NAME¶
ipsec.conf - IPsec configuration and connections
DESCRIPTION¶
The optional
ipsec.conf file specifies most configuration and control
information for the strongSwan IPsec subsystem. The major exception is secrets
for authentication; see
ipsec.secrets(5). Its contents are not
security-sensitive.
The file is a text file, consisting of one or more
sections. White space
followed by
# followed by anything to the end of the line is a comment
and is ignored, as are empty lines which are not within a section.
A line which contains
include and a file name, separated by white space,
is replaced by the contents of that file, preceded and followed by empty
lines. If the file name is not a full pathname, it is considered to be
relative to the directory containing the including file. Such inclusions can
be nested. Only a single filename may be supplied, and it may not contain
white space, but it may include shell wildcards (see
sh(1)); for
example:
include ipsec.*.conf
The intention of the include facility is mostly to permit keeping information on
connections, or sets of connections, separate from the main configuration
file. This permits such connection descriptions to be changed, copied to the
other security gateways involved, etc., without having to constantly extract
them from the configuration file and then insert them back into it. Note also
the
also parameter (described below) which permits splitting a single
logical section (e.g. a connection description) into several actual sections.
A section begins with a line of the form:
type name
where
type indicates what type of section follows, and
name is an
arbitrary name which distinguishes the section from others of the same type.
Names must start with a letter and may contain only letters, digits, periods,
underscores, and hyphens. All subsequent non-empty lines which begin with
white space are part of the section; comments within a section must begin with
white space too. There may be only one section of a given type with a given
name.
Lines within the section are generally of the form
parameter=value
(note the mandatory preceding white space). There can be white space on either
side of the
=. Parameter names follow the same syntax as section names,
and are specific to a section type. Unless otherwise explicitly specified, no
parameter name may appear more than once in a section.
An empty
value stands for the system default value (if any) of the
parameter, i.e. it is roughly equivalent to omitting the parameter line
entirely. A
value may contain white space only if the entire
value is enclosed in double quotes (
"); a
value
cannot itself contain a double quote, nor may it be continued across more than
one line.
Numeric values are specified to be either an ``integer'' (a sequence of digits)
or a ``decimal number'' (sequence of digits optionally followed by `.' and
another sequence of digits).
There is currently one parameter which is available in any type of section:
- also
- the value is a section name; the parameters of that section are appended
to this section, as if they had been written as part of it. The specified
section must exist, must follow the current one, and must have the same
section type. (Nesting is permitted, and there may be more than one
also in a single section, although it is forbidden to append the
same section more than once.)
A section with name
%default specifies defaults for sections of the same
type. For each parameter in it, any section of that type which does not have a
parameter of the same name gets a copy of the one from the
%default
section. There may be multiple
%default sections of a given type, but
only one default may be supplied for any specific parameter name, and all
%default sections of a given type must precede all non-
%default
sections of that type.
%default sections may not contain the
also parameter.
Currently there are three types of sections: a
config section specifies
general configuration information for IPsec, a
conn section specifies
an IPsec connection, while a
ca section specifies special properties of
a certification authority.
CONN SECTIONS¶
A
conn section contains a
connection specification, defining a
network connection to be made using IPsec. The name given is arbitrary, and is
used to identify the connection. Here's a simple example:
conn snt
left=192.168.0.1
leftsubnet=10.1.0.0/16
right=192.168.0.2
rightsubnet=10.1.0.0/16
keyingtries=%forever
auto=add
A note on terminology: There are two kinds of communications going on:
transmission of user IP packets, and gateway-to-gateway negotiations for
keying, rekeying, and general control. The path to control the connection is
called 'ISAKMP SA' in IKEv1 and 'IKE SA' in the IKEv2 protocol. That what is
being negotiated, the kernel level data path, is called 'IPsec SA' or 'Child
SA'. strongSwan previously used two separate keying daemons,
pluto and
charon. This manual does not discuss
pluto options anymore, but
only
charon that since strongSwan 5.0 supports both IKEv1 and IKEv2.
