IPSEC.CONF(5)

NAME
ipsec.conf - IPsec configuration and connections

DESCRIPTION
The optional ipsec.conf file specifies most configuration and control information for the strongSwan IPsec subsystem. The major exception is secrets for authentication; see ipsec.secrets(5). Its contents are not security-sensitive.

The file is a text file, consisting of one or more sections. White space followed by # followed by anything to the end of the line is a comment and is ignored, as are empty lines which are not within a section.

A line which contains include and a file name, separated by white space, is replaced by the contents of that file, preceded and followed by empty lines. If the file name is not a full pathname, it is considered to be relative to the directory containing the including file. Such inclusions can be nested. Only a single filename may be supplied, and it may not contain white space, but it may include shell wildcards (see sh(1)); for example:

include ipsec.*.conf

The intention of the include facility is mostly to permit keeping information on connections, or sets of connections, separate from the main configuration file. This permits such connection descriptions to be changed, copied to the other security gateways involved, etc., without having to constantly extract them from the configuration file and then insert them back into it. Note also the also parameter (described below) which permits splitting a single logical section (e.g. a connection description) into several actual sections.

A section begins with a line of the form:

type name

where type indicates what type of section follows, and name is an arbitrary name which distinguishes the section from others of the same type. Names must start with a letter and may contain only letters, digits, periods, underscores, and hyphens. All subsequent non-empty lines which begin with white space are part of the section; comments within a section must begin with white space too. There may be only one section of a given type with a given name.

Lines within the section are generally of the form

parameter=value

(note the mandatory preceding white space). There can be white space on either side of the =. Parameter names follow the same syntax as section names, and are specific to a section type. Unless otherwise explicitly specified, no parameter name may appear more than once in a section.

An empty value stands for the system default value (if any) of the parameter, i.e. it is roughly equivalent to omitting the parameter line entirely. A value may contain white space only if the entire value is enclosed in double quotes ("); a value cannot itself contain a double quote, nor may it be continued across more than one line.

Numeric values are specified to be either an ``integer'' (a sequence of digits) or a ``decimal number'' (sequence of digits optionally followed by `.' and another sequence of digits).

There is currently one parameter which is available in any type of section:

also
    the value is a section name; the parameters of that section are appended to this section, as if they had been written as part of it. The specified section must exist, must follow the current one, and must have the same section type. (Nesting is permitted, and there may be more than one also in a single section, although it is forbidden to append the same section more than once.)

A section with name %default specifies defaults for sections of the same type. For each parameter in it, any section of that type which does not have a parameter of the same name gets a copy of the one from the %default section. There may be multiple %default sections of a given type, but only one default may be supplied for any specific parameter name, and all %default sections of a given type must precede all non-%default sections of that type. %default sections may not contain the also parameter.

Currently there are three types of sections: a config section specifies general configuration information for IPsec, a conn section specifies an IPsec connection, while a ca section specifies special properties of a certification authority.

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. Here's a simple example:

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

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 currently uses two separate keying daemons. pluto handles all IKEv1 connections, charon is the daemon handling the IKEv2 protocol.

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; for every connection description an attempt is made to figure out whether the local endpoint should act as the left or 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, 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 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
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.

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.

also = <name>
    includes conn section <name>.

auth = esp | ah
    whether authentication should be done as part of ESP encryption, or separately using the AH protocol; acceptable values are esp (the default) and ah.
    The IKEv2 daemon currently supports ESP only.

authby = pubkey | rsasig | ecdsasig | psk | eap | never | xauth...
    how the two security gateways should authenticate each other; acceptable values are psk or secret for pre-shared secrets, pubkey (the default) for public key signatures as well as the synonyms rsasig for RSA digital signatures and ecdsasig for Elliptic Curve DSA signatures. 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 xauthpsk and xauthrsasig that will enable eXtended AUTHentication (XAUTH) in addition to IKEv1 main mode based on shared secrets or digital RSA signatures, respectively. IKEv2 additionally supports the value eap, which indicates an initiator to request EAP authentication. The EAP method to use is selected by the server (see eap). This parameter is deprecated for IKEv2 connections, as two peers do not need to agree on an authentication method. Use the leftauth parameter instead to define authentication methods in IKEv2.

auto = ignore | add | route | start
    what operation, if any, should be done automatically at IPsec startup; currently-accepted values are add, route, start and ignore (the default). add loads a connection without starting it. route loads a connection and installs kernel traps. If traffic is detected between leftsubnet and rightsubnet , a connection is established. start loads a connection and brings it up immediately. 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 auto=start to ensure that any reboot causes immediate renegotiation).

