.TH IPSEC.CONF 5 "2012-06-26" "@PACKAGE_VERSION@" "strongSwan"
.SH NAME
ipsec.conf \- IPsec configuration and connections
.SH DESCRIPTION
The optional
.I ipsec.conf
file
specifies most configuration and control information for the
strongSwan IPsec subsystem.
The major exception is secrets for authentication;
see
.IR ipsec.secrets (5).
Its contents are not security-sensitive.
.PP
The file is a text file, consisting of one or more
.IR sections .
White space followed by
.B #
followed by anything to the end of the line
is a comment and is ignored,
as are empty lines which are not within a section.
.PP
A line which contains
.B include
and a file name, separated by white space,
is replaced by the contents of that file.
If the file name is not a full pathname,
it is considered to be relative to the directory containing the
including file.
Such inclusions can be nested.
Only a single filename may be supplied, and it may not contain white space,
but it may include shell wildcards (see
.IR sh (1));
for example:
.PP
.B include
.B "ipsec.*.conf"
.PP
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
.B also
parameter (described below) which permits splitting a single logical
section (e.g. a connection description) into several actual sections.
.PP
A section
begins with a line of the form:
.PP
.I type
.I name
.PP
where
.I type
indicates what type of section follows, and
.I name
is an arbitrary name which distinguishes the section from others
of the same type.
All subsequent non-empty lines
which begin with white space are part of the section.
Sections of the same type that share the same name are merged.
.PP
Lines within the section are generally of the form
.PP
\ \ \ \ \ \fIparameter\fB=\fIvalue\fR
.PP
(note the mandatory preceding white space).
There can be white space on either side of the
.BR = .
Parameter names are specific to a section type.
.PP
An empty
.I value
stands for the system default value (if any) of the parameter,
i.e. it is roughly equivalent to omitting the parameter line entirely. This may
be useful to clear a setting inherited from a
.B %default
section or via
.B also
parameter (see below).
A
.I value
may contain single spaces (additional white space is reduced to one space).
To preserve white space as written enclose the entire
.I value
in double quotes (\fB"\fR); in such values double quotes themselves may be
escaped by prefixing them with
.B \\\\
characters. A double-quoted string may span multiple lines by ending them with
.B \\\\
characters (following lines don't have to begin with white space, as that will
be preserved). Additionally, the following control characters may be encoded in
double-quoted strings: \\n, \\r, \\t, \\b, \\f.
.PP
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).
.PP
There is currently one parameter which is available in any type of
section:
.TP
.B also
the value is a section name; the parameters of that section are inherited by
the current section. Parameters in the current section always override inherited
parameters, even if an
.B also
follows after them.
The specified section must exist and must have the same section type; it doesn't
if it is defined before or after the current section.
Nesting is permitted, and there may be more than one
.B also
in a single section (parameters from referenced sections are inherited and
overridden in the order of these
.B also
parameters).
.PP
A section with name
.B %default
specifies defaults for sections of the same type. All parameters in it, are
inherited by all other sections of that type.
.PP
Currently there are three types of sections:
a
.B config
section specifies general configuration information for IPsec, a
.B conn
section specifies an IPsec connection, while a
.B ca
section specifies special properties of a certification authority.
.SH "CONN SECTIONS"
A
.B conn
section contains a
.IR "connection specification" ,
defining a network connection to be made using IPsec.
The name given is arbitrary, and is used to identify the connection.
Here's a simple example:
.PP
.ne 10
.nf
.ft B
.ta 1c
conn snt
	left=192.168.0.1
	leftsubnet=10.1.0.0/16
	right=192.168.0.2
	rightsubnet=10.1.0.0/16
	keyingtries=%forever
	auto=add
.ft
.fi
.PP
A note on terminology: 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 path to control the connection is called 'ISAKMP SA' in IKEv1
and 'IKE SA' in the IKEv2 protocol. That what is being negotiated, the kernel
level data path, is called 'IPsec SA' or 'Child SA'.
strongSwan previously used two separate keying daemons, \fIpluto\fP and
\fIcharon\fP. This manual does not discuss \fIpluto\fP options anymore, but
only \fIcharon\fP that since strongSwan 5.0 supports both IKEv1 and IKEv2.
.PP
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
.I left
and
.I right
participants,
rather than in terms of local and remote.
Which participant is considered
.I left
or
.I right
is arbitrary;
for every connection description an attempt is made to figure out whether
the local endpoint should act as the
.I left
or
.I right
endpoint. This is done by matching the IP addresses defined for both endpoints
with the IP addresses assigned to local network interfaces. If a match is found
then the role (left or right) that matches is going to be considered local.
If no match is found during startup,
.I left
is considered local.
This permits using identical connection specifications on both ends.
There are cases where there is no symmetry; a good convention is to
use
.I left
for the local side and
.I right
for the remote side (the first letters are a good mnemonic).
.PP
Many of the parameters relate to one participant or the other;
only the ones for
.I left
are listed here, but every parameter whose name begins with
.B left
has a
.B right
counterpart,
whose description is the same but with
.B left
and
.B right
reversed.
.PP
Parameters are optional unless marked '(required)'.
.SS "CONN PARAMETERS"
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.
.TP
.BR aaa_identity " = <id>"
defines the identity of the AAA backend used during IKEv2 EAP authentication.
This is required if the EAP client uses a method that verifies the server
identity (such as EAP-TLS), but it does not match the IKEv2 gateway identity.
.TP
.BR aggressive " = yes | " no
whether to use IKEv1 Aggressive or Main Mode (the default).
.TP
.BR ah " = <cipher suites>"
comma-separated list of AH algorithms to be used for the connection, e.g.
.BR sha1-sha256-modp1024 .
The notation is
.BR integrity[-dhgroup] .
For IKEv2, multiple algorithms (separated by -) of the same type can be included
in a single proposal. IKEv1 only includes the first algorithm in a proposal.
Only either the
.B ah
or
.B esp
keyword may be used, AH+ESP bundles are not supported.

