NAME¶
ipsec.conf - IPsec configuration and connections
DESCRIPTION¶
The optional
ipsec.conf file specifies most configuration and control
information for the strongSwan IPsec subsystem. The major exception is secrets
for authentication; see
ipsec.secrets(5). Its contents are not
security-sensitive.
The file is a text file, consisting of one or more
sections. White space
followed by
# followed by anything to the end of the line is a comment
and is ignored, as are empty lines which are not within a section.
A line which contains
include and a file name, separated by white space,
is replaced by the contents of that file, preceded and followed by empty
lines. If the file name is not a full pathname, it is considered to be
relative to the directory containing the including file. Such inclusions can
be nested. Only a single filename may be supplied, and it may not contain
white space, but it may include shell wildcards (see
sh(1)); for
example:
include ipsec.*.conf
The intention of the include facility is mostly to permit keeping information on
connections, or sets of connections, separate from the main configuration
file. This permits such connection descriptions to be changed, copied to the
other security gateways involved, etc., without having to constantly extract
them from the configuration file and then insert them back into it. Note also
the
also parameter (described below) which permits splitting a single
logical section (e.g. a connection description) into several actual sections.
A section begins with a line of the form:
type name
where
type indicates what type of section follows, and
name is an
arbitrary name which distinguishes the section from others of the same type.
Names must start with a letter and may contain only letters, digits, periods,
underscores, and hyphens. All subsequent non-empty lines which begin with
white space are part of the section; comments within a section must begin with
white space too. There may be only one section of a given type with a given
name.
Lines within the section are generally of the form
parameter=value
(note the mandatory preceding white space). There can be white space on either
side of the
=. Parameter names follow the same syntax as section names,
and are specific to a section type. Unless otherwise explicitly specified, no
parameter name may appear more than once in a section.
An empty
value stands for the system default value (if any) of the
parameter, i.e. it is roughly equivalent to omitting the parameter line
entirely. A
value may contain white space only if the entire
value is enclosed in double quotes (
"); a
value
cannot itself contain a double quote, nor may it be continued across more than
one line.
Numeric values are specified to be either an ``integer'' (a sequence of digits)
or a ``decimal number'' (sequence of digits optionally followed by `.' and
another sequence of digits).
There is currently one parameter which is available in any type of section:
- also
- the value is a section name; the parameters of that section
are appended to this section, as if they had been written as part of it.
The specified section must exist, must follow the current one, and must
have the same section type. (Nesting is permitted, and there may be more
than one also in a single section, although it is forbidden to
append the same section more than once.)
A section with name
%default specifies defaults for sections of the same
type. For each parameter in it, any section of that type which does not have a
parameter of the same name gets a copy of the one from the
%default
section. There may be multiple
%default sections of a given type, but
only one default may be supplied for any specific parameter name, and all
%default sections of a given type must precede all non-
%default
sections of that type.
%default sections may not contain the
also parameter.
Currently there are three types of sections: a
config section specifies
general configuration information for IPsec, a
conn section specifies
an IPsec connection, while a
ca section specifies special properties of
a certification authority.
CONN SECTIONS¶
A
conn section contains a
connection specification, defining a
network connection to be made using IPsec. The name given is arbitrary, and is
used to identify the connection. Here's a simple example:
conn snt
left=192.168.0.1
leftsubnet=10.1.0.0/16
right=192.168.0.2
rightsubnet=10.1.0.0/16
keyingtries=%forever
auto=add
A note on terminology: There are two kinds of communications going on:
transmission of user IP packets, and gateway-to-gateway negotiations for
keying, rekeying, and general control. The path to control the connection is
called 'ISAKMP SA' in IKEv1 and 'IKE SA' in the IKEv2 protocol. That what is
being negotiated, the kernel level data path, is called 'IPsec SA' or 'Child
SA'. strongSwan currently uses two separate keying daemons.
pluto
handles all IKEv1 connections,
charon is the daemon handling the IKEv2
protocol.
To avoid trivial editing of the configuration file to suit it to each system
involved in a connection, connection specifications are written in terms of
left and
right participants, rather than in terms of local and
remote. Which participant is considered
left or
right is
arbitrary; for every connection description an attempt is made to figure out
whether the local endpoint should act as the
left or
right
endpoint. This is done by matching the IP addresses defined for both endpoints
with the IP addresses assigned to local network interfaces. If a match is
found then the role (left or right) that matches is going to be considered
local. If no match is found during startup,
left is considered local.