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 before encryption); acceptable values are yes and no (the default). A value of yes causes IPsec to propose both compressed and uncompressed, and prefer compressed. A value of no prevents IPsec from proposing compression; a proposal to compress will still be accepted.

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 clear, hold, and restart all activate DPD. If no activity is detected, all connections with a dead peer are stopped and unrouted (clear), put in the hold state (hold) or restarted (restart). For IKEv1, the default is none which disables the active sending of R_U_THERE notifications. Nevertheless pluto will always send the DPD Vendor ID during connection set up in order to signal the readiness to act passively as a responder if the peer wants to use DPD. For IKEv2, none does't make sense, since all messages are used to detect dead peers. If specified, it has the same meaning as the default (clear).

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.

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. See strongswan.conf(5) for a description of the IKEv2 retransmission timeout.

closeaction = none | clear | hold | restart
    defines the action to take if the remote peer unexpectedly closes a CHILD_SA (IKEv2 only, see dpdaction for meaning of values). A closeaction should not be used if the peer uses reauthentication or uniquids checking, as these events might trigger a closeaction when not desired.

inactivity = <time>
    defines the timeout interval, after which a CHILD_SA is closed if it did not send or receive any traffic. Currently supported in IKEv2 connections only.

eap = md5 | mschapv2 | radius | ... | <type> | <type>-<vendor>
    defines the EAP type to propose as server if the client requests EAP authentication. Currently supported values are aka for EAP-AKA, gtc for EAP-GTC, md5 for EAP-MD5, mschapv2 for EAP-MS-CHAPv2, radius for the EAP-RADIUS proxy and sim for EAP-SIM. Additionally, IANA assigned EAP method numbers are accepted, or a definition in the form eap=type-vendor (e.g. eap=7-12345) can be used to specify vendor specific EAP types. This parameter is deprecated in the favour of leftauth. To forward EAP authentication to a RADIUS server using the EAP-RADIUS plugin, set eap=radius.

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 %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.

esp = <cipher suites>
    comma-separated list of ESP encryption/authentication algorithms to be used for the connection, e.g. aes128-sha256. The notation is encryption-integrity[-dhgroup][-esnmodes].
    If dh-group is specified, CHILD_SA setup and rekeying include a separate diffe hellman exchange (IKEv2 only). Valid esnmodes (IKEv2 only) are esn and noesn. Specifying both negotiates Extended Sequence number support with the peer, the defaut is noesn.

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 (IKEv2 only).

ike = <cipher suites>
    comma-separated list of IKE/ISAKMP SA encryption/authentication algorithms to be used, e.g. aes128-sha1-modp2048. The notation is encryption-integrity-dhgroup. In IKEv2, multiple algorithms and proposals may be included, such as aes128-aes256-sha1-modp1536-modp2048,3des-sha1-md5-modp1024.

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.

installpolicy = yes | no
    decides whether IPsec policies are installed in the kernel by the IKEv2 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 yes (the default) and no.

keyexchange = ike | ikev1 | ikev2
    method of key exchange; which protocol should be used to initialize the connection. Connections marked with ikev1 are initiated with pluto, those marked with ikev2 with charon. An incoming request from the remote peer is handled by the correct daemon, unaffected from the keyexchange setting. Starting with strongSwan 4.5 the default value ike is a synonym for ikev2, whereas in older strongSwan releases ikev1 was assumed.

keyingtries = 3 | <number> | %forever
    how many attempts (a whole number or %forever) should be made to negotiate a connection, or a replacement for one, before giving up (default 3). The value %forever means 'never give up'. Relevant only locally, other end need not agree on it.

keylife
    synonym for lifetime.