There is no default AH cipher suite since by default ESP is used.
The daemon adds its extensive default proposal to the configured value. To
restrict it to the configured proposal an
exclamation mark
.RB ( ! )
can be added at the end.

If
.B dh-group
is specified, CHILD_SA/Quick Mode setup and rekeying include a separate
Diffie-Hellman exchange (refer to the
.B esp
keyword for details).
.TP
.BR also " = <name>"
includes conn section
.BR <name> .
.TP
.BR auth " = <value>"
was used by the
.B pluto
IKEv1 daemon to use AH integrity protection for ESP encrypted packets, but is
not supported in charon. The
.B ah
keyword specifies algorithms to use for integrity protection with AH, but
without encryption. AH+ESP bundles are not supported.
.TP
.BR authby " = " pubkey " | rsasig | ecdsasig | psk | secret | never | xauthpsk | xauthrsasig"
how the two security gateways should authenticate each other;
acceptable values are
.B psk
or
.B secret
for pre-shared secrets,
.B pubkey
(the default) for public key signatures as well as the synonyms
.B rsasig
for RSA digital signatures and
.B ecdsasig
for Elliptic Curve DSA signatures.
.B never
can be used if negotiation is never to be attempted or accepted (useful for
shunt-only conns).
Digital signatures are superior in every way to shared secrets.
IKEv1 additionally supports the values
.B xauthpsk
and
.B xauthrsasig
that will enable eXtended AUTHentication (XAUTH) in addition to IKEv1 main mode
based on shared secrets or digital RSA signatures, respectively.
This parameter is deprecated, as two peers do not need to agree on an
authentication method in IKEv2. Use the
.B leftauth
parameter instead to define authentication methods.
.TP
.BR auto " = " ignore " | add | route | start"
what operation, if any, should be done automatically at IPsec startup;
currently-accepted values are
.BR add ,
.BR route ,
.B start
and
.B ignore
(the default).
.B add
loads a connection without starting it.
.B route
loads a connection and installs kernel traps. If traffic is detected between
.B leftsubnet
and
.BR rightsubnet ,
a connection is established.
.B start
loads a connection and brings it up immediately.
.B ignore
ignores the connection. This is equal to deleting a connection from the config
file.
Relevant only locally, other end need not agree on it.
.TP
.BR closeaction " = " none " | clear | hold | restart"
defines the action to take if the remote peer unexpectedly closes a CHILD_SA
(see
.B dpdaction
for meaning of values).
A
.B closeaction should not be
used if the peer uses reauthentication or uniquids checking, as these events
might trigger the defined action when not desired.
.TP
.BR compress " = yes | " no
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 \fIbefore\fR encryption);
acceptable values are
.B yes
and
.B no
(the default). A value of
.B yes
causes the daemon to propose both compressed and uncompressed,
and prefer compressed.
A value of
.B no
prevents the daemon from proposing or accepting compression.
.TP
.BR dpdaction " = " none " | clear | hold | restart"
controls the use of the Dead Peer Detection protocol (DPD, RFC 3706) where
R_U_THERE notification messages (IKEv1) or empty INFORMATIONAL messages (IKEv2)
are periodically sent in order to check the
liveliness of the IPsec peer. The values
.BR clear ,
.BR hold ,
and
.B restart
all activate DPD and determine the action to perform on a timeout. With
.B clear
the connection is closed with no further actions taken.
.B hold
installs a trap policy, which will catch matching traffic and tries to
re-negotiate the connection on demand.
.B restart
will immediately trigger an attempt to re-negotiation the connection.
The default is
.B none
which disables the active sending of DPD messages.
.TP
.BR dpddelay " = " 30s " | <time>"
defines the period time interval with which R_U_THERE messages/INFORMATIONAL
exchanges are sent to the peer. These are only sent if no other traffic is
received. In IKEv2, a value of 0 sends no additional INFORMATIONAL
messages and uses only standard messages (such as those to rekey) to detect
dead peers.
.TP
.BR dpdtimeout " = " 150s " | <time>
defines the timeout interval, after which all connections to a peer are deleted
in case of inactivity. This only applies to IKEv1, in IKEv2 the default
retransmission timeout applies, as every exchange is used to detect dead peers.
.TP
.BR inactivity " = <time>"
defines the timeout interval, after which a CHILD_SA is closed if it did
not send or receive any traffic. The inactivity counter is reset during CHILD_SA
rekeying. This means that the inactivity timeout must be smaller than the
rekeying interval to have any effect.
.TP
.BR eap_identity " = <id>"
defines the identity the client uses to reply to an EAP Identity request.
If defined on the EAP server, the defined identity will be used as peer
identity during EAP authentication. The special value
.B %identity
uses the EAP Identity method to ask the client for an EAP identity. If not
defined, the IKEv2 identity will be used as EAP identity.
.TP
.BR esp " = <cipher suites>"
comma-separated list of ESP encryption/authentication algorithms to be used
for the connection, e.g.
.BR aes128-sha256 .
The notation is
.BR encryption-integrity[-dhgroup][-esnmode] .
For IKEv2, multiple algorithms (separated by -) of the same type can be included
in a single proposal. IKEv1 only includes the first algorithm in a proposal.
Only either the
.B ah
or
.B esp
keyword may be used, AH+ESP bundles are not supported.

Defaults to
.BR aes128-sha256 .
The daemon adds its extensive default proposal to this default
or the configured value.  To restrict it to the configured proposal an
exclamation mark
.RB ( ! )
can be added at the end.

