ipsec.conf - IPsec configuration and connections
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
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. 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:
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
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:
indicates what type of section follows, and name
arbitrary name which distinguishes the section from others of the same type.
All subsequent non-empty lines which begin with white space are part of the
section. Sections of the same type that share the same name are merged.
Lines within the section are generally of the form
(note the mandatory preceding white space). There can be white space on either
side of the =
. Parameter names are specific to a section type.
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. This may be useful to clear a setting inherited from a
section or via also
parameter (see below). A
may contain single spaces (additional white space is reduced to
one space). To preserve white space as written enclose the entire value
in double quotes ( "
); in such values double quotes themselves may
be escaped by prefixing them with \
characters. A double-quoted string
may span multiple lines by ending them with \
lines don't have to begin with white space, as that will be preserved).
Additionally, the following control characters may be encoded in double-quoted
strings: \n, \r, \t, \b, \f.
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:
- the value is a section name; the parameters of that section
are inherited by the current section. Parameters in the current section
always override inherited parameters, even if an also follows after
them. The specified section must exist and must have the same section
type; it doesn't if it is defined before or after the current section.
Nesting is permitted, and there may be more than one also in a
single section (parameters from referenced sections are inherited and
overridden in the order of these also parameters).
A section with name %default
specifies defaults for sections of the same
type. All parameters in it, are inherited by all other sections of that type.
Currently there are three types of sections: a config
general configuration information for IPsec, a conn
an IPsec connection, while a ca
section specifies special properties of
a certification authority.
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:
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
. This manual does not discuss pluto
options anymore, but
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
participants, rather than in terms of local and
remote. Which participant is considered left
arbitrary; for every connection description an attempt is made to figure out
whether the local endpoint should act as the left
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
the local side and right
for the remote side (the first letters are a
Many of the parameters relate to one participant or the other; only the ones for
are listed here, but every parameter whose name begins with
has a right
counterpart, whose description is the same but
Parameters are optional unless marked '(required)'.
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
- 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 AH cipher suite since by default ESP is used. The daemon
adds its extensive default proposal to the configured value. To restrict
it to the configured proposal an exclamation mark (!) can be added
at the end.
If dh-group is specified, CHILD_SA/Quick Mode setup and rekeying
include a separate Diffie-Hellman exchange (refer to the esp
keyword for details).
- 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
- 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 |
- 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
- 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 |
- 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 and determine the action to perform on a
timeout. With clear the connection is closed with no further
actions taken. hold installs a trap policy, which will catch
matching traffic and tries to re-negotiate the connection on demand.
restart will immediately trigger an attempt to re-negotiation the
connection. 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
- 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-sha256. The daemon adds its extensive default
proposal to this default or the configured value. To restrict it to the
configured proposal an exclamation mark (!) can be added at the
Note: As a responder, the daemon defaults to selecting the first
configured proposal that's also supported by the peer. This may be changed
via strongswan.conf(5) to selecting the first acceptable proposal
sent by the peer instead. In order to restrict a responder to only accept
specific cipher suites, the strict flag (!, exclamation mark) can
be used, e.g: aes256-sha512-modp4096!
If dh-group is specified, CHILD_SA/Quick Mode rekeying and initial
negotiation use a separate Diffie-Hellman exchange using the specified
group. However, for IKEv2, the keys of the CHILD_SA created implicitly
with the IKE_SA will always be derived from the IKE_SA's key material. So
any DH group specified here will only apply when the CHILD_SA is later
rekeyed or is created with a separate CREATE_CHILD_SA exchange. Therefore,
a proposal mismatch might not immediately be noticed when the SA is
established, but may later cause rekeying to fail.
Valid values for esnmode 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
- fragmentation = yes | accept | force |
- whether to use IKE fragmentation (proprietary IKEv1
extension or IKEv2 fragmentation as per RFC 7383). Acceptable values are
yes (the default), accept, force and no. If
set to yes, and the peer supports it, oversized IKE messages will
be sent in fragments. If set to accept, support for fragmentation
is announced to the peer but the daemon does not send its own messages in
fragments. If set to force (only supported for IKEv1) the initial
IKE message will already be fragmented if required. Finally, setting the
option to no will disable announcing support for this feature.
Note that fragmented IKE messages sent by a peer are always accepted
irrespective of the value of this option (even when set to
- ike = <cipher suites>
- comma-separated list of IKE/ISAKMP SA
encryption/authentication algorithms to be used, e.g.
aes128-sha256-modp3072. 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
Defaults to aes128-sha256-modp3072. The daemon adds its extensive
default proposal to this default or the configured value. To restrict it
to the configured proposal an exclamation mark (!) can be added at
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!
- 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
- 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
- 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> |
- 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.
- 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
If an FQDN is assigned it is resolved every time a configuration
lookup is done. If DNS resolution times out, the lookup is delayed for
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
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
rsa-2048-ecdsa-256-sha256-sha384-sha512). Unless disabled in
strongswan.conf(5), or explicit IKEv2 signature constraints are
configured (see below), such key types and hash algorithms are also
applied as constraints against IKEv2 signature authentication schemes used
by the remote side.
If both peers support RFC 7427 ("Signature Authentication in
IKEv2") specific hash algorithms to be used during IKEv2
authentication may be configured. The syntax is the same as above, but
with ike: prefix. For example, with ike:pubkey-sha384-sha256 a
public key signature scheme with either SHA-384 or SHA-256 would get used
for authentication, in that order and depending on the hash algorithms
supported by the peer. If no specific hash algorithms are configured, the
default is to prefer an algorithm that matches or exceeds the strength of
the signature key. If no constraints with ike: prefix are configured any
signature scheme constraint (without ike: prefix) will also apply to IKEv2
authentication, unless this is disabled in strongswan.conf(5).