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 %defaultroute, 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 left or right may be %defaultroute, but not both. The prefix % in front of a fully-qualified domain name or an IP address will implicitly set leftallowany=yes. If the domain name cannot be resolved into an IP address at IPsec startup or update time then left=%any and leftallowany=no will be assumed. In case of an IKEv2 connection, the value %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.
    Note that specifying %any for the local endpoint is not supported by the IKEv1 pluto daemon. If %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.

leftallowany = yes | no
    a modifier for left , making it behave as %any although a concrete IP address has been assigned. Recommended for dynamic IP addresses that can be resolved by DynDNS at IPsec startup or update time. Acceptable values are yes and no (the default).

leftauth = <auth method>
    Authentication method to use locally (left) or require from the remote (right) side. This parameter is supported in IKEv2 only. Acceptable values are pubkey for public key authentication (RSA/ECDSA), psk for pre-shared key authentication and eap to (require the) use of the Extensible Authentication Protocol. To require a trustchain public key strength for the remote side, specify the key type followed by the strength in bits (for example rsa-2048 or ecdsa-256). For eap, an optional EAP method can be appended. Currently defined methods are eap-aka, eap-gtc, eap-md5, eap-tls, eap-mschapv2 and eap-sim. Alternatively, IANA assigned EAP method numbers are accepted. Vendor specific EAP methods are defined in the form eap-type-vendor (e.g. eap-7-12345).

leftauth2 = <auth method>
    Same as leftauth, but defines an additional authentication exchange. IKEv2 supports multiple authentication rounds using "Multiple Authentication Exchanges" defined in RFC4739. This allows, for example, separated authentication of host and user (IKEv2 only).

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.

leftca2 = <issuer dn> | %same
    Same as leftca, but for the second authentication round (IKEv2 only).

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 /etc/ipsec.d/certs are accepted. By default leftcert sets leftid to the distinguished name of the certificate's subject and leftca to the distinguished name of the certificate's issuer. The left participant's ID can be overridden by specifying a leftid value which must be certified by the certificate, though.

leftcert2 = <path>
    Same as leftcert, but for the second authentication round (IKEv2 only).

leftcertpolicy = <OIDs>
    Comma separated list of certificate policy OIDs the peers certificate must have. OIDs are specified using the numerical dotted representation (IKEv2 only).

leftfirewall = yes | no
    whether the left participant is doing forwarding-firewalling (including masquerading) using iptables for traffic from leftsubnet, which should be turned off (for traffic to the other subnet) once the connection is established; acceptable values are yes and no (the default). May not be used in the same connection description with leftupdown. Implemented as a parameter to the default ipsec _updown 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 ipsec _updown script (see pluto(8)). 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.

leftgroups = <group list>
    a comma separated list of group names. If the leftgroups parameter is present then the peer must be a member of at least one of the groups defined by the parameter. Group membership must be certified by a valid attribute certificate stored in /etc/ipsec.d/acerts/ thas has been issued to the peer by a trusted Authorization Authority stored in /etc/ipsec.d/aacerts/.
    Attribute certificates are not supported in IKEv2 yet.

lefthostaccess = yes | no
    inserts a pair of INPUT and OUTPUT iptables rules using the default ipsec _updown 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 yes and no (the default).

leftid = <id>
    how the left participant should be identified for authentication; defaults to left. Can be an IP address or a fully-qualified domain name preceded by @ (which is used as a literal string and not resolved).

leftid2 = <id>
    identity to use for a second authentication for the left participant (IKEv2 only); defaults to leftid.

leftikeport = <port>
    UDP port the left participant uses for IKE communication. Currently supported in IKEv2 connections only. 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.