.BR Note :
As a responder, the daemon defaults to selecting the first configured proposal
that's also supported by the peer. This may be changed via
.BR strongswan.conf (5)
to selecting the first acceptable proposal sent by the peer instead. In order to
restrict a responder to only accept specific cipher suites, the strict flag
.RB ( ! ,
exclamation mark) can be used, e.g: aes256-sha512-modp4096!

If
.B dh-group
is specified, CHILD_SA/Quick Mode rekeying and initial negotiation use a
separate Diffie-Hellman exchange using the specified group. However, for IKEv2,
the keys of the CHILD_SA created implicitly with the IKE_SA will always be
derived from the IKE_SA's key material. So any DH group specified here will only
apply when the CHILD_SA is later rekeyed or is created with a separate
CREATE_CHILD_SA exchange.  Therefore, a proposal mismatch might not immediately
be noticed when the SA is established, but may later cause rekeying to fail.

Valid values for
.B esnmode
are
.B esn
and
.BR noesn .
Specifying both negotiates Extended Sequence Number support with the peer,
the default is
.B noesn.
.TP
.BR forceencaps " = yes | " no
force UDP encapsulation for ESP packets even if no NAT situation is detected.
This may help to surmount restrictive firewalls. In order to force the peer to
encapsulate packets, NAT detection payloads are faked.
.TP
.BR fragmentation " = " yes "  | accept | force | no"
whether to use IKE fragmentation (proprietary IKEv1 extension or IKEv2
fragmentation as per RFC 7383).  Acceptable values are
.B yes
(the default),
.BR accept ,
.B force
and
.BR no .
If set to
.BR yes ,
and the peer supports it, oversized IKE messages will be sent in fragments. If
set to
.BR accept ,
support for fragmentation is announced to the peer but the daemon does not send
its own messages in fragments. If set to
.B force
(only supported for IKEv1) the initial IKE message will already be fragmented
if required. Finally, setting the option to
.B no
will disable announcing support for this feature.

Note that fragmented IKE messages sent by a peer are always accepted
irrespective of the value of this option (even when set to
.BR no ).
.TP
.BR ike " = <cipher suites>"
comma-separated list of IKE/ISAKMP SA encryption/authentication algorithms
to be used, e.g.
.BR aes128-sha256-modp3072 .
The notation is
.BR encryption-integrity[-prf]-dhgroup .
If no PRF is given, the algorithms defined for integrity are used for the PRF.
The prf keywords are the same as the integrity algorithms, but have a
.B prf
prefix (such as
.BR prfsha1 ,
.B prfsha256
or
.BR prfaesxcbc ).
.br
In IKEv2, multiple algorithms and proposals may be included, such as
.BR aes128-aes256-sha1-modp3072-modp2048,3des-sha1-md5-modp1024 .

Defaults to
.BR aes128-sha256-modp3072 .
The daemon adds its extensive default proposal to this
default or the configured value.  To restrict it to the configured proposal an
exclamation mark
.RB ( ! )
can be added at the end.

.BR Note :
As a responder the daemon accepts the first supported proposal received from
the peer.  In order to restrict a responder to only accept specific cipher
suites, the strict flag
.RB ( ! ,
exclamation mark) can be used, e.g:
.BR aes256-sha512-modp4096!
.TP
.BR ikedscp " = " 000000 " | <DSCP field>"
Differentiated Services Field Codepoint to set on outgoing IKE packets sent
from this connection. The value is a six digit binary encoded string defining
the Codepoint to set, as defined in RFC 2474.
.TP
.BR ikelifetime " = " 3h " | <time>"
how long the keying channel of a connection (ISAKMP or IKE SA)
should last before being renegotiated. Also see EXPIRY/REKEY below.
.TP
.BR installpolicy " = " yes " | no"
decides whether IPsec policies are installed in the kernel by the charon daemon
for a given connection. Allows peaceful cooperation e.g. with
the Mobile IPv6 daemon mip6d who wants to control the kernel policies.
Acceptable values are
.B yes
(the default) and
.BR no .
.TP
.BR keyexchange " = " ike " | ikev1 | ikev2"
which key exchange protocol should be used to initiate the connection.
Connections marked with
.B ike
use IKEv2 when initiating, but accept any protocol version when responding.
.TP
.BR keyingtries " = " 3 " | <number> | %forever"
how many attempts (a whole number or \fB%forever\fP) should be made to
negotiate a connection, or a replacement for one, before giving up
(default
.BR 3 ).
The value \fB%forever\fP
means 'never give up'.
Relevant only locally, other end need not agree on it.
.TP
.B keylife
synonym for
.BR lifetime .
.TP
.BR left " = <ip address> | <fqdn> | " %any " | <range> | <subnet> "
The IP address of the left participant's public-network interface
or one of several magic values.
The value
.B %any
(the default) for the local endpoint signifies an address to be filled in (by
automatic keying) during negotiation. If the local peer initiates the
connection setup the routing table will be queried to determine the correct
local IP address.
In case the local peer is responding to a connection setup then any IP address
that is assigned to a local interface will be accepted.

The prefix
.B %
in front of a fully-qualified domain name or an IP address will implicitly set
.BR leftallowany =yes.

If
.B %any
is used for the remote endpoint it literally means any IP address.

If an
.B FQDN
is assigned it is resolved every time a configuration lookup is done. If DNS
resolution times out, the lookup is delayed for that time.

To limit the connection to a  specific range of hosts, a range (
.BR 10.1.0.0-10.2.255.255
) or a subnet (
.BR 10.1.0.0/16
) can be specified, and multiple addresses, ranges and subnets can be separated
by commas. While one can freely combine these items, to initiate the connection
at least one non-range/subnet is required.