This permits using identical connection specifications on both ends. There are
cases where there is no symmetry; a good convention is to use
left for
the local side and
right for the remote side (the first letters are a
good mnemonic).
Many of the parameters relate to one participant or the other; only the ones for
left are listed here, but every parameter whose name begins with
left has a
right counterpart, whose description is the same but
with
left and
right reversed.
Parameters are optional unless marked '(required)'.
CONN PARAMETERS¶
Unless otherwise noted, for a connection to work, in general it is necessary for
the two ends to agree exactly on the values of these parameters.
- aaa_identity = <id>
- defines the identity of the AAA backend used during IKEv2
EAP authentication. This is required if the EAP client uses a method that
verifies the server identity (such as EAP-TLS), but it does not match the
IKEv2 gateway identity.
- also = <name>
- includes conn section <name>.
- auth = esp | ah
- whether authentication should be done as part of ESP
encryption, or separately using the AH protocol; acceptable values are
esp (the default) and ah.
The IKEv2 daemon currently supports ESP only.
- authby = pubkey | rsasig | ecdsasig | psk |
eap | never | xauth...
- how the two security gateways should authenticate each
other; acceptable values are psk or secret for pre-shared
secrets, pubkey (the default) for public key signatures as well as
the synonyms rsasig for RSA digital signatures and ecdsasig
for Elliptic Curve DSA signatures. never can be used if negotiation
is never to be attempted or accepted (useful for shunt-only conns).
Digital signatures are superior in every way to shared secrets. IKEv1
additionally supports the values xauthpsk and xauthrsasig
that will enable eXtended AUTHentication (XAUTH) in addition to IKEv1 main
mode based on shared secrets or digital RSA signatures, respectively.
IKEv2 additionally supports the value eap, which indicates an
initiator to request EAP authentication. The EAP method to use is selected
by the server (see eap). This parameter is deprecated for IKEv2
connections, as two peers do not need to agree on an authentication
method. Use the leftauth parameter instead to define authentication
methods in IKEv2.
- auto = ignore | add | route | start
- what operation, if any, should be done automatically at
IPsec startup; currently-accepted values are add, route,
start and ignore (the default). add loads a
connection without starting it. route loads a connection and
installs kernel traps. If traffic is detected between leftsubnet
and rightsubnet , a connection is established. start loads a
connection and brings it up immediatly. ignore ignores the
connection. This is equal to delete a connection from the config file.
Relevant only locally, other end need not agree on it (but in general, for
an intended-to-be-permanent connection, both ends should use
auto=start to ensure that any reboot causes immediate
renegotiation).
- compress = yes | no
- whether IPComp compression of content is proposed on the
connection (link-level compression does not work on encrypted data, so to
be effective, compression must be done before encryption);
acceptable values are yes and no (the default). A value of
yes causes IPsec to propose both compressed and uncompressed, and
prefer compressed. A value of no prevents IPsec from proposing
compression; a proposal to compress will still be accepted.
- dpdaction = none | clear | hold |
restart
- controls the use of the Dead Peer Detection protocol (DPD,
RFC 3706) where R_U_THERE notification messages (IKEv1) or empty
INFORMATIONAL messages (IKEv2) are periodically sent in order to check the
liveliness of the IPsec peer. The values clear, hold, and
restart all activate DPD. If no activity is detected, all
connections with a dead peer are stopped and unrouted (clear), put
in the hold state (hold) or restarted (restart). For IKEv1,
the default is none which disables the active sending of R_U_THERE
notifications. Nevertheless pluto will always send the DPD Vendor ID
during connection set up in order to signal the readiness to act passively
as a responder if the peer wants to use DPD. For IKEv2, none does't
make sense, since all messages are used to detect dead peers. If
specified, it has the same meaning as the default (clear).
- dpddelay = 30s | <time>
- defines the period time interval with which R_U_THERE
messages/INFORMATIONAL exchanges are sent to the peer. These are only sent
if no other traffic is received. In IKEv2, a value of 0 sends no
additional INFORMATIONAL messages and uses only standard messages (such as
those to rekey) to detect dead peers.
- dpdtimeout = 150s | <time>
- defines the timeout interval, after which all connections
to a peer are deleted in case of inactivity. This only applies to IKEv1,
in IKEv2 the default retransmission timeout applies, as every exchange is
used to detect dead peers. See strongswan.conf(5) for a description
of the IKEv2 retransmission timeout.
- inactivity = <time>
- defines the timeout interval, after which a CHILD_SA is
closed if it did not send or receive any traffic. Currently supported in
IKEv2 connections only.
