version 4.2 is 8h, before that it was 1h. The maximum is 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).
For IKEv1, compress settings on both peers must match. For IKEv2, compression can only
be suggested and a mismatched compress setting results in connection without
compression.
When set to yes, compression is negotiated for the DEFLATE compression algorithm.
metric
Set the metric for added routes. This value is passed to the _updown scripts as
PLUTO_METRIC. 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 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 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. 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.
ipsec-interface
Create or use an existing virtual interface ipsecXXX for "Routing based VPNs" (as
opposed to "Policy based VPNs"). Valid options are yes, no or a number. When using a
number, the IPsec interface created and/or used will use that number as part of the
interface name. For example setting ipsec-interface=5 will create and/or use the
ipsec5 interface. The value 0 cannot be used and is interpreted as no. The value yes
is interpreted as the number 1, and thus will use the interface named ipsec1. An IP
address can be configured for this interface via the interface-ip= option.
The ipsec-interface is used to route outbound traffic that needs to be encrypted, and
will decrypt inbound traffic that arrives on this interface. All traffic that is
routed to this interface will be automatically encrypted providing the IPsec SA policy
covers this traffic. Traffic not matching the IPsec SA will be dropped. Tools such as
tcpdump, iptables, ifconfig and tools that need traffic counters can be used on all
cleartext pre-encrypt and post-decrypt traffic on the device. When leftsubnet= is
equal to rightsubnet=, the routing needs to be manged by an external routing daemon or
manually by the administrator.
This option is currently only supported on Linux kernels 4.19 or later when compiled
with XFRMi support (CONFIG_XFRM_INTERFACE). The number of the ipsecX device
corresponds with the XFRM IF_ID policy option of the IPsec SA in the Linux kernel. On
Linux, XFRMi interfaces can be managed by libreswan automatically or can be
preconfigured on the system using the existing init system or via networking tools
such as systemd-networkd and NetworkManager. The _updown script handles certain Linux
specific interfaces settings required for proper functioning, such as forwarding and
routing rules for IPsec traffic.
The ipsec-interface=0 will create an interface with the same name as the old KLIPS
interface, ipsec0. This interface name should only be used when required for migration
from KLIPS to XFRM interfaces. Since XFRM IF_ID and marking cannot use 0, this is
mapped to 16384. This means that the devices ipsec0 and ipsec16384 cannot both be in
use.
interface-ip=
NOTE: This option is currently not implemented pending pluto IP address reference
counting. The IP address and netmask to configure on a virtual device (eg ipsecXXX).
This is often used when building Routing based IPsec tunnels using transport mode and
GRE, but can also be useful in other scenarios. Currently requires ipsec-interface=.
See also leftvti= for cnofiguring IP addresses when using VTI.
priority
The priority in the kernel SPD/SAD database, when matching up packets. Each kernel
(XFRM, 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
XFRM 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 XFRM 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.
labeled-ipsec
This option is obsolete. To enable labeled IPsec, setting the policy-label= is enough.
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
logfile=/var/log/pluto.log
plutodebug=all
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 "xfrm" and "bsd".
This option should no longer be set, as the stack is currently auto-detected. The
values "klips, "mast", "netkey", "native", "kame" and "auto" are obsolete. The option
is kept only because it is suspected that Linux and BSD will get userspace stacks with
IPsec support soon (such as dpdk).
listen
IP address to listen on, defaults to ANY. 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.
listen-udp
Whether the pluto IKE daemon should listen on the standard UDP ports of 500 and 4500.
The value "yes" means to listen on these ports, and is the default. This should almost
never be disabled. In the rare case where it is known that only ever TCP or
non-standard UDP ports will be used, this option can disable the standard UDP ports.
Connections can specify their own non-standard port using leftikeport=.
listen-tcp
Whether the pluto IKE daemon should listen on the (pseudo) standard TCP port 4500. The
value "no" is the current default, but this will be changed in the future to "yes".
The TCP usage complies to RFC 8229 for IKE and ESP over TCP support. Connections can
specify their own non-standard port using leftikeport=.
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.
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 (left|right)subnet= for the remote clients
when using the vhost: or vnet: keywords in the (left|right)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.
nhelpers
how many pluto helpers are started to help with cryptographic operations. Pluto will
start as many helpers as the number of CPU's, minus 1 to dedicate to the main thread.
For machines with less than 4 CPU's, an equal number of helpers to CPU's are started.