Please note that with the usage of wildcards multiple connection descriptions
might match a given incoming connection attempt. The most specific description
is used in that case.
.TP
.BR leftallowany " = yes | " no
a modifier for
.BR left ,
making it behave as
.B %any
although a concrete IP address or domain name has been assigned.
.TP
.BR leftauth " = <auth method>"
Authentication method to use locally (left) or require from the remote (right)
side.
Acceptable values are
.B pubkey
for public key authentication (RSA/ECDSA),
.B psk
for pre-shared key authentication,
.B eap
to (require the) use of the Extensible Authentication Protocol in IKEv2, and
.B xauth
for IKEv1 eXtended Authentication.

To require a trustchain public key strength for the remote side, specify the
key type followed by the minimum strength in bits (for example
.BR ecdsa-384
or
.BR rsa-2048-ecdsa-256 ).
To limit the acceptable set of hashing algorithms for trustchain validation,
append hash algorithms to
.BR pubkey
or a key strength definition (for example
.BR pubkey-sha1-sha256
or
.BR rsa-2048-ecdsa-256-sha256-sha384-sha512 ).
Unless disabled in
.BR strongswan.conf (5),
or explicit IKEv2 signature constraints are configured (see below), such key
types and hash algorithms are also applied as constraints against IKEv2
signature authentication schemes used by the remote side.

If both peers support RFC 7427 ("Signature Authentication in IKEv2") specific
hash algorithms to be used during IKEv2 authentication may be configured.
The syntax is the same as above, but with ike: prefix. For example, with
.B ike:pubkey-sha384-sha256
a public key signature scheme with either SHA-384 or SHA-256 would get used for
authentication, in that order and depending on the hash algorithms supported by
the peer.  If no specific hash algorithms are configured, the default is to
prefer an algorithm that matches or exceeds the strength of the signature key.
If no constraints with ike: prefix are configured any signature scheme
constraint (without ike: prefix) will also apply to IKEv2 authentication, unless
this is disabled in
.BR strongswan.conf (5).

For
.BR eap ,
an optional EAP method can be appended. Currently defined methods are
.BR eap-aka ,
.BR eap-gtc ,
.BR eap-md5 ,
.BR eap-mschapv2 ,
.BR eap-peap ,
.BR eap-sim ,
.BR eap-tls ,
.BR eap-ttls ,
.BR eap-dynamic ,
and
.BR eap-radius .
Alternatively, IANA assigned EAP method numbers are accepted. Vendor specific
EAP methods are defined in the form
.B eap-type-vendor
.RB "(e.g. " eap-7-12345 ).
To specify signature and trust chain constraints for EAP-(T)TLS, append a colon
to the EAP method, followed by the key type/size and hash algorithm as discussed
above. For
.B xauth,
an XAuth authentication backend can be specified, such as
.B xauth-generic
or
.BR xauth-eap .
If XAuth is used in
.BR leftauth ,
Hybrid authentication is used. For traditional XAuth authentication, define
XAuth in
.BR lefauth2 .
.TP
.BR leftauth2 " = <auth method>"
Same as
.BR leftauth ,
but defines an additional authentication exchange. In IKEv1, only XAuth can be
used in the second authentication round. IKEv2 supports multiple complete
authentication rounds using "Multiple Authentication Exchanges" defined
in RFC 4739. This allows, for example, separated authentication
of host and user.
.TP
.BR leftca " = <issuer dn> | %same"
the distinguished name of a certificate authority which is required to
lie in the trust path going from the left participant's certificate up
to the root certification authority.
.B %same
means that the value configured for the right participant should be reused.
.TP
.BR leftca2 " = <issuer dn> | %same"
Same as
.BR leftca ,
but for the second authentication round (IKEv2 only).
.TP
.BR leftcert " = <path>"
the path to the left participant's X.509 certificate. The file can be encoded
either in PEM or DER format. OpenPGP certificates are supported as well.
Both absolute paths or paths relative to \fI/etc/ipsec.d/certs\fP
are accepted. By default
.B leftcert
sets
.B leftid
to the distinguished name of the certificate's subject.
The left participant's ID can be overridden by specifying a
.B leftid
value which must be certified by the certificate, though.
.br
A value in the form
.B %smartcard[<slot nr>[@<module>]]:<keyid>
defines a specific certificate to load from a PKCS#11 backend for this
connection. See ipsec.secrets(5) for details about smartcard definitions.
.B leftcert
is required only if selecting the certificate with
.B leftid
is not sufficient, for example if multiple certificates use the same subject.
.br
Multiple certificate paths or PKCS#11 backends can be specified in a comma
separated list. The daemon chooses the certificate based on the received
certificate requests if possible before enforcing the first.
.TP
.BR leftcert2 " = <path>"
Same as
.B leftcert,
but for the second authentication round (IKEv2 only).
.TP
.BR leftcertpolicy " = <OIDs>"
Comma separated list of certificate policy OIDs the peer's certificate must
have.
OIDs are specified using the numerical dotted representation.
.TP
.BR leftdns " = <servers>"
Comma separated list of DNS server addresses to exchange as configuration
attributes. On the initiator, a server is a fixed IPv4/IPv6 address, or
.BR %config4 / %config6
to request attributes without an address. On the responder,
only fixed IPv4/IPv6 addresses are allowed and define DNS servers assigned
to the client.
.TP
.BR leftfirewall " = yes | " no
whether the left participant is doing forwarding-firewalling
(including masquerading) using iptables for traffic from \fIleftsubnet\fR,
which should be turned off (for traffic to the other subnet)
once the connection is established;
acceptable values are
.B yes
and
.B no
(the default).
May not be used in the same connection description with
.BR leftupdown .
Implemented as a parameter to the default \fBipsec _updown\fR script.
See notes below.
Relevant only locally, other end need not agree on it.

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 \fBipsec _updown\fR script.