To avoid trivial editing of the configuration file to suit it to each system
involved in a connection, connection specifications are written in terms of
left and
right participants, rather than in terms of local and
remote. Which participant is considered
left or
right is
arbitrary; for every connection description an attempt is made to figure out
whether the local endpoint should act as the
left or
right
endpoint. This is done by matching the IP addresses defined for both endpoints
with the IP addresses assigned to local network interfaces. If a match is
found then the role (left or right) that matches is going to be considered
local. If no match is found during startup,
left is considered local.
This permits using identical connection specifications on both ends. There are
cases where there is no symmetry; a good convention is to use
left for
the local side and
right for the remote side (the first letters are a
good mnemonic).
Many of the parameters relate to one participant or the other; only the ones for
left are listed here, but every parameter whose name begins with
left has a
right counterpart, whose description is the same but
with
left and
right reversed.
Parameters are optional unless marked '(required)'.
CONN PARAMETERS¶
Unless otherwise noted, for a connection to work, in general it is necessary for
the two ends to agree exactly on the values of these parameters.
- aaa_identity = <id>
- defines the identity of the AAA backend used during IKEv2 EAP
authentication. This is required if the EAP client uses a method that
verifies the server identity (such as EAP-TLS), but it does not match the
IKEv2 gateway identity.
- aggressive = yes | no
- whether to use IKEv1 Aggressive or Main Mode (the default).
- ah = <cipher suites>
- comma-separated list of AH algorithms to be used for the connection, e.g.
sha1-sha256-modp1024. The notation is integrity[-dhgroup].
For IKEv2, multiple algorithms (separated by -) of the same type can be
included in a single proposal. IKEv1 only includes the first algorithm in
a proposal. Only either the ah or esp keyword may be used,
AH+ESP bundles are not supported.
There is no default, by default ESP is used. The daemon adds its extensive
default proposal to the configured value. To restrict it to the configured
proposal an exclamation mark (!) can be added at the end.
If dh-group is specified, CHILD_SA/Quick Mode setup and rekeying
include a separate Diffie-Hellman exchange.
- also = <name>
- includes conn section <name>.
- auth = <value>
- was used by the pluto IKEv1 daemon to use AH integrity protection
for ESP encrypted packets, but is not supported in charon. The ah
keyword specifies algorithms to use for integrity protection with AH, but
without encryption. AH+ESP bundles are not supported.
- authby = pubkey | rsasig | ecdsasig | psk | secret | never |
xauthpsk | xauthrsasig
- how the two security gateways should authenticate each other; acceptable
values are psk or secret for pre-shared secrets,
pubkey (the default) for public key signatures as well as the
synonyms rsasig for RSA digital signatures and ecdsasig for
Elliptic Curve DSA signatures. never can be used if negotiation is
never to be attempted or accepted (useful for shunt-only conns). Digital
signatures are superior in every way to shared secrets. IKEv1 additionally
supports the values xauthpsk and xauthrsasig that will
enable eXtended AUTHentication (XAUTH) in addition to IKEv1 main mode
based on shared secrets or digital RSA signatures, respectively. This
parameter is deprecated, as two peers do not need to agree on an
authentication method in IKEv2. Use the leftauth parameter instead
to define authentication methods.
- auto = ignore | add | route | start
- what operation, if any, should be done automatically at IPsec startup;
currently-accepted values are add, route, start and
ignore (the default). add loads a connection without
starting it. route loads a connection and installs kernel traps. If
traffic is detected between leftsubnet and rightsubnet, a
connection is established. start loads a connection and brings it
up immediately. ignore ignores the connection. This is equal to
deleting a connection from the config file. Relevant only locally, other
end need not agree on it.
- closeaction = none | clear | hold | restart
- defines the action to take if the remote peer unexpectedly closes a
CHILD_SA (see dpdaction for meaning of values). A closeaction
should not be used if the peer uses reauthentication or uniquids
checking, as these events might trigger the defined action when not
desired.
- compress = yes | no
- whether IPComp compression of content is proposed on the connection
(link-level compression does not work on encrypted data, so to be
effective, compression must be done before encryption); acceptable
values are yes and no (the default). A value of yes
causes the daemon to propose both compressed and uncompressed, and prefer
compressed. A value of no prevents the daemon from proposing or
accepting compression.