- eap = md5 | mschapv2 | radius | ... | <type> |
<type>-<vendor>
- defines the EAP type to propose as server if the client
requests EAP authentication. Currently supported values are aka for
EAP-AKA, gtc for EAP-GTC, md5 for EAP-MD5, mschapv2
for EAP-MS-CHAPv2, radius for the EAP-RADIUS proxy and sim
for EAP-SIM. Additionally, IANA assigned EAP method numbers are accepted,
or a definition in the form eap=type-vendor (e.g. eap=7-12345) can
be used to specify vendor specific EAP types. This parameter is deprecated
in the favour of leftauth.
To forward EAP authentication to a RADIUS server using the EAP-RADIUS
plugin, set eap=radius.
- eap_identity = <id>
- defines the identity the client uses to reply to a EAP
Identity request. If defined on the EAP server, the defined identity will
be used as peer identity during EAP authentication. The special value
%identity uses the EAP Identity method to ask the client for an EAP
identity. If not defined, the IKEv2 identity will be used as EAP
identity.
- esp = <cipher suites>
- comma-separated list of ESP encryption/authentication
algorithms to be used for the connection, e.g. aes128-sha256. The
notation is encryption-integrity[-dhgroup][-esnmodes].
If dh-group is specified, CHILD_SA setup and rekeying include a
separate diffe hellman exchange (IKEv2 only). Valid esnmodes (IKEv2
only) are esn and noesn. Specifying both negotiates Extended
Sequence number support with the peer, the defaut is noesn.
- forceencaps = yes | no
- force UDP encapsulation for ESP packets even if no NAT
situation is detected. This may help to surmount restrictive firewalls. In
order to force the peer to encapsulate packets, NAT detection payloads are
faked (IKEv2 only).
- ike = <cipher suites>
- comma-separated list of IKE/ISAKMP SA
encryption/authentication algorithms to be used, e.g.
aes128-sha1-modp2048. The notation is
encryption-integrity-dhgroup. In IKEv2, multiple algorithms and
proposals may be included, such as
aes128-aes256-sha1-modp1536-modp2048,3des-sha1-md5-modp1024.
- ikelifetime = 3h | <time>
- how long the keying channel of a connection (ISAKMP or IKE
SA) should last before being renegotiated. Also see EXPIRY/REKEY
below.
- installpolicy = yes | no
- decides whether IPsec policies are installed in the kernel
by the IKEv2 charon daemon for a given connection. Allows peaceful
cooperation e.g. with the Mobile IPv6 daemon mip6d who wants to control
the kernel policies. Acceptable values are yes (the default) and
no.
- keyexchange = ike | ikev1 | ikev2
- method of key exchange; which protocol should be used to
initialize the connection. Connections marked with ikev1 are
initiated with pluto, those marked with ikev2 with charon. An
incoming request from the remote peer is handled by the correct daemon,
unaffected from the keyexchange setting. Starting with strongSwan
4.5 the default value ike is a synonym for ikev2, whereas in
older strongSwan releases ikev1 was assumed.
- keyingtries = %forever | <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 %forever). The value %forever means
'never give up'. Relevant only locally, other end need not agree on
it.
- keylife
- synonym for lifetime.
- left = <ip address> | <fqdn> |
%defaultroute | %any
- (required) the IP address of the left participant's
public-network interface or one of several magic values. If it is
%defaultroute, left will be filled in automatically with the
local address of the default-route interface (as determined at IPsec
startup time and during configuration update). Either left or
right may be %defaultroute, but not both. The prefix
% in front of a fully-qualified domain name or an IP address will
implicitly set leftallowany=yes. If the domain name cannot be
resolved into an IP address at IPsec startup or update time then
left=%any and leftallowany=no will be assumed.
In case of an IKEv2 connection, the value %any for the local endpoint
signifies an address to be filled in (by automatic keying) during
negotiation. If the local peer initiates the connection setup the routing
table will be queried to determine the correct local IP address. In case
the local peer is responding to a connection setup then any IP address
that is assigned to a local interface will be accepted.
Note that specifying %any for the local endpoint is not supported by
the IKEv1 pluto daemon.
If %any is used for the remote endpoint it literally means any IP
address.
Please note that with the usage of wildcards multiple connection
descriptions might match a given incoming connection attempt. The most
specific description is used in that case.