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 leftsourceip is used with IKEv1 then leftnexthop must still be set in order for the source routes to work properly.

leftprotoport = <protocol>/<port>
    restrict the traffic selector to a single protocol and/or port. Examples: leftprotoport=tcp/http or leftprotoport=6/80 or leftprotoport=udp

leftrsasigkey = %cert | <raw rsa public key>
    the left participant's public key for RSA signature authentication, in RFC 2537 format using ttodata(3) encoding. The magic value %none means the same as not specifying a value (useful to override a default). The value %cert (the default) means that the key is extracted from a certificate. The identity used for the left participant must be a specific host, not %any or another magic value. Caution: if two connection descriptions specify different public keys for the same leftid, confusion and madness will ensue.

leftsendcert = never | no | ifasked | always | yes
    Accepted values are never or no, always or yes, and ifasked (the default), the latter meaning that the peer must send a certificate request payload in order to get a certificate in return.

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 %config, %cfg, %modeconfig, or %modecfg, an address is requested from the peer. In IKEv2, a statically defined address is also requested, since the server may change it.

rightsourceip = %config | <network>/<netmask> | %poolname
    The internal source IP to use in a tunnel for the remote peer. If the value is %config on the responder side, the initiator must propose an address which is then echoed back. Also supported are address pools expressed as network/netmask or the use of an external IP address pool using %poolname, where poolname is the name of the IP address pool used for the lookup.

leftsubnet = <ip subnet>
    private subnet behind the left participant, expressed as network/netmask; if omitted, essentially assumed to be left/32, signifying that the left end of the connection goes to the left participant only. When using IKEv2, the configured subnet of the peers may differ, the protocol narrows it to the greatest common subnet. Further, IKEv2 supports multiple subnets separated by commas. IKEv1 only interprets the first subnet of such a definition.

leftsubnetwithin = <ip subnet>
    the peer can propose any subnet or single IP address that fits within the range defined by leftsubnetwithin. Not relevant for IKEv2, as subnets are narrowed.

leftupdown = <path>
    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. See pluto(8) for details. Relevant only locally, other end need not agree on it. IKEv2 uses the updown script to insert firewall rules only, since routing has been implemented directly into charon.

lifebytes = <number>
    the number of bytes transmitted over an IPsec SA before it expires (IKEv2 only).

lifepackets = <number>
    the number of packets transmitted over an IPsec SA before it expires (IKEv2 only).

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 s (a time in seconds) or a decimal number followed by m, h, or d (a time in minutes, hours, or days respectively) (default 1h, maximum 24h). Normally, the connection is renegotiated (via the keying channel) before it expires (see margintime). The two ends need not exactly agree on 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.

marginbytes = <number>
    how many bytes before IPsec SA expiry (see lifebytes) should attempts to negotiate a replacement begin (IKEv2 only).

marginpackets = <number>
    how many packets before IPsec SA expiry (see lifepackets) should attempts to negotiate a replacement begin (IKEv2 only).

margintime = 9m | <time>
    how long before connection expiry or keying-channel expiry should attempts to negotiate a replacement begin; acceptable values as for lifetime (default 9m). Relevant only locally, other end need not agree on it. Also see EXPIRY/REKEY below.

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 0xffffffff is assumed.

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 0xffffffff is assumed.

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 0xffffffff is assumed.

mobike = yes | no
    enables the IKEv2 MOBIKE protocol defined by RFC 4555. Accepted values are yes (the default) and no. If set to no, the IKEv2 charon daemon will not actively propose MOBIKE as initiator and ignore the MOBIKE_SUPPORTED notify as responder.

modeconfig = push | pull
    defines which mode is used to assign a virtual IP. Accepted values are push and pull (the default). Currently relevant for IKEv1 only since IKEv2 always uses the configuration payload in pull mode. Cisco VPN gateways usually operate in push mode.

pfs = yes | no
    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. IKEv2 always uses PFS for IKE_SA rekeying whereas for CHILD_SA rekeying PFS is enforced by defining a Diffie-Hellman modp group in the esp parameter.

pfsgroup = <modp group>
    defines a Diffie-Hellman group for perfect forward secrecy in IKEv1 Quick Mode differing from the DH group used for IKEv1 Main Mode (IKEv1 only).

