Merge branch 'ikev1'

[thirdparty/strongswan.git] / man / ipsec.conf.5.in

.TH IPSEC.CONF 5 "2011-12-14" "@IPSEC_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,
preceded and followed by empty lines.
If the file name is not a full pathname,
it is considered to be relative to the directory containing the
including file.
Such inclusions can be nested.
Only a single filename may be supplied, and it may not contain white space,
but it may include shell wildcards (see
.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.
Names must start with a letter and may contain only
letters, digits, periods, underscores, and hyphens.
All subsequent non-empty lines
which begin with white space are part of the section;
comments within a section must begin with white space too.
There may be only one section of a given type with a given name.
.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 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.
.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.
A
.I value
may contain white space only if the entire
.I value
is enclosed in double quotes (\fB"\fR);
a
.I value
cannot itself contain a double quote,
nor may it be continued across more than one line.
.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 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
.B also
in a single section,
although it is forbidden to append the same section more than once.)
.PP
A section with name
.B %default
specifies defaults for sections of the same type.
For each parameter in it,
any section of that type which does not have a parameter of the same name
gets a copy of the one from the
.B %default
section.
There may be multiple
.B %default
sections of a given type,
but only one default may be supplied for any specific parameter name,
and all
.B %default
sections of a given type must precede all non-\c
.B %default
sections of that type.
.B %default
sections may not contain the
.B also
parameter.
.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 also " = <name>"
includes conn section
.BR <name> .
.TP
.BR authby " = " pubkey " | rsasig | ecdsasig | psk | 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
.B rightsubnet
, a connection is established.
.B start
loads a connection and brings it up immediately.
.B ignore
ignores the connection. This is equal to delete a connection from the config
file.
Relevant only locally, other end need not agree on it
(but in general, for an intended-to-be-permanent connection,
both ends should use
.B auto=start
to ensure that any reboot causes immediate renegotiation).
.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 IPsec to propose both compressed and uncompressed,
and prefer compressed.
A value of
.B no
prevents IPsec from proposing compression;
a proposal to compress will still be accepted. IPComp is currently not supported
with IKEv1.
.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. If no activity is detected, all connections with a dead peer
are stopped and unrouted
.RB ( clear ),
put in the hold state
.RB ( hold )
or restarted
.RB ( restart ).
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 closeaction " = " none " | clear | hold | restart"
defines the action to take if the remote peer unexpectedly closes a CHILD_SA.
A closeaction should not be
used if the peer uses reauthentication or uniquids checking, as these events
might trigger a closeaction when not desired. Closeactions are currently
not supported with IKEv1.
.TP
.BR inactivity " = <time>"
defines the timeout interval, after which a CHILD_SA is closed if it did
not send or receive any traffic.
.TP
.BR eap_identity " = <id>"
defines the identity the client uses to reply to a 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] .
.br
Defaults to
.BR aes128-sha1,3des-sha1 .
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
.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: aes256-sha512-modp4096!
.br
If
.B dh-group
is specified, CHILD_SA/Quick Mode setup and rekeying include a separate
Diffie-Hellman exchange.  Valid values for
.B esnmode
(IKEv2 only) 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 ike " = <cipher suites>"
comma-separated list of IKE/ISAKMP SA encryption/authentication algorithms
to be used, e.g.
.BR aes128-sha1-modp2048 .
The notation is
.BR encryption-integrity-dhgroup .
In IKEv2, multiple algorithms and proposals may be included, such as
aes128-aes256-sha1-modp1536-modp2048,3des-sha1-md5-modp1024.
.br
Defaults to
.B aes128-sha1-modp2048,3des-sha1-modp1536 .
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
.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
.BR ( ! ,
exclamation mark) can be used, e.g: aes256-sha512-modp4096!
.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"
method of key exchange;
which protocol should be used to initialize 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> | %defaultroute | " %any
(required)
the IP address of the left participant's public-network interface
or one of several magic values.
If it is
.BR %defaultroute ,
.B left
will be filled in automatically with the local address
of the default-route interface (as determined at IPsec startup time and
during configuration update).
Either
.B left
or
.B right
may be
.BR %defaultroute ,
but not both.

The value
.B %any
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.
.br

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

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 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 strength in bits (for example
.BR rsa-2048
or
.BR ecdsa-256 ).
For
.B eap,
an optional EAP method can be appended. Currently defined methods are
.BR eap-aka ,
.BR eap-sim ,
.BR eap-gtc ,
.BR eap-md5 ,
.BR eap-mschapv2 ,
.BR eap-peap ,
.BR eap-sim ,
.BR eap-tls ,
.BR eap-ttls ,
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 ).
For
.B xauth,
a XAuth authentication backend can be specified, such as
.B xauth-generic
or
.B 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 RFC4739. 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.
.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 and
.B leftca
to the distinguished name of the certificate's issuer.
The left participant's ID can be overridden by specifying a
.B leftid
value which must be certified by the certificate, though.
.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 peers certificate must have.
OIDs are specified using the numerical dotted representation (IKEv2 only).
.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 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
.BR left .
Can be an IP address or a fully-qualified domain name preceded by
.B @
(which is used as a literal string and not resolved).
.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 to this port.
.TP
.BR leftnexthop " = %direct | %defaultroute | <ip address> | <fqdn>"
this parameter is usually not needed any more because the NETKEY IPsec stack
does not require explicit routing entries for the traffic to be tunneled. If
.B leftsourceip
is used with IKEv1 then
.B leftnexthop
must still be set in order for the source routes to work properly.
.TP
.BR leftprotoport " = <protocol>/<port>"
restrict the traffic selector to a single protocol and/or port.
Examples:
.B leftprotoport=tcp/http
or
.B leftprotoport=6/80
or
.B leftprotoport=udp
.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 " = %config | %cfg | %modeconfig | %modecfg | <ip address>"
The internal source IP 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 is requested from the peer.
.TP
.BR rightsourceip " = %config | <network>/<netmask> | %poolname"
The internal source IP 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
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>"
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 subnet 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.
.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.
.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 in charon, hence this parameter has no
effect.
.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.
.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 reqid " = <number>"
sets the reqid for a given connection to a pre-configured fixed value.
.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.
.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 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 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 | replace | keep"
whether a particular participant ID should be kept unique,
with any new (automatically keyed)
connection using an ID from a different IP address
deemed to replace all old ones using that ID;
acceptable values are
.B yes
(the default)
and
.BR no .
Participant IDs normally \fIare\fR unique,
so a new (automatically-keyed) connection using the same ID is
almost invariably intended to replace an old one.
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.
.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, tls, 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).

.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.
.SH BUGS
.PP
If conns are to be added before DNS is available, \fBleft=\fP\fIFQDN\fP
will fail.