- leftallowany = yes | no
- a modifier for left , making it behave as
%any although a concrete IP address has been assigned. Recommended
for dynamic IP addresses that can be resolved by DynDNS at IPsec startup
or update time. Acceptable values are yes and no (the
default).
- leftauth = <auth method>
- Authentication method to use locally (left) or require from
the remote (right) side. This parameter is supported in IKEv2 only.
Acceptable values are pubkey for public key authentication
(RSA/ECDSA), psk for pre-shared key authentication and eap
to (require the) use of the Extensible Authentication Protocol. To require
a trustchain public key strength for the remote side, specify the key type
followed by the strength in bits (for example rsa-2048 or
ecdsa-256). For eap, an optional EAP method can be appended.
Currently defined methods are eap-aka, eap-gtc,
eap-md5, eap-tls, eap-mschapv2 and eap-sim.
Alternatively, IANA assigned EAP method numbers are accepted. Vendor
specific EAP methods are defined in the form eap-type-vendor (e.g.
eap-7-12345).
- leftauth2 = <auth method>
- Same as leftauth, but defines an additional
authentication exchange. IKEv2 supports multiple authentication rounds
using "Multiple Authentication Exchanges" defined in RFC4739.
This allows, for example, separated authentication of host and user (IKEv2
only).
- leftca = <issuer dn> | %same
- the distinguished name of a certificate authority which is
required to lie in the trust path going from the left participant's
certificate up to the root certification authority.
- leftca2 = <issuer dn> | %same
- Same as leftca, but for the second authentication
round (IKEv2 only).
- leftcert = <path>
- the path to the left participant's X.509 certificate. The
file can be encoded either in PEM or DER format. OpenPGP certificates are
supported as well. Both absolute paths or paths relative to
/etc/ipsec.d/certs are accepted. By default leftcert sets
leftid to the distinguished name of the certificate's subject and
leftca to the distinguished name of the certificate's issuer. The
left participant's ID can be overridden by specifying a leftid
value which must be certified by the certificate, though.
- leftcert2 = <path>
- Same as leftcert, but for the second authentication
round (IKEv2 only).
- leftcertpolicy = <OIDs>
- Comma separated list of certificate policy OIDs the peers
certificate must have. OIDs are specified using the numerical dotted
representation (IKEv2 only).
- leftfirewall = yes | no
- whether the left participant is doing
forwarding-firewalling (including masquerading) using iptables for traffic
from leftsubnet, which should be turned off (for traffic to the
other subnet) once the connection is established; acceptable values are
yes and no (the default). May not be used in the same
connection description with leftupdown. Implemented as a parameter
to the default ipsec _updown script. See notes below. Relevant only
locally, other end need not agree on it.
If one or both security gateways are doing forwarding firewalling (possibly
including masquerading), and this is specified using the firewall
parameters, tunnels established with IPsec are exempted from it so that
packets can flow unchanged through the tunnels. (This means that all
subnets connected in this manner must have distinct, non-overlapping
subnet address blocks.) This is done by the default ipsec _updown
script (see pluto(8)).
In situations calling for more control, it may be preferable for the user to
supply his own updown script, which makes the appropriate
adjustments for his system.
- leftgroups = <group list>
- a comma separated list of group names. If the
leftgroups parameter is present then the peer must be a member of
at least one of the groups defined by the parameter. Group membership must
be certified by a valid attribute certificate stored in
/etc/ipsec.d/acerts/ thas has been issued to the peer by a trusted
Authorization Authority stored in /etc/ipsec.d/aacerts/.
Attribute certificates are not supported in IKEv2 yet.
- lefthostaccess = yes | no
- inserts a pair of INPUT and OUTPUT iptables rules using the
default ipsec _updown script, thus allowing access to the host
itself in the case where the host's internal interface is part of the
negotiated client subnet. Acceptable values are yes and no
(the default).
- leftid = <id>
- how the left participant should be identified for
authentication; defaults to left. Can be an IP address or a
fully-qualified domain name preceded by @ (which is used as a
literal string and not resolved).
- leftid2 = <id>
- identity to use for a second authentication for the left
participant (IKEv2 only); defaults to leftid.
- leftikeport = <port>
- UDP port the left participant uses for IKE communication.
Currently supported in IKEv2 connections only. If unspecified, port 500 is
used with the port floating to 4500 if a NAT is detected or MOBIKE is
enabled. Specifying a local IKE port different from the default
additionally requires a socket implementation that listens to this
port.