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 no rekeys without uninstalling the IPsec SAs, a value of yes (the default) creates a new IKE_SA from scratch and tries to recreate all IPsec SAs.

rekey = yes | no
    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/charon 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.

rekeyfuzz = 100% | <percentage>
    maximum percentage by which marginbytes, marginpackets and 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 100%). The value of marginTYPE, after this random increase, must not exceed lifeTYPE (where TYPE is one of bytes, packets or time). The value 0% will suppress randomization. Relevant only locally, other end need not agree on it. Also see EXPIRY/REKEY below.

rekeymargin
    synonym for margintime.

reqid = <number>
    sets the reqid for a given connection to a pre-configured fixed value.

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 %mtu fills up ESP packets with padding to have the size of the MTU.

type = tunnel | transport | transport_proxy | passthrough | drop
    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; transport_proxy, signifying the special Mobile IPv6 transport proxy 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 (reject is currently not supported by the NETKEY stack of the Linux 2.6 kernel). The IKEv2 daemon charon currently supports tunnel, transport, and transport_proxy connection types, only.

xauth = client | server
    specifies the role in the XAUTH protocol if activated by authby=xauthpsk or authby=xauthrsasig. Accepted values are server and client (the default).

  CONN PARAMETERS: IKEv2 MEDIATION EXTENSION
The following parameters are relevant to IKEv2 Mediation Extension operation only.

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 no (the default) and yes.

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 mediation=yes.

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 leftid on its connection to the mediation server. This is the ID we request the mediation server to mediate us with. If me_peerid is not given, the rightid of this connection will be used as peer ID.

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 /etc/ipsec.d/cacerts, 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.

also = <name>
    includes ca section <name>.

auto = ignore | add
    currently can have either the value ignore (the default) or add.

cacert = <path>
    defines a path to the CA certificate either relative to /etc/ipsec.d/cacerts or as an absolute path.

crluri = <uri>
    defines a CRL distribution point (ldap, http, or file URI)

crluri1
    synonym for crluri.

crluri2 = <uri>
    defines an alternative CRL distribution point (ldap, http, or file URI)

ldaphost = <hostname>
    defines an ldap host. Currently used by IKEv1 only.

ocspuri = <uri>
    defines an OCSP URI.

ocspuri1
    synonym for ocspuri.

ocspuri2 = <uri>
    defines an alternative OCSP URI. Currently used by IKEv2 only.

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.

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. Here's an example:

config setup
	plutodebug=all
	crlcheckinterval=10m
	strictcrlpolicy=yes

Parameters are optional unless marked ``(required)''. The currently-accepted parameter names in a config setup section affecting both daemons are:

cachecrls = yes | no
    certificate revocation lists (CRLs) fetched via http or ldap will be cached in /etc/ipsec.d/crls/ under a unique file name derived from the certification authority's public key. Accepted values are yes and no (the default). Only relevant for IKEv1, as CRLs are always cached in IKEv2.

charonstart = yes | no
    whether to start the IKEv2 charon daemon or not. The default is yes if starter was compiled with IKEv2 support.

plutostart = yes | no
    whether to start the IKEv1 pluto daemon or not. The default is yes if starter was compiled with IKEv1 support.

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 ifuri which reverts to yes if at least one CRL URI is defined and to no if no URI is known.

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 yes (the default) and no. Participant IDs normally are unique, so a new (automatically-keyed) connection using the same ID is almost invariably intended to replace an old one. The IKEv2 daemon also accepts the value replace which is identical to yes and the value keep to reject new IKE_SA setups and keep the duplicate established earlier.

