IPSEC.CONF(5) strongSwan IPSEC.CONF(5)NAMEipsec.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 sec‐
tion.
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:
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., with‐
out 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 connec‐
tion 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 arbi‐
trary 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
parameter=value
(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
%default section or via also parameter (see below). A value may con‐
tain 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 mul‐
tiple lines by ending them with \ characters (following lines don't
have to begin with white space, as that will be preserved). Addition‐
ally, 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 sec‐
tion:
also the value is a section name; the parameters of that section are
inherited by the current section. Parameters in the current sec‐
tion always override inherited parameters, even if an also fol‐
lows 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 ref‐
erenced 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 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 sepa‐
rate keying daemons, pluto and charon. This manual does not discuss
pluto options anymore, but only charon that since strongSwan 5.0 sup‐
ports 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 arbi‐
trary; for every connection description an attempt is made to figure
out whether the local endpoint should act as the left or right end‐
point. This is done by matching the IP addresses defined for both end‐
points 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 con‐
sidered local. This permits using identical connection specifications
on both ends. There are cases where there is no symmetry; a good con‐
vention 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 nec‐
essary for the two ends to agree exactly on the values of these parame‐
ters.
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 connec‐
tion, 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.
also = <name>
includes conn section <name>.
auth = <value>
was used by the pluto IKEv1 daemon to use AH integrity protec‐
tion for ESP encrypted packets, but is not supported in charon.
The ah keyword specifies algorithms to use for integrity protec‐
tion 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, pub‐
key (the default) for public key signatures as well as the syn‐
onyms rsasig for RSA digital signatures and ecdsasig for Ellip‐
tic 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 signa‐
tures, 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 con‐
nection 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 connec‐
tion (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 and determine the action to perform
on a timeout. With clear the connection is closed with no fur‐
ther 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 mes‐
sages/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 stan‐
dard 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 nota‐
tion 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 exten‐
sive 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 pro‐
posal 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 negoti‐
ates 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 or
IKEv2 fragmentation as per RFC 7383). Acceptable values are
yes, force and no (the default). Fragmented IKE 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 mes‐
sages will be sent in fragments. If set to force (only sup‐
ported for IKEv1) the initial IKE message will already be frag‐
mented 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 con‐
figured 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 pro‐
posal 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
below.
installpolicy = yes | no
decides whether IPsec policies are installed in the kernel by
the charon daemon for a given connection. Allows peaceful coop‐
eration e.g. with the Mobile IPv6 daemon mip6d who wants to con‐
trol 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 con‐
nection. 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'. Rel‐
evant 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 inter‐
face 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 spec‐
ified, and multiple addresses, ranges and subnets can be sepa‐
rated 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 con‐
crete 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 authenti‐
cation, eap to (require the) use of the Extensible Authentica‐
tion Protocol in IKEv2, and xauth for IKEv1 eXtended Authentica‐
tion.
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). Unless disabled in
strongswan.conf(5) 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 authen‐
tication may be configured. The syntax is the same as above.
For example, with pubkey-sha384-sha256 a public key signature
scheme with either SHA-384 or SHA-256 would get used for authen‐
tication, in that order and depending on the hash algorithms
supported by the peer. If no specific hash algorithms are con‐
figured, the default is to prefer an algorithm that matches or
exceeds the strength of the signature key.
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 authen‐
tication 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 partici‐
pant'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 cer‐
tificate must have. OIDs are specified using the numerical dot‐
ted representation.
leftdns = <servers>
Comma separated list of DNS server addresses to exchange as con‐
figuration 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 left‐
subnet, 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 con‐
nection 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 fire‐
walling (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 appro‐
priate adjustments for his system.
leftgroups = <group list>
a comma separated list of group names. If the leftgroups parame‐
ter 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 authentica‐
tion; defaults to left or the subject of the certificate config‐
ured 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 deter‐
mined automatically and the string is converted to the appropri‐
ate 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 iden‐
tity 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 inter‐
preted as hex encoding, otherwise the string is used as is as
the identification data. Note: The latter implies that no con‐
version 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 pre‐
fixes 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 pre‐
vents the daemon from sending IDr in its IKE_AUTH request and
will allow it to verify the configured identity against the sub‐
ject and subjectAltNames contained in the responder's certifi‐
cate (otherwise it is only compared with the IDr returned by the
responder). The IDr sent by the initiator might otherwise pre‐
vent 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 partic‐
ipant (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, DER or SSH encoding. Both
absolute paths or paths relative to /etc/ipsec.d/certs are
accepted.
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 certifi‐
cate 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> | <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/net‐
mask 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 lookup.
leftsubnet = <ip subnet>[[<proto/port>]][,...]
private subnet behind the left participant, expressed as net‐
work/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 inter‐
prets 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 sub‐
net.
Examples: leftsubnet=10.0.0.1[tcp/http],10.0.0.2[6/80] or left‐
subnet=fec1::1[udp],10.0.0.0/16[/53]. Instead of omitting
either value %any can be used to the same effect, e.g. leftsub‐
net=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 signif‐
icant 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 mul‐
tiple dynamic selectors, each having a potentially different
protocol/port definition.
leftupdown = <path>
what ``updown'' script to run to adjust routing and/or fire‐
walling 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 encryp‐
tion/authentication keys for user packets) should last, from
successful negotiation to expiry; acceptable values are an inte‐
ger 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 connec‐
tion is renegotiated (via the keying channel) before it expires
(see margintime). The two ends need not exactly agree on life‐
time, 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.
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); accept‐
able 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 randomiza‐
tion. Relevant only locally, other end need not agree on it.
Also see EXPIRY/REKEY below.
rekeymargin
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 protection.
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 Confi‐
dentiality is currently supported in IKEv2 and applies to outgo‐
ing 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 media‐
tion=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 con‐
nection 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 parame‐
ters to a Certification Authority (CA). Because the daemons automati‐
cally 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 sup‐
ported by IKEv2. Instead of exchanging complete certifi‐
cates, 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 cer‐
tificates 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 CON‐
FIGURATION 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 ear‐
lier.
IDENTITY PARSING
The type and binary encoding of identity strings specified in
leftid are 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[6], 0.0.0.0, ::, or * the type is set to
ID_ANY, which matches any other identity.
· 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 lit‐
eral value.
· For all other strings an attempt at parsing them
as IPv4 addresses is made. If that fails the type
is set to FQDN and the literal value is adopted as
encoding (this is where domain names and simple
names end up).
SA EXPIRY/REKEY
The IKE SAs and IPsec SAs negotiated by the daemon can be con‐
figured 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 ALSOstrongswan.conf(5), ipsec.secrets(5), ipsec(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.
5.3.5 2012-06-26 IPSEC.CONF(5)