In situations calling for more control,
it may be preferable for the user to supply his own
.I updown
script,
which makes the appropriate adjustments for his system.
.TP
.BR leftgroups " = <group list>"
a comma separated list of group names. If the
.B leftgroups
parameter is present then the peer must be a member of at least one
of the groups defined by the parameter.
.TP
.BR leftgroups2 " = <group list>"
Same as
.B leftgroups,
but for the second authentication round defined with
.B leftauth2.
.TP
.BR lefthostaccess " = yes | " no
inserts a pair of INPUT and OUTPUT iptables rules using the default
\fBipsec _updown\fR script, thus allowing access to the host itself
in the case where the host's internal interface is part of the
negotiated client subnet.
Acceptable values are
.B yes
and
.B no
(the default).
.TP
.BR leftid " = <id>"
how the left participant should be identified for authentication;
defaults to
.B left
or the subject of the certificate configured with
.BR leftcert .
If
.B leftcert
is configured the identity has to be confirmed by the certificate.

Can be an IP address, a fully-qualified domain name, an email address or a
Distinguished Name for which the ID type is determined automatically and the
string is converted to the appropriate encoding. The rules for this conversion
are described in IDENTITY PARSING below.

In certain special situations the identity parsing above might be inadequate
or produce the wrong result. Examples are the need to encode a FQDN as KEY_ID or
the string parser being unable to produce the correct binary ASN.1 encoding of
a certificate's DN.  For these situations it is possible to enforce a specific
identity type and to provide the binary encoding of the identity. To do this a
prefix may be used, followed by a colon (:). If the number sign (#) follows the
colon, the remaining data is interpreted as hex encoding, otherwise the string
is used as is as the identification data.
.BR Note :
The latter implies that no conversion is performed for non-string identities.
For example,
\fIipv4:10.0.0.1\fP does not create a valid ID_IPV4_ADDR IKE identity, as it
does not get converted to binary 0x0a000001. Instead, one could use
\fIipv4:#0a000001\fP to get a valid identity, but just using the implicit type
with automatic conversion is usually simpler. The same applies to the ASN.1
encoded types. The following prefixes are known:
.BR ipv4 ,
.BR ipv6 ,
.BR rfc822 ,
.BR email ,
.BR userfqdn ,
.BR fqdn ,
.BR dns ,
.BR asn1dn ,
.B asn1gn
and
.BR keyid .
Custom type prefixes may be specified by surrounding the numerical type value by
curly brackets.

For IKEv2 and
.B rightid
the prefix
.B %
in front of the identity prevents the daemon from sending IDr in its IKE_AUTH
request and will allow it to verify the configured identity against the subject
and subjectAltNames contained in the responder's certificate (otherwise it is
only compared with the IDr returned by the responder).  The IDr sent by the
initiator might otherwise prevent the responder from finding a config if it
has configured a different value for
.BR leftid .
.TP
.BR leftid2 " = <id>"
identity to use for a second authentication for the left participant
(IKEv2 only); defaults to
.BR leftid .
.TP
.BR leftikeport " = <port>"
UDP port the left participant uses for IKE communication.
If unspecified, port 500 is used with the port floating
to 4500 if a NAT is detected or MOBIKE is enabled. Specifying a local IKE port
different from the default additionally requires a socket implementation that
listens on this port.
.TP
.BR leftprotoport " = <protocol>/<port>"
restrict the traffic selector to a single protocol and/or port. This option
is now deprecated, protocol/port information can be defined for each subnet
directly in
.BR leftsubnet .
.TP
.BR leftsigkey " = <raw public key> | <path to public key>"
the left participant's public key for public key signature authentication,
in PKCS#1 format using hex (0x prefix) or base64 (0s prefix) encoding. With the
optional
.B dns:
or
.B ssh:
prefix in front of 0x or 0s, the public key is expected to be in either
the RFC 3110 (not the full RR, only RSA key part) or RFC 4253 public key format,
respectively.
Also accepted is the path to a file containing the public key in PEM, DER or SSH
encoding. Both absolute paths or paths relative to \fI/etc/ipsec.d/certs\fP
are accepted.
.TP
.BR leftsendcert " = never | no | " ifasked " | always | yes"
Accepted values are
.B never
or
.BR no ,
.B always
or
.BR yes ,
and
.BR ifasked " (the default),"
the latter meaning that the peer must send a certificate request payload in
order to get a certificate in return.
.TP
.BR leftsourceip " = %config4 | %config6 | <ip address>"
Comma separated list of internal source IPs to use in a tunnel, also known as
virtual IP. If the value is one of the synonyms
.BR %config ,
.BR %cfg ,
.BR %modeconfig ,
or
.BR %modecfg ,
an address (from the tunnel address family) is requested from the peer. With
.B %config4
and
.B %config6
an address of the given address family will be requested explicitly.
If an IP address is configured, it will be requested from the responder,
which is free to respond with a different address.
.TP
.BR rightsourceip " = %config | <network>/<netmask> | <from>-<to> | %poolname"
Comma separated list of internal source IPs to use in a tunnel for the remote
peer. If the value is
.B %config
on the responder side, the initiator must propose an address which is then
echoed back. Also supported are address pools expressed as
\fInetwork\fB/\fInetmask\fR
and
\fIfrom\fB-\fIto\fR
or the use of an external IP address pool using %\fIpoolname\fR,
where \fIpoolname\fR is the name of the IP address pool used for the lookup.
.TP
.BR leftsubnet " = <ip subnet>[[<proto/port>]][,...]"
private subnet behind the left participant, expressed as
\fInetwork\fB/\fInetmask\fR;
if omitted, essentially assumed to be \fIleft\fB/32\fR,
signifying that the left end of the connection goes to the left participant
only. Configured subnets of the peers may differ, the protocol narrows it to
the greatest common subnet. In IKEv1, this may lead to problems with other
implementations, make sure to configure identical subnets in such
configurations. IKEv2 supports multiple subnets separated by commas. IKEv1 only
interprets the first subnet of such a definition, unless the Cisco Unity
extension plugin is enabled. This is due to a limitation of the IKEv1 protocol,
which only allows a single pair of subnets per CHILD_SA. So to tunnel several
subnets a conn entry has to be defined and brought up for each pair of subnets.