The following config section parameters are used by the IKEv1 Pluto daemon only:

crlcheckinterval = 0s | <time>
    interval in seconds. CRL fetching is enabled if the value is greater than zero. Asynchronous, periodic checking for fresh CRLs is currently done by the IKEv1 Pluto daemon only.

keep_alive = 20s | <time>
    interval in seconds between NAT keep alive packets, the default being 20 seconds.

nat_traversal = yes | no
    activates NAT traversal by accepting source ISAKMP ports different from udp/500 and being able of floating to udp/4500 if a NAT situation is detected. Accepted values are yes and no (the default). Used by IKEv1 only, NAT traversal is always being active in IKEv2.

nocrsend = yes | no
    no certificate request payloads will be sent.

pkcs11initargs = <args>
    non-standard argument string for PKCS#11 C_Initialize() function; required by NSS softoken.

pkcs11module = <args>
    defines the path to a dynamically loadable PKCS #11 library.

pkcs11keepstate = yes | no
    PKCS #11 login sessions will be kept during the whole lifetime of the keying daemon. Useful with pin-pad smart card readers. Accepted values are yes and no (the default).

pkcs11proxy = yes | no
    Pluto will act as a PKCS #11 proxy accessible via the whack interface. Accepted values are yes and no (the default).

plutodebug = none | <debug list> | all
    how much pluto debugging output should be logged. An empty value, or the magic value none, means no debugging output (the default). The magic value all means full output. Otherwise only the specified types of output (a quoted list, names without the --debug- prefix, separated by white space) are enabled; for details on available debugging types, see pluto(8).

plutostderrlog = <file>
    Pluto will not use syslog, but rather log to stderr, and redirect stderr to <file>.

postpluto = <command>
    shell command to run after starting pluto (e.g., to remove a decrypted copy of the ipsec.secrets file). It's run in a very simple way; complexities like I/O redirection are best hidden within a script. Any output is redirected for logging, so running interactive commands is difficult unless they use /dev/tty or equivalent for their interaction. Default is none.

prepluto = <command>
    shell command to run before starting pluto (e.g., to decrypt an encrypted copy of the ipsec.secrets file). It's run in a very simple way; complexities like I/O redirection are best hidden within a script. Any output is redirected for logging, so running interactive commands is difficult unless they use /dev/tty or equivalent for their interaction. Default is none.

virtual_private = <networks>
    defines private networks using a wildcard notation.

The following config section parameters are used by the IKEv2 charon daemon only:

charondebug = <debug list>
    how much charon debugging output should be logged. A comma separated list containing type level/pairs may be specified, e.g: dmn 3, ike 1, net -1. Acceptable values for types are dmn, mgr, ike, chd, job, cfg, knl, net, enc, lib and the level is one of -1, 0, 1, 2, 3, 4 (for silent, audit, control, controlmore, raw, private). For more flexibility see LOGGER CONFIGURATION in strongswan.conf(5).

IKEv2 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:
Setting | Default | Setting | Default
IKE SA | IPsec SA
ikelifetime | 3h | lifebytes | -
 |  | lifepackets | -
 |  | lifetime | 1h

  Rekeying
IKE SAs as well as IPsec SAs can be rekeyed before they expire. This can be configured using the following settings:
Setting | Default | Setting | Default
IKE and IPsec SA | IPsec SA
margintime | 9m | marginbytes | -
 |  | marginpackets | -

  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 rekeyfuzz setting:
Setting | Default
IKE and IPsec SA
rekeyfuzz | 100%

Randomization can be disabled by setting rekeyfuzz to 0%.

  Formula
The following formula is used to calculate the rekey time of IPsec SAs:

     rekeytime = lifetime - (margintime + random(0, margintime * rekeyfuzz))

It applies equally to IKE SAs and byte and packet limits for IPsec SAs.

  Example
Let's consider the default configuration:

    	lifetime = 1h
    	margintime = 9m
    	rekeyfuzz = 100%

From the formula above follows that the rekey time lies between:

    	rekeytime_min = 1h - (9m + 9m) = 42m
    	rekeytime_max = 1h - (9m + 0m) = 51m

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.

  Notes

•   Since the rekeying of an SA needs some time, the margin values must not be too low.

•   The value margin... + margin... * rekeyfuzz must not exceed the original limit. For example, specifying 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.

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

SEE ALSO
strongswan.conf(5), ipsec.secrets(5), ipsec(8), pluto(8)

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.

BUGS

If conns are to be added before DNS is available, left=FQDN will fail.