- dpdaction = none | clear | hold | restart
- controls the use of the Dead Peer Detection protocol (DPD, RFC 3706) where
R_U_THERE notification messages (IKEv1) or empty INFORMATIONAL messages
(IKEv2) are periodically sent in order to check the liveliness of the
IPsec peer. The values clear, hold, and restart all
activate DPD. If no activity is detected, all connections with a dead peer
are stopped and unrouted (clear), put in the hold state
(hold) or restarted (restart). The default is none
which disables the active sending of DPD messages.
- dpddelay = 30s | <time>
- defines the period time interval with which R_U_THERE
messages/INFORMATIONAL exchanges are sent to the peer. These are only sent
if no other traffic is received. In IKEv2, a value of 0 sends no
additional INFORMATIONAL messages and uses only standard messages (such as
those to rekey) to detect dead peers.
- dpdtimeout = 150s | <time>
- defines the timeout interval, after which all connections to a peer are
deleted in case of inactivity. This only applies to IKEv1, in IKEv2 the
default retransmission timeout applies, as every exchange is used to
detect dead peers.
- inactivity = <time>
- defines the timeout interval, after which a CHILD_SA is closed if it did
not send or receive any traffic. The inactivity counter is reset during
CHILD_SA rekeying. This means that the inactivity timeout must be smaller
than the rekeying interval to have any effect.
- eap_identity = <id>
- defines the identity the client uses to reply to an EAP Identity request.
If defined on the EAP server, the defined identity will be used as peer
identity during EAP authentication. The special value %identity
uses the EAP Identity method to ask the client for an EAP identity. If not
defined, the IKEv2 identity will be used as EAP identity.
- esp = <cipher suites>
- comma-separated list of ESP encryption/authentication algorithms to be
used for the connection, e.g. aes128-sha256. The notation is
encryption-integrity[-dhgroup][-esnmode]. For IKEv2, multiple
algorithms (separated by -) of the same type can be included in a single
proposal. IKEv1 only includes the first algorithm in a proposal. Only
either the ah or esp keyword may be used, AH+ESP bundles are
not supported.
Defaults to aes128-sha1,3des-sha1. The daemon adds its extensive
default proposal to this default or the configured value. To restrict it
to the configured proposal an exclamation mark (!) can be added at
the end.
Note: As a responder the daemon accepts the first supported proposal
received from the peer. In order to restrict a responder to only accept
specific cipher suites, the strict flag (!, exclamation mark) can
be used, e.g: aes256-sha512-modp4096!
If dh-group is specified, CHILD_SA/Quick Mode setup and rekeying
include a separate Diffie-Hellman exchange. Valid values for
esnmode (IKEv2 only) are esn and noesn. Specifying
both negotiates Extended Sequence Number support with the peer, the
default is noesn.
- forceencaps = yes | no
- force UDP encapsulation for ESP packets even if no NAT situation is
detected. This may help to surmount restrictive firewalls. In order to
force the peer to encapsulate packets, NAT detection payloads are
faked.
- fragmentation = yes | force | no
- whether to use IKE fragmentation (proprietary IKEv1 extension). Acceptable
values are yes, force and no (the default).
Fragmented messages sent by a peer are always accepted irrespective of the
value of this option. If set to yes, and the peer supports it,
larger IKE messages will be sent in fragments. If set to force the
initial IKE message will already be fragmented if required.
- ike = <cipher suites>
- comma-separated list of IKE/ISAKMP SA encryption/authentication algorithms
to be used, e.g. aes128-sha1-modp2048. The notation is
encryption-integrity[-prf]-dhgroup. If no PRF is given, the
algorithms defined for integrity are used for the PRF. The prf keywords
are the same as the integrity algorithms, but have a prf prefix
(such as prfsha1, prfsha256 or prfaesxcbc).
In IKEv2, multiple algorithms and proposals may be included, such as
aes128-aes256-sha1-modp1536-modp2048,3des-sha1-md5-modp1024.
Defaults to aes128-sha1-modp2048,3des-sha1-modp1536. The daemon adds
its extensive default proposal to this default or the configured value. To
restrict it to the configured proposal an exclamation mark (!) can
be added at the end.
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 below.