The optional part after each subnet enclosed in square brackets specifies a
protocol/port to restrict the selector for that subnet.

Examples:
.BR leftsubnet=10.0.0.1[tcp/http],10.0.0.2[6/80] " or"
.BR leftsubnet=fec1::1[udp],10.0.0.0/16[/53] .
Instead of omitting either value
.B %any
can be used to the same effect, e.g.
.BR leftsubnet=fec1::1[udp/%any],10.0.0.0/16[%any/53] .

If the protocol is
.B icmp
or
.B ipv6-icmp
the port is interpreted as ICMP message type if it is less than 256 or as type
and code if it is greater or equal to 256, with the type in the most significant
8 bits and the code in the least significant 8 bits.

The port value can alternatively take the value
.B %opaque
for RFC 4301 OPAQUE selectors, or a numerical range in the form
.BR 1024-65535 .
None of the kernel backends currently supports opaque or port ranges and uses
.B %any
for policy installation instead.

Instead of specifying a subnet,
.B %dynamic
can be used to replace it with the IKE address, having the same effect
as omitting
.B leftsubnet
completely. Using
.B %dynamic
can be used to define multiple dynamic selectors, each having a potentially
different protocol/port definition.

.TP
.BR leftupdown " = <path>"
what ``updown'' script to run to adjust routing and/or firewalling
when the status of the connection
changes (default
.BR "ipsec _updown" ).
May include positional parameters separated by white space
(although this requires enclosing the whole string in quotes);
including shell metacharacters is unwise.
Relevant only locally, other end need not agree on it. Charon uses the updown
script to insert firewall rules only, since routing has been implemented
directly into the daemon.
.TP
.BR lifebytes " = <number>"
the number of bytes transmitted over an IPsec SA before it expires.
.TP
.BR lifepackets " = <number>"
the number of packets transmitted over an IPsec SA before it expires.
.TP
.BR lifetime " = " 1h " | <time>"
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
.BR s
(a time in seconds)
or a decimal number followed by
.BR m ,
.BR h ,
or
.B d
(a time
in minutes, hours, or days respectively)
(default
.BR 1h ,
maximum
.BR 24h ).
Normally, the connection is renegotiated (via the keying channel)
before it expires (see
.BR margintime ).
The two ends need not exactly agree on
.BR lifetime ,
although if they do not,
there will be some clutter of superseded connections on the end
which thinks the lifetime is longer. Also see EXPIRY/REKEY below.
.TP
.BR marginbytes " = <number>"
how many bytes before IPsec SA expiry (see
.BR lifebytes )
should attempts to negotiate a replacement begin.
.TP
.BR marginpackets " = <number>"
how many packets before IPsec SA expiry (see
.BR lifepackets )
should attempts to negotiate a replacement begin.
.TP
.BR margintime " = " 9m " | <time>"
how long before connection expiry or keying-channel expiry
should attempts to
negotiate a replacement
begin; acceptable values as for
.B lifetime
(default
.BR 9m ).
Relevant only locally, other end need not agree on it. Also see EXPIRY/REKEY
below.
.TP
.BR mark " = <value>[/<mask>]"
sets an XFRM mark in the inbound and outbound
IPsec SAs and policies. If the mask is missing then a default
mask of
.B 0xffffffff
is assumed. The special value
.B %unique
assigns a unique value to each newly created IPsec SA.
.TP
.BR mark_in " = <value>[/<mask>]"
sets an XFRM mark in the inbound IPsec SA and
policy. If the mask is missing then a default mask of
.B 0xffffffff
is assumed.
.TP
.BR mark_out " = <value>[/<mask>]"
sets an XFRM mark in the outbound IPsec SA and
policy. If the mask is missing then a default mask of
.B 0xffffffff
is assumed.
.TP
.BR mobike " = " yes " | no"
enables the IKEv2 MOBIKE protocol defined by RFC 4555. Accepted values are
.B yes
(the default) and
.BR no .
If set to
.BR no ,
the charon daemon will not actively propose MOBIKE as initiator and
ignore the MOBIKE_SUPPORTED notify as responder.
.TP
.BR modeconfig " = push | " pull
defines which mode is used to assign a virtual IP.
Accepted values are
.B push
and
.B pull
(the default).
Push mode is currently not supported with IKEv2.
The setting must be the same on both sides.
.TP
.BR reauth " = " yes " | no"
whether rekeying of an IKE_SA should also reauthenticate the peer. In IKEv1,
reauthentication is always done. In IKEv2, a value of
.B no
rekeys without uninstalling the IPsec SAs, a value of
.B yes
(the default) creates a new IKE_SA from scratch and tries to recreate
all IPsec SAs.
.TP
.BR rekey " = " yes " | no"
whether a connection should be renegotiated when it is about to expire;
acceptable values are
.B yes
(the default)
and
.BR no .
The two ends need not agree, but while a value of
.B no
prevents charon from requesting renegotiation,
it does not prevent responding to renegotiation requested from the other end,
so
.B no
will be largely ineffective unless both ends agree on it. Also see
.BR reauth .
.TP
.BR rekeyfuzz " = " 100% " | <percentage>"
maximum percentage by which
.BR marginbytes ,
.B marginpackets
and
.B margintime
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 `%'
(defaults to
.BR 100% ).
The value of
.BR marginTYPE ,
after this random increase,
must not exceed
.B lifeTYPE
(where TYPE is one of
.IR bytes ,
.I packets
or
.IR time ).
The value
.B 0%
will suppress randomization.
Relevant only locally, other end need not agree on it. Also see EXPIRY/REKEY
below.
.TP
.B rekeymargin
synonym for
.BR margintime .
.TP
.BR replay_window " = " \-1 " | <number>"
The IPsec replay window size for this connection. With the default of \-1
the value configured with
.I charon.replay_window
in
.BR strongswan.conf (5)
is used. Larger values than 32 are supported using the Netlink backend only,
a value of 0 disables IPsec replay protection.
.TP
.BR reqid " = <number>"
sets the reqid for a given connection to a pre-configured fixed value.
.TP
.BR sha256_96 " = " no " | yes"
HMAC-SHA-256 is used with 128-bit truncation with IPsec. For compatibility
with implementations that incorrectly use 96-bit truncation this option may be
enabled to configure the shorter truncation length in the kernel.  This is not
negotiated, so this only works with peers that use the incorrect truncation
length (or have this option enabled).
.TP
.BR tfc " = <value>"
number of bytes to pad ESP payload data to. Traffic Flow Confidentiality
is currently supported in IKEv2 and applies to outgoing packets only. The
special value
.BR %mtu
fills up ESP packets with padding to have the size of the MTU.
.TP
.BR type " = " tunnel " | transport | transport_proxy | passthrough | drop"
the type of the connection; currently the accepted values
are
.B tunnel
(the default)
signifying a host-to-host, host-to-subnet, or subnet-to-subnet tunnel;
.BR transport ,
signifying host-to-host transport mode;
.BR transport_proxy ,
signifying the special Mobile IPv6 transport proxy mode;
.BR passthrough ,
signifying that no IPsec processing should be done at all;
.BR drop ,
signifying that packets should be discarded.
.TP
.BR xauth " = " client " | server"
specifies the role in the XAuth protocol if activated by
.B authby=xauthpsk
or
.B authby=xauthrsasig.
Accepted values are
.B server
and
.B client
(the default).
.TP
.BR xauth_identity " = <id>"
defines the identity/username the client uses to reply to an XAuth request.
If not defined, the IKEv1 identity will be used as XAuth identity.