- leftnexthop = %direct | %defaultroute | <ip
address> | <fqdn>
- this parameter is usually not needed any more because the
NETKEY IPsec stack does not require explicit routing entries for the
traffic to be tunneled. If leftsourceip is used with IKEv1 then
leftnexthop must still be set in order for the source routes to
work properly.
- leftprotoport = <protocol>/<port>
- restrict the traffic selector to a single protocol and/or
port. Examples: leftprotoport=tcp/http or leftprotoport=6/80
or leftprotoport=udp
- leftrsasigkey = %cert | <raw rsa public
key>
- the left participant's public key for RSA signature
authentication, in RFC 2537 format using ttodata(3) encoding. The
magic value %none means the same as not specifying a value (useful
to override a default). The value %cert (the default) means that
the key is extracted from a certificate. The identity used for the left
participant must be a specific host, not %any or another magic
value. Caution: if two connection descriptions specify different
public keys for the same leftid, confusion and madness will
ensue.
- leftsendcert = never | no | ifasked | always
| yes
- Accepted values are never or no,
always or yes, and ifasked (the default), the latter
meaning that the peer must send a certificate request payload in order to
get a certificate in return.
- leftsourceip = %config | %cfg | %modeconfig |
%modecfg | <ip address>
- The internal source IP to use in a tunnel, also known as
virtual IP. If the value is one of the synonyms %config,
%cfg, %modeconfig, or %modecfg, an address is
requested from the peer. In IKEv2, a statically defined address is also
requested, since the server may change it.
- rightsourceip = %config |
<network>/<netmask> | %poolname
- The internal source IP to use in a tunnel for the remote
peer. If the value is %config on the responder side, the initiator
must propose an address which is then echoed back. Also supported are
address pools expressed as network/netmask or the use
of an external IP address pool using % poolname, where
poolname is the name of the IP address pool used for the
lookup.
- leftsubnet = <ip subnet>
- private subnet behind the left participant, expressed as
network/netmask; if omitted, essentially assumed to
be left/32, signifying that the left end of the connection
goes to the left participant only. When using IKEv2, the configured subnet
of the peers may differ, the protocol narrows it to the greatest common
subnet. Further, IKEv2 supports multiple subnets separated by commas.
IKEv1 only interprets the first subnet of such a definition.
- leftsubnetwithin = <ip subnet>
- the peer can propose any subnet or single IP address that
fits within the range defined by leftsubnetwithin. Not relevant for
IKEv2, as subnets are narrowed.
- leftupdown = <path>
- what ``updown'' script to run to adjust routing and/or
firewalling when the status of the connection changes (default ipsec
_updown). May include positional parameters separated by white space
(although this requires enclosing the whole string in quotes); including
shell metacharacters is unwise. See pluto(8) for details. Relevant
only locally, other end need not agree on it. IKEv2 uses the updown script
to insert firewall rules only, since routing has been implemented directly
into charon.
- lifebytes = <number>
- the number of bytes transmitted over an IPsec SA before it
expires (IKEv2 only).
- lifepackets = <number>
- the number of packets transmitted over an IPsec SA before
it expires (IKEv2 only).
- lifetime = 1h | <time>
- how long a particular instance of a connection (a set of
encryption/authentication keys for user packets) should last, from
successful negotiation to expiry; acceptable values are an integer
optionally followed by s (a time in seconds) or a decimal number
followed by m, h, or d (a time in minutes, hours, or
days respectively) (default 1h, maximum 24h). Normally, the
connection is renegotiated (via the keying channel) before it expires (see
margintime). The two ends need not exactly agree on
lifetime, although if they do not, there will be some clutter of
superseded connections on the end which thinks the lifetime is longer.
Also see EXPIRY/REKEY below.
- marginbytes = <number>
- how many bytes before IPsec SA expiry (see
lifebytes) should attempts to negotiate a replacement begin (IKEv2
only).
- marginpackets = <number>
- how many packets before IPsec SA expiry (see
lifepackets) should attempts to negotiate a replacement begin
(IKEv2 only).
- margintime = 9m | <time>
- how long before connection expiry or keying-channel expiry
should attempts to negotiate a replacement begin; acceptable values as for
lifetime (default 9m). Relevant only locally, other end need
not agree on it. Also see EXPIRY/REKEY below.
- mark = <value>[/<mask>]
- sets an XFRM mark in the inbound and outbound IPsec SAs and
policies. If the mask is missing then a default mask of 0xffffffff
is assumed.
- mark_in = <value>[/<mask>]
- sets an XFRM mark in the inbound IPsec SA and policy. If
the mask is missing then a default mask of 0xffffffff is
assumed.