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).
To specify signature and trust chain constraints for EAP-(T)TLS, append a
colon to the EAP method, followed by the key type/size and hash algorithm
as discussed above. For 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
- 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
- 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
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
- leftid = <id>
- how the left participant should be identified for
authentication; defaults to left or the subject of the certificate
configured with leftcert. If leftcert is configured the
identity has to be confirmed by the certificate.
Can be an IP address, a fully-qualified domain name, an email address or a
Distinguished Name for which the ID type is determined automatically and
the string is converted to the appropriate encoding. The rules for this
conversion are described in IDENTITY PARSING below.
In certain special situations the identity parsing above might be inadequate
or produce the wrong result. Examples are the need to encode a FQDN as
KEY_ID or the string parser being unable to produce the correct binary
ASN.1 encoding of a certificate's DN. For these situations it is possible
to enforce a specific identity type and to provide the binary encoding of
the identity. To do this a prefix may be used, followed by a colon (:). If
the number sign (#) follows the colon, the remaining data is interpreted
as hex encoding, otherwise the string is used as is as the identification
data. Note: The latter implies that no conversion is performed for
non-string identities. For example, ipv4:10.0.0.1 does not create a
valid ID_IPV4_ADDR IKE identity, as it does not get converted to binary
0x0a000001. Instead, one could use ipv4:#0a000001 to get a valid
identity, but just using the implicit type with automatic conversion is
usually simpler. The same applies to the ASN.1 encoded types. The
following prefixes are known: ipv4, ipv6, rfc822,
email, userfqdn, fqdn, dns, asn1dn,
asn1gn and keyid. Custom type prefixes may be specified by
surrounding the numerical type value by curly brackets.
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
- 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, DER or SSH encoding. Both absolute paths or paths relative to
/etc/ipsec.d/certs are accepted.
- leftsendcert = never | no | ifasked | always
- 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
- 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
- rightsourceip = %config |
<network>/<netmask> | <from>-<to> | %poolname
- Comma separated list of internal source IPs to use in a
tunnel for the remote peer. If the value is %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 and from-to or
the use of an external IP address pool using % poolname, where
poolname is the name of the IP address pool used for the
- leftsubnet = <ip
- 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. This is due to a limitation of the IKEv1 protocol, which only
allows a single pair of subnets per CHILD_SA. So to tunnel several subnets
a conn entry has to be defined and brought up for each pair of subnets.
The optional part after each subnet enclosed in square brackets specifies a
protocol/port to restrict the selector for that subnet.
Examples: 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.
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
- lifepackets = <number>
- the number of packets transmitted over an IPsec SA before
- 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. The special value %unique assigns a unique value to
each newly created IPsec SA. To additionally make the mark unique for each
IPsec SA direction (in/out) the special value %unique-dir may be
- 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
- 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
- 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. The setting must be the same on both
- 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
- 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
- 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.
- synonym for margintime.
- replay_window = -1 | <number>
- The IPsec replay window size for this connection. With the
default of -1 the value configured with charon.replay_window in
strongswan.conf(5) is used. Larger values than 32 are supported
using the Netlink backend only, a value of 0 disables IPsec replay
- reqid = <number>
- sets the reqid for a given connection to a pre-configured
- sha256_96 = no | yes
- HMAC-SHA-256 is used with 128-bit truncation with IPsec.
For compatibility with implementations that incorrectly use 96-bit
truncation this option may be enabled to configure the shorter truncation
length in the kernel. This is not negotiated, so this only works with
peers that use the incorrect truncation length (or have this option
- 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
The following parameters are relevant to IKEv2 Mediation Extension operation
- 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
- 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.
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
- synonym for crluri.
- crluri2 = <uri>
- defines an alternative CRL distribution point (ldap, http,
or file URI)
- ocspuri = <uri>
- defines an OCSP URI.
- 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.
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
- 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
- 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 |
- 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.
The type and binary encoding of identity strings specified in leftid
detected as follows:
- If the string value contains an equal sign (=) it is
assumed to be a Distinguished Name, with RDNs separated by commas (,)
or slashes (/ - the string must start with a slash to use this
syntax). An attempt is made to create a binary ASN.1 encoding from this
string. If that fails the type is set to KEY_ID with the literal string
value adopted as encoding.
- If the string value contains an @ the type depends on the
position of that character:
- If the string begins with @# the type is set to KEY_ID and
the string following that prefix is assumed to be the hex-encoded binary
value of the identity.
- If the string begins with @@ the type is set to USER_FQDN
and the encoding is the literal string after that prefix.
- If the string begins with @ the type is set to FQDN and the
encoding is the literal string after that prefix.
- All remaining strings containing an @ are assumed to be of
type USER_FQDN/RFC822 with the literal string value as encoding.
- If the value does not contain any @ or = characters it is
parsed as follows:
- If the value is an empty string, or equals %any,
0.0.0.0, ::, or * the type is set to ID_ANY, which matches any other
- If the value contains a colon (:) it is assumed to be an
IPv6 address. But if parsing the address and converting it to its binary
encoding fails the type is set to KEY_ID and the encoding is the literal
- For all other strings an attempt at parsing them as IPv4
addresses is made. If that fails the type is set to FQDN and the literal
value is adopted as encoding (this is where domain names and simple names
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:
IKE SAs as well as IPsec SAs can be rekeyed before they expire. This can be
configured using the following settings:
|IKE and IPsec SA
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
|IKE and IPsec SA
Randomization can be disabled by setting rekeyfuzz
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.
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.
- 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.
strongswan.conf(5), ipsec.secrets(5), ipsec(8)
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.