Ubuntu Manpage: ipsec.conf - IPsec configuration and connections

Provided by: strongswan-starter_5.1.2-0ubuntu2.11_amd64

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 previously used
two separate keying daemons, pluto and charon. This manual does not discuss pluto options anymore, but
only charon that since strongSwan 5.0 supports both IKEv1 and IKEv2.

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.

aggressive = yes | no
whether to use IKEv1 Aggressive or Main Mode (the default).

ah = <cipher suites>
comma-separated list of AH algorithms to be used for the connection, e.g. sha1-sha256-modp1024.
The notation is 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 ah or esp keyword may be used, AH+ESP bundles are not supported.

There is no default, 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 (!) can be
added at the end.

If dh-group is specified, CHILD_SA/Quick Mode setup and rekeying include a separate Diffie-Hellman
exchange.

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

auth = <value>
was used by the pluto IKEv1 daemon to use AH integrity protection for ESP encrypted packets, but
is not supported in charon. The ah keyword specifies algorithms to use for integrity protection
with AH, but without encryption. AH+ESP bundles are not supported.

authby = pubkey | rsasig | ecdsasig | psk | secret | never | xauthpsk | xauthrsasig
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. This parameter is
deprecated, as two peers do not need to agree on an authentication method in IKEv2. Use the
leftauth parameter instead to define authentication methods.

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 deleting a connection from the config file.
Relevant only locally, other end need not agree on it.

closeaction = none | clear | hold | restart
defines the action to take if the remote peer unexpectedly closes a CHILD_SA (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 the defined action when not desired.

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 the daemon to propose both
compressed and uncompressed, and prefer compressed. A value of no prevents the daemon from
proposing or accepting compression.

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). The default is none which disables the active
sending of DPD messages.

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.

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.

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 %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][-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 ah or esp keyword may be used,
AH+ESP bundles are not supported.

Defaults to 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 (!) can
be added at the end.

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 (!,
exclamation mark) can be used, e.g: aes256-sha512-modp4096!
If dh-group is specified, CHILD_SA/Quick Mode setup and rekeying include a separate Diffie-Hellman
exchange. Valid values for esnmode (IKEv2 only) are esn and noesn. Specifying both negotiates
Extended Sequence Number support with the peer, the default 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.

fragmentation = yes | force | no
whether to use IKE fragmentation (proprietary IKEv1 extension). Acceptable values are yes, force
and no (the default). Fragmented messages sent by a peer are always accepted irrespective of the
value of this option. If set to yes, and the peer supports it, larger IKE messages will be sent in
fragments. If set to force the initial IKE message will already be fragmented if required.

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[-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 prf prefix (such as prfsha1, prfsha256 or prfaesxcbc).
In IKEv2, multiple algorithms and proposals may be included, such as
aes128-aes256-sha1-modp1536-modp2048,3des-sha1-md5-modp1024.

Defaults to 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 (!) can be added at the end.

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.

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 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
which key exchange protocol should be used to initiate the connection. Connections marked with
ike use IKEv2 when initiating, but accept any protocol version when responding.

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> | %any | <range> | <subnet>
The IP address of the left participant's public-network interface or one of several magic values.
The value %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 % in front of a fully-qualified domain name or an IP address will implicitly set
leftallowany=yes.

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

To limit the connection to a specific range of hosts, a range ( 10.1.0.0-10.2.255.255 ) or a
subnet ( 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.

leftallowany = yes | no
a modifier for left, making it behave as %any although a concrete IP address or domain name has
been assigned.

leftauth = <auth method>
Authentication method to use locally (left) or require from the remote (right) side. Acceptable
values are pubkey for public key authentication (RSA/ECDSA), psk for pre-shared key
authentication, eap to (require the) use of the Extensible Authentication Protocol in IKEv2, and
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 ecdsa-384
or rsa-2048-ecdsa-256). To limit the acceptable set of hashing algorithms for trustchain
validation, append hash algorithms to pubkey or a key strength definition (for example pubkey-
sha1-sha256 or rsa-2048-ecdsa-256-sha256-sha384-sha512). For eap, an optional EAP method can be
appended. Currently defined methods are eap-aka, eap-gtc, eap-md5, eap-mschapv2, eap-peap, eap-
sim, eap-tls, eap-ttls, eap-dynamic, and eap-radius. 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). For xauth, an XAuth authentication backend can be specified, such as xauth-generic
or xauth-eap. If XAuth is used in leftauth, Hybrid authentication is used. For traditional XAuth
authentication, define XAuth in lefauth2.

leftauth2 = <auth method>
Same as 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.

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. %same means that
the value configured for the right participant should be reused.

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. The left participant's ID can be overridden by specifying a leftid value
which must be certified by the certificate, though.
A value in the form %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. leftcert is required only if selecting the certificate with leftid is not
sufficient, for example if multiple certificates use the same subject.
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.

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

leftcertpolicy = <OIDs>
Comma separated list of certificate policy OIDs the peer's certificate must have. OIDs are
specified using the numerical dotted representation.

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 %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.

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.

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.

leftgroups2 = <group list>
Same as leftgroups, but for the second authentication round defined with leftauth2.

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 or the subject
of the certificate configured with leftcert. Can be an IP address, a fully-qualified domain name,
an email address, or a keyid. If leftcert is configured the identity has to be confirmed by the
certificate.

For IKEv2 and rightid the prefix % 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 leftid.

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. 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.

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 leftsubnet.

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 dns: or 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 or DER encoding.

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 = %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 %config, %cfg, %modeconfig, or %modecfg, an address (from the tunnel
address family) is requested from the peer. With %config4 and %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.

rightsourceip = %config | <network>/<netmask> | %poolname
Comma separated list of internal source IPs 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>[[<proto/port>]][,...]
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. 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.

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

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

If the protocol is icmp or 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 %opaque for RFC 4301 OPAQUE selectors, or a
numerical range in the form 1024-65535. None of the kernel backends currently supports opaque or
port ranges and uses %any for policy installation instead.

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

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. 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.

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

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

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.

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

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 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). Push mode is currently not supported with IKEv2.

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 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. Also see reauth.

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.

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).

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.

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.
              A  value in the form %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.

       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)

       ocspuri = <uri>
              defines an OCSP URI.

       ocspuri1
              synonym for ocspuri.

       ocspuri2 = <uri>
              defines an alternative OCSP URI.

       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.

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. The currently-accepted parameter names in a config
setup section are:

cachecrls = yes | no
if enabled, 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.

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, asn, enc, lib, esp, tls, tnc, imc, imv, pts and the level is one of -1,
0, 1, 2, 3, 4 (for silent, audit, control, controlmore, raw, private). By default, the level is
set to 1 for all types. For more flexibility see LOGGER CONFIGURATION in strongswan.conf(5).

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 | 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 yes (the default), no and never.
Participant IDs normally are unique, so a new IKE_SA using the same ID is almost invariably
intended to replace an old one. The difference between no and never is that the daemon will
replace old IKE_SAs when receiving an INITIAL_CONTACT notify if the option is no but will ignore
these notifies if never is configured. The 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.

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:
       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

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.

5.1.2                                              2012-06-26                                      IPSEC.CONF(5)