- mark_out = <value>[/<mask>]
- sets an XFRM mark in the outbound IPsec SA and policy. If
the mask is missing then a default mask of 0xffffffff is
assumed.
- mobike = yes | no
- enables the IKEv2 MOBIKE protocol defined by RFC 4555.
Accepted values are yes (the default) and no. If set to
no, the IKEv2 charon daemon will not actively propose MOBIKE as
initiator and ignore the MOBIKE_SUPPORTED notify as responder.
- modeconfig = push | pull
- defines which mode is used to assign a virtual IP. Accepted
values are push and pull (the default). Currently relevant
for IKEv1 only since IKEv2 always uses the configuration payload in pull
mode. Cisco VPN gateways usually operate in push mode.
- pfs = yes | no
- whether Perfect Forward Secrecy of keys is desired on the
connection's keying channel (with PFS, penetration of the key-exchange
protocol does not compromise keys negotiated earlier); acceptable values
are yes (the default) and no. IKEv2 always uses PFS for
IKE_SA rekeying whereas for CHILD_SA rekeying PFS is enforced by defining
a Diffie-Hellman modp group in the esp parameter.
- pfsgroup = <modp group>
- defines a Diffie-Hellman group for perfect forward secrecy
in IKEv1 Quick Mode differing from the DH group used for IKEv1 Main Mode
(IKEv1 only).
- reauth = yes | no
- whether rekeying of an IKE_SA should also reauthenticate
the peer. In IKEv1, reauthentication is always done. In IKEv2, a value of
no rekeys without uninstalling the IPsec SAs, a value of yes
(the default) creates a new IKE_SA from scratch and tries to recreate all
IPsec SAs.
- rekey = yes | no
- whether a connection should be renegotiated when it is
about to expire; acceptable values are yes (the default) and
no. The two ends need not agree, but while a value of no
prevents pluto/charon from requesting renegotiation, it does not prevent
responding to renegotiation requested from the other end, so no
will be largely ineffective unless both ends agree on it.
- rekeyfuzz = 100% | <percentage>
- maximum percentage by which marginbytes,
marginpackets and margintime should be randomly increased to
randomize rekeying intervals (important for hosts with many connections);
acceptable values are an integer, which may exceed 100, followed by a `%'
(defaults to 100%). The value of marginTYPE, after this
random increase, must not exceed lifeTYPE (where TYPE is one of
bytes, packets or time). The value 0% will
suppress randomization. Relevant only locally, other end need not agree on
it. Also see EXPIRY/REKEY below.
- rekeymargin
- synonym for margintime.
- reqid = <number>
- sets the reqid for a given connection to a pre-configured
fixed value.
- tfc = <value>
- number of bytes to pad ESP payload data to. Traffic Flow
Confidentiality is currently supported in IKEv2 and applies to outgoing
packets only. The special value %mtu fills up ESP packets with
padding to have the size of the MTU.
- type = tunnel | transport | transport_proxy |
passthrough | drop
- the type of the connection; currently the accepted values
are tunnel (the default) signifying a host-to-host, host-to-subnet,
or subnet-to-subnet tunnel; transport, signifying host-to-host
transport mode; transport_proxy, signifying the special Mobile IPv6
transport proxy mode; passthrough, signifying that no IPsec
processing should be done at all; drop, signifying that packets
should be discarded; and reject, signifying that packets should be
discarded and a diagnostic ICMP returned (reject is currently not
supported by the NETKEY stack of the Linux 2.6 kernel). The IKEv2 daemon
charon currently supports tunnel, transport, and
transport_proxy connection types, only.
- xauth = client | server
- specifies the role in the XAUTH protocol if activated by
authby=xauthpsk or authby=xauthrsasig. Accepted values are
server and client (the default).
The following parameters are relevant to IKEv2 Mediation Extension operation
only.
- mediation = yes | no
- whether this connection is a mediation connection, ie.
whether this connection is used to mediate other connections. Mediation
connections create no child SA. Acceptable values are no (the
default) and yes.
- mediated_by = <name>
- the name of the connection to mediate this connection
through. If given, the connection will be mediated through the named
mediation connection. The mediation connection must set
mediation=yes.
- me_peerid = <id>
- ID as which the peer is known to the mediation server, ie.
which the other end of this connection uses as its leftid on its
connection to the mediation server. This is the ID we request the
mediation server to mediate us with. If me_peerid is not given, the
rightid of this connection will be used as peer ID.