.SS "CONN PARAMETERS: IKEv2 MEDIATION EXTENSION"
The following parameters are relevant to IKEv2 Mediation Extension
operation only.
.TP
.BR mediation " = yes | " no
whether this connection is a mediation connection, ie. whether this
connection is used to mediate other connections.  Mediation connections
create no child SA. Acceptable values are
.B no
(the default) and
.BR yes .
.TP
.BR mediated_by " = <name>"
the name of the connection to mediate this connection through.  If given,
the connection will be mediated through the named mediation connection.
The mediation connection must set
.BR mediation=yes .
.TP
.BR me_peerid " = <id>"
ID as which the peer is known to the mediation server, ie. which the other
end of this connection uses as its
.B leftid
on its connection to the mediation server.  This is the ID we request the
mediation server to mediate us with.  If
.B me_peerid
is not given, the
.B rightid
of this connection will be used as peer ID.

.SH "CA SECTIONS"
These are optional sections that can be used to assign special
parameters to a Certification Authority (CA). Because the daemons
automatically import CA certificates from \fI/etc/ipsec.d/cacerts\fP,
there is no need to explicitly add them with a CA section, unless you
want to assign special parameters (like a CRL) to a CA.
.TP
.BR also " = <name>"
includes ca section
.BR <name> .
.TP
.BR auto " = " ignore " | add"
currently can have either the value
.B ignore
(the default) or
.BR add .
.TP
.BR cacert " = <path>"
defines a path to the CA certificate either relative to
\fI/etc/ipsec.d/cacerts\fP or as an absolute path.
.br
A value in the form
.B %smartcard[<slot nr>[@<module>]]:<keyid>
defines a specific CA certificate to load from a PKCS#11 backend for this CA.
See ipsec.secrets(5) for details about smartcard definitions.
.TP
.BR crluri " = <uri>"
defines a CRL distribution point (ldap, http, or file URI)
.TP
.B crluri1
synonym for
.B crluri.
.TP
.BR crluri2 " = <uri>"
defines an alternative CRL distribution point (ldap, http, or file URI)
.TP
.TP
.BR ocspuri " = <uri>"
defines an OCSP URI.
.TP
.B ocspuri1
synonym for
.B ocspuri.
.TP
.BR ocspuri2 " = <uri>"
defines an alternative OCSP URI.
.TP
.BR certuribase " = <uri>"
defines the base URI for the Hash and URL feature supported by IKEv2.
Instead of exchanging complete certificates, IKEv2 allows one to send an URI
that resolves to the DER encoded certificate. The certificate URIs are built
by appending the SHA1 hash of the DER encoded certificates to this base URI.
.SH "CONFIG SECTIONS"
At present, the only
.B config
section known to the IPsec software is the one named
.BR setup ,
which contains information used when the software is being started.
The currently-accepted
.I parameter
names in a
.B config
.B setup
section are:
.TP
.BR cachecrls " = yes | " no
if enabled, certificate revocation lists (CRLs) fetched via HTTP or LDAP will
be cached in
.I /etc/ipsec.d/crls/
under a unique file name derived from the certification authority's public key.
.TP
.BR charondebug " = <debug list>"
how much charon debugging output should be logged.
A comma separated list containing type/level-pairs may
be specified, e.g:
.B dmn 3, ike 1, net -1.
Acceptable values for types are
.B dmn, mgr, ike, chd, job, cfg, knl, net, asn, enc, lib, esp, tls,
.B tnc, imc, imv, pts
and the level is one of
.B -1, 0, 1, 2, 3, 4
(for silent, audit, control, controlmore, raw, private).  By default, the level
is set to
.B 1
for all types.  For more flexibility see LOGGER CONFIGURATION in
.IR strongswan.conf (5).
.TP
.BR strictcrlpolicy " = yes | ifuri | " no
defines if a fresh CRL must be available in order for the peer authentication
based on RSA signatures to succeed.
IKEv2 additionally recognizes
.B ifuri
which reverts to
.B yes
if at least one CRL URI is defined and to
.B no
if no URI is known.
.TP
.BR uniqueids " = " yes " | no | never | replace | keep"
whether a particular participant ID should be kept unique,
with any new IKE_SA using an ID deemed to replace all old ones using that ID;
acceptable values are
.B yes
(the default),
.B no
and
.BR never .
Participant IDs normally \fIare\fR unique, so a new IKE_SA using the same ID is
almost invariably intended to replace an old one. The difference between
.B no
and
.B never
is that the daemon will replace old IKE_SAs when receiving an INITIAL_CONTACT
notify if the option is
.B no
but will ignore these notifies if
.B never
is configured.
The daemon also accepts the value
.B replace
which is identical to
.B yes
and the value
.B keep
to reject new IKE_SA setups and keep the duplicate established earlier.