A value of 0 forces pluto to do all operations inline using 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. Therefore, 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).
ikev1-secctx-attr-type
The value for the IKEv1 IPsec SA security context attribute identifier that 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 option. Labeled IPsec using
IKEv2 does not use this option, it only uses an IANA allocated Notify number. See also
policy-label.
ikev1-policy
What to do with received IKEv1 packets. Valid options are drop (default) which will
silently drop any received IKEv1 packet, accept, and reject which will reply with an
error. If this option is set to drop or reject, an attempt to load an IKEv1 connection
will fail, as these connections would never be able to receive a packet for
processing.
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.
syslog
the syslog(2) “facility” name and priority to use for startup/shutdown log messages,
default daemon.error.
plutodebug
how much Pluto debugging output should be logged. An empty value, or the magic value
none, means no debug output (the default). Otherwise only the specified types of
output (a quoted list, names without the --debug- prefix, separated by white space)
are enabled;
The current option values are base that represents moderate amounts of information,
cpu-usage for getting timing/load based information (best used without any other
debugging options), crypt for all crypto related operations and tmi (Too Much
Information) for excessive logging. To log any sensitive private key or password
material, use the special private value.
The old plutodebug options (control, controlmore, x509, kernel, etc) are mapped to
either base or tmi. Note that all maps to base and not tmi.
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. When using ID of type IP address, this option will not hide the
actual IP address as part of the ID. Most deployments will not want to change this
from the default. If logging of IP addresses is unwanted, audit-log=no should also be
set.
audit-log
Whether pluto should produce Linux Auditing System log messages. If enabled, pluto
will log start, stop and fail for the negotiation of IKE and IPsec SA's. The kernel
will also log success and failures for actually adding and removing IPsec SA's from
the kernel's SADB. Valid options are yes(the default) and no. On non-Linux systems,
this option is ignored. If enabled but the kernel is lacking audit support, audit
messages are not sent. If the kernel has audit support and using it fails, pluto will
abort. Note that for compliance reasons, audit log messages contain the relevant IP
addresses, even if logip=no.
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=
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.
global-redirect
Whether to send requests for the remote peer to redirect IKE/IPsec SA's during
IKE_SA_INIT. Valid options are no (the default), yes and auto, where auto means that
the requests will be sent if DDoS mode is active (see ddos-mode). If set, the option
global-redirect-to= must also be set to indicate where to redirect peers to. For
specific connection redirection after IKE SA authentication, see the send-redirect=
and redirect-to= options. This configuration can be changed at runtime via the ipsec
whack --global-redirect command.
global-redirect-to
Where to send remote peers to via the global-redirect option. This can be a list, or a
single entry, of IP addresses or hostnames (FQDNs). If there is a list of entries,
they must be separated with comma's. One specified entry means all peers will be
redirected to it, while multiple specified entries means peers will be evenly
distributed across the specified servers. This configuration can be changed at runtime
via the ipsec whack --global-redirect-to command.
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 XFRM acquire state times out. The default value is 30
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.
nssdir
Specifies a directory for NSS database files. The default value is /var/lib/ipsec/nss.
It may contain the following files:
pkcs11.txt
Detailed info about NSS database creation parameteres.
cert9.db
NSS Certificate database.
key4.db
NSS Key database.
When SELinux runs in enforced mode, changing this requires a similar change in the
SELinux policy for the pluto daemon.
secretsfile
pathname of the file that stores the secret credentials such as preshared keys (PSKs).
See man ipsec.secrets for the syntax. The default value is /etc/ipsec.secrets.
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.
dnssec-enable
Whether pluto should perform dnssec validation using libunbound, provided libreswan
was compiled with USE_DNSSEC. A value of yes (the default) means pluto should perform
DNSSEC validation. Note that pluto reads the file /etc/resolv.conf to determine which
nameservers to use.
dnssec-rootkey-file
The location of the DNSSEC root zone public key file. The default is
/var/lib/unbound/root.key but this can be changed at compile time.
dnssec-anchors
The location of a file containing additional DNSSEC Trust Anchors. This can be used
when a network is using split-DNS and the internal hierarchy is using DNSSEC trust
anchors. There is no default value.
OPPORTUNISTIC CONNS
For Opportunistic connections, the system requires creating special named conns that are
used to implement the default policy groups. Currently, these names cannot be changed.
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
These conns will only work if %defaultroute works. The leftid will be the interfaces IP
address by default, but it can also be set to %fromcert or use a DNS name.
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 that has right=%group or right=%opportunisticgroup is a policy
group connection. When a policy group file of the same name is loaded 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.
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 that 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_auto(8), ipsec_rsasigkey(8)
HISTORY
Designed for the FreeS/WAN project <https://www.freeswan.org> by Henry Spencer.
BUGS
Before reporting new bugs, please ensure you are using the latest version of Libreswan.
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.
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.
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