CA SECTIONS¶
These are optional sections that can be used to assign special parameters to a
Certification Authority (CA). Because the daemons automatically import CA
certificates from
/etc/ipsec.d/cacerts, there is no need to explicitly
add them with a CA section, unless you want to assign special parameters (like
a CRL) to a CA.
- also = <name>
- includes ca section <name>.
- auto = ignore | add
- currently can have either the value ignore (the
default) or add.
- cacert = <path>
- defines a path to the CA certificate either relative to
/etc/ipsec.d/cacerts or as an absolute path.
- crluri = <uri>
- defines a CRL distribution point (ldap, http, or file
URI)
- crluri1
- synonym for crluri.
- crluri2 = <uri>
- defines an alternative CRL distribution point (ldap, http,
or file URI)
- ldaphost = <hostname>
- defines an ldap host. Currently used by IKEv1 only.
- ocspuri = <uri>
- defines an OCSP URI.
- ocspuri1
- synonym for ocspuri.
- ocspuri2 = <uri>
- defines an alternative OCSP URI. Currently used by IKEv2
only.
- certuribase = <uri>
- defines the base URI for the Hash and URL feature supported
by IKEv2. Instead of exchanging complete certificates, IKEv2 allows to
send an URI that resolves to the DER encoded certificate. The certificate
URIs are built by appending the SHA1 hash of the DER encoded certificates
to this base URI.
CONFIG SECTIONS¶
At present, the only
config section known to the IPsec software is the
one named
setup, which contains information used when the software is
being started. Here's an example:
config setup
plutodebug=all
crlcheckinterval=10m
strictcrlpolicy=yes
Parameters are optional unless marked ``(required)''. The currently-accepted
parameter names in a
config setup section affecting both
daemons are:
- cachecrls = yes | no
- certificate revocation lists (CRLs) fetched via http or
ldap will be cached in /etc/ipsec.d/crls/ under a unique file name
derived from the certification authority's public key. Accepted values are
yes and no (the default). Only relevant for IKEv1, as CRLs
are always cached in IKEv2.
- charonstart = yes | no
- whether to start the IKEv2 charon daemon or not. The
default is yes if starter was compiled with IKEv2 support.
- plutostart = yes | no
- whether to start the IKEv1 pluto daemon or not. The default
is yes if starter was compiled with IKEv1 support.
- strictcrlpolicy = yes | ifuri | no
- defines if a fresh CRL must be available in order for the
peer authentication based on RSA signatures to succeed. IKEv2 additionally
recognizes ifuri which reverts to yes if at least one CRL
URI is defined and to no if no URI is known.
- uniqueids = yes | no | replace | keep
- whether a particular participant ID should be kept unique,
with any new (automatically keyed) connection using an ID from a different
IP address deemed to replace all old ones using that ID; acceptable values
are yes (the default) and no. Participant IDs normally
are unique, so a new (automatically-keyed) connection using the
same ID is almost invariably intended to replace an old one. The IKEv2
daemon also accepts the value replace wich is identical to
yes and the value keep to reject new IKE_SA setups and keep
the duplicate established earlier.
The following
config section parameters are used by the IKEv1 Pluto
daemon only:
- crlcheckinterval = 0s | <time>
- interval in seconds. CRL fetching is enabled if the value
is greater than zero. Asynchronous, periodic checking for fresh CRLs is
currently done by the IKEv1 Pluto daemon only.
- keep_alive = 20s | <time>
- interval in seconds between NAT keep alive packets, the
default being 20 seconds.
- nat_traversal = yes | no
- activates NAT traversal by accepting source ISAKMP ports
different from udp/500 and being able of floating to udp/4500 if a NAT
situation is detected. Accepted values are yes and no (the
default). Used by IKEv1 only, NAT traversal is always being active in
IKEv2.
- nocrsend = yes | no
- no certificate request payloads will be sent.
- pkcs11initargs = <args>
- non-standard argument string for PKCS#11 C_Initialize()
function; required by NSS softoken.
- pkcs11module = <args>
- defines the path to a dynamically loadable PKCS #11
library.
- pkcs11keepstate = yes | no
- PKCS #11 login sessions will be kept during the whole
lifetime of the keying daemon. Useful with pin-pad smart card readers.
Accepted values are yes and no (the default).
- pkcs11proxy = yes | no
- Pluto will act as a PKCS #11 proxy accessible via the whack
interface. Accepted values are yes and no (the
default).