.SH IDENTITY PARSING
The type and binary encoding of identity strings specified in \fIleftid\fR
are detected as follows:
.IP \[bu]
If the string value contains an equal sign (=) it is assumed to be a
Distinguished Name, with RDNs separated by commas (,) \fIor\fR slashes (/ - the string
must start with a slash to use this syntax). An attempt is made to create a
binary ASN.1 encoding from this string. If that fails the type is set to KEY_ID
with the literal string value adopted as encoding.
.IP \[bu]
If the string value contains an @ the type depends on the position of that
character:
.RS
.IP \[bu]
If the string begins with @# the type is set to KEY_ID and the string following
that prefix is assumed to be the hex-encoded binary value of the identity.
.IP \[bu]
If the string begins with @@ the type is set to USER_FQDN and the encoding is
the literal string after that prefix.
.IP \[bu]
If the string begins with @ the type is set to FQDN and the encoding is the
literal string after that prefix.
.IP \[bu]
All remaining strings containing an @ are assumed to be of type USER_FQDN/RFC822
with the literal string value as encoding.
.RE
.IP \[bu]
If the value does not contain any @ or = characters it is parsed as follows:
.RS
.IP \[bu]
If the value is an empty string, or equals %any[6], 0.0.0.0, ::, or * the
type is set to ID_ANY, which matches any other identity.
.IP \[bu]
If the value contains a colon (:) it is assumed to be an IPv6 address. But if
parsing the address and converting it to its binary encoding fails the type is
set to KEY_ID and the encoding is the literal value.
.IP \[bu]
For all other strings an attempt at parsing them as IPv4 addresses is made. If
that fails the type is set to FQDN and the literal value is adopted as
encoding (this is where domain names and simple names end up).
.RE

.SH SA EXPIRY/REKEY
The IKE SAs and IPsec SAs negotiated by the daemon can be configured to expire
after a specific amount of time. For IPsec SAs this can also happen after a
specified number of transmitted packets or transmitted bytes. The following
settings can be used to configure this:
.TS
l r l r,- - - -,lB s lB s,a r a r.
Setting	Default	Setting	Default
IKE SA	IPsec SA
ikelifetime	3h	lifebytes	-
		lifepackets	-
		lifetime	1h
.TE
.SS Rekeying
IKE SAs as well as IPsec SAs can be rekeyed before they expire. This can be
configured using the following settings:
.TS
l r l r,- - - -,lB s lB s,a r a r.
Setting	Default	Setting	Default
IKE and IPsec SA	IPsec SA
margintime	9m	marginbytes	-
		marginpackets	-
.TE
.SS Randomization
To avoid collisions the specified margins are increased randomly before
subtracting them from the expiration limits (see formula below). This is
controlled by the
.B rekeyfuzz
setting:
.TS
l r,- -,lB s,a r.
Setting	Default
IKE and IPsec SA
rekeyfuzz	100%
.TE
.PP
Randomization can be disabled by setting
.BR rekeyfuzz " to " 0% .
.SS Formula
The following formula is used to calculate the rekey time of IPsec SAs:
.PP
.EX
 rekeytime = lifetime - (margintime + random(0, margintime * rekeyfuzz))
.EE
.PP
It applies equally to IKE SAs and byte and packet limits for IPsec SAs.
.SS Example
Let's consider the default configuration:
.PP
.EX
	lifetime = 1h
	margintime = 9m
	rekeyfuzz = 100%
.EE
.PP
From the formula above follows that the rekey time lies between:
.PP
.EX
	rekeytime_min = 1h - (9m + 9m) = 42m
	rekeytime_max = 1h - (9m + 0m) = 51m
.EE
.PP
Thus, the daemon will attempt to rekey the IPsec SA at a random time
between 42 and 51 minutes after establishing the SA. Or, in other words,
between 9 and 18 minutes before the SA expires.
.SS Notes
.IP \[bu]
Since the rekeying of an SA needs some time, the margin values must not be
too low.
.IP \[bu]
The value
.B margin... + margin... * rekeyfuzz
must not exceed the original limit. For example, specifying
.B margintime = 30m
in the default configuration is a bad idea as there is a chance that the rekey
time equals zero and, thus, rekeying gets disabled.

.SH FILES
.nf
/etc/ipsec.conf
/etc/ipsec.d/aacerts
/etc/ipsec.d/acerts
/etc/ipsec.d/cacerts
/etc/ipsec.d/certs
/etc/ipsec.d/crls

.SH SEE ALSO
strongswan.conf(5), ipsec.secrets(5), ipsec(8)
.SH HISTORY
Originally written for the FreeS/WAN project by Henry Spencer.
Updated and extended for the strongSwan project <http://www.strongswan.org> by
Tobias Brunner, Andreas Steffen and Martin Willi.