- plutodebug = none | <debug list> |
all
- how much pluto debugging output should be logged. An empty
value, or the magic value none, means no debugging output (the
default). The magic value all means full output. Otherwise only the
specified types of output (a quoted list, names without the
--debug- prefix, separated by white space) are enabled; for details
on available debugging types, see pluto(8).
- plutostderrlog = <file>
- Pluto will not use syslog, but rather log to stderr, and
redirect stderr to <file>.
- postpluto = <command>
- shell command to run after starting pluto (e.g., to remove
a decrypted copy of the ipsec.secrets file). It's run in a very
simple way; complexities like I/O redirection are best hidden within a
script. Any output is redirected for logging, so running interactive
commands is difficult unless they use /dev/tty or equivalent for
their interaction. Default is none.
- prepluto = <command>
- shell command to run before starting pluto (e.g., to
decrypt an encrypted copy of the ipsec.secrets file). It's run in a
very simple way; complexities like I/O redirection are best hidden within
a script. Any output is redirected for logging, so running interactive
commands is difficult unless they use /dev/tty or equivalent for
their interaction. Default is none.
- virtual_private = <networks>
- defines private networks using a wildcard notation.
The following
config section parameters are used by the IKEv2 charon
daemon only:
- charondebug = <debug list>
- how much charon debugging output should be logged. A comma
separated list containing type level/pairs may be specified, e.g: dmn
3, ike 1, net -1. Acceptable values for types are dmn, mgr, ike,
chd, job, cfg, knl, net, enc, lib and the level is one of -1, 0, 1,
2, 3, 4 (for silent, audit, control, controlmore, raw, private). For
more flexibility see LOGGER CONFIGURATION in strongswan.conf(5).
IKEv2 EXPIRY/REKEY¶
The IKE SAs and IPsec SAs negotiated by the daemon can be configured to expire
after a specific amount of time. For IPsec SAs this can also happen after a
specified number of transmitted packets or transmitted bytes. The following
settings can be used to configure this:
Setting |
Default |
Setting |
Default |
|
IKE SA |
|
IPsec SA |
|
ikelifetime |
3h |
lifebytes |
- |
|
|
lifepackets |
- |
|
|
lifetime |
1h |
Rekeying¶
IKE SAs as well as IPsec SAs can be rekeyed before they expire. This can be
configured using the following settings:
Setting |
Default |
Setting |
Default |
|
IKE and IPsec SA |
|
IPsec SA |
|
margintime |
9m |
marginbytes |
- |
|
|
marginpackets |
- |
Randomization¶
To avoid collisions the specified margins are increased randomly before
subtracting them from the expiration limits (see formula below). This is
controlled by the
rekeyfuzz setting:
Setting |
Default |
|
IKE and IPsec SA |
|
rekeyfuzz |
100% |
Randomization can be disabled by setting
rekeyfuzz to
0%.
The following formula is used to calculate the rekey time of IPsec SAs:
rekeytime = lifetime - (margintime + random(0, margintime * rekeyfuzz))
It applies equally to IKE SAs and byte and packet limits for IPsec SAs.
Example¶
Let's consider the default configuration:
lifetime = 1h
margintime = 9m
rekeyfuzz = 100%
From the formula above follows that the rekey time lies between:
rekeytime_min = 1h - (9m + 9m) = 42m
rekeytime_max = 1h - (9m + 0m) = 51m
Thus, the daemon will attempt to rekey the IPsec SA at a random time between 42
and 51 minutes after establishing the SA. Or, in other words, between 9 and 18
minutes before the SA expires.
Notes¶
- •
- Since the rekeying of an SA needs some time, the margin
values must not be too low.
- •
- The value margin... + margin... * rekeyfuzz must not
exceed the original limit. For example, specifying margintime = 30m
in the default configuration is a bad idea as there is a chance that the
rekey time equals zero and, thus, rekeying gets disabled.
FILES¶
/etc/ipsec.conf
/etc/ipsec.d/aacerts
/etc/ipsec.d/acerts
/etc/ipsec.d/cacerts
/etc/ipsec.d/certs
/etc/ipsec.d/crls
SEE ALSO¶
strongswan.conf(5),
ipsec.secrets(5),
ipsec(8),
pluto(8)
HISTORY¶
Originally written for the FreeS/WAN project by Henry Spencer. Updated and
extended for the strongSwan project <
http://www.strongswan.org> by
Tobias Brunner, Andreas Steffen and Martin Willi.
BUGS¶
If conns are to be added before DNS is available,
left=FQDN will
fail.