- installpolicy = yes | no
- decides whether IPsec policies are installed in the kernel by the charon
daemon for a given connection. Allows peaceful cooperation e.g. with the
Mobile IPv6 daemon mip6d who wants to control the kernel policies.
Acceptable values are yes (the default) and no.
- keyexchange = ike | ikev1 | ikev2
- which key exchange protocol should be used to initiate the connection.
Connections marked with ike use IKEv2 when initiating, but accept
any protocol version when responding.
- keyingtries = 3 | <number> | %forever
- how many attempts (a whole number or %forever) should be made to
negotiate a connection, or a replacement for one, before giving up
(default 3). The value %forever means 'never give up'.
Relevant only locally, other end need not agree on it.
- keylife
- synonym for lifetime.
- left = <ip address> | <fqdn> | %any |
<range> | <subnet>
- The IP address of the left participant's public-network interface or one
of several magic values. The value %any (the default) for the local
endpoint signifies an address to be filled in (by automatic keying) during
negotiation. If the local peer initiates the connection setup the routing
table will be queried to determine the correct local IP address. In case
the local peer is responding to a connection setup then any IP address
that is assigned to a local interface will be accepted.
The prefix % in front of a fully-qualified domain name or an IP
address will implicitly set leftallowany=yes.
If %any is used for the remote endpoint it literally means any IP
address.
To limit the connection to a specific range of hosts, a range (
10.1.0.0-10.2.255.255 ) or a subnet ( 10.1.0.0/16 ) can be
specified, and multiple addresses, ranges and subnets can be separated by
commas. While one can freely combine these items, to initiate the
connection at least one non-range/subnet is required.
Please note that with the usage of wildcards multiple connection
descriptions might match a given incoming connection attempt. The most
specific description is used in that case.
- leftallowany = yes | no
- a modifier for left, making it behave as %any although a
concrete IP address or domain name has been assigned.
- leftauth = <auth method>
- Authentication method to use locally (left) or require from the remote
(right) side. Acceptable values are pubkey for public key
authentication (RSA/ECDSA), psk for pre-shared key authentication,
eap to (require the) use of the Extensible Authentication Protocol
in IKEv2, and xauth for IKEv1 eXtended Authentication. To require a
trustchain public key strength for the remote side, specify the key type
followed by the minimum strength in bits (for example ecdsa-384 or
rsa-2048-ecdsa-256). To limit the acceptable set of hashing
algorithms for trustchain validation, append hash algorithms to
pubkey or a key strength definition (for example
pubkey-sha1-sha256 or
rsa-2048-ecdsa-256-sha256-sha384-sha512). For eap, an
optional EAP method can be appended. Currently defined methods are
eap-aka, eap-gtc, eap-md5, eap-mschapv2,
eap-peap, eap-sim, eap-tls, eap-ttls,
eap-dynamic, and eap-radius. Alternatively, IANA assigned
EAP method numbers are accepted. Vendor specific EAP methods are defined
in the form eap-type-vendor (e.g. eap-7-12345). For
xauth, an XAuth authentication backend can be specified, such as
xauth-generic or xauth-eap. If XAuth is used in
leftauth, Hybrid authentication is used. For traditional XAuth
authentication, define XAuth in lefauth2.
- leftauth2 = <auth method>
- Same as leftauth, but defines an additional authentication
exchange. In IKEv1, only XAuth can be used in the second authentication
round. IKEv2 supports multiple complete authentication rounds using
"Multiple Authentication Exchanges" defined in RFC 4739. This
allows, for example, separated authentication of host and user.
- leftca = <issuer dn> | %same
- the distinguished name of a certificate authority which is required to lie
in the trust path going from the left participant's certificate up to the
root certification authority. %same means that the value configured
for the right participant should be reused.
- leftca2 = <issuer dn> | %same
- Same as leftca, but for the second authentication round (IKEv2
only).
- leftcert = <path>
- the path to the left participant's X.509 certificate. The file can be
encoded either in PEM or DER format. OpenPGP certificates are supported as
well. Both absolute paths or paths relative to /etc/ipsec.d/certs
are accepted. By default leftcert sets leftid to the
distinguished name of the certificate's subject. The left participant's ID
can be overridden by specifying a leftid value which must be
certified by the certificate, though.
A value in the form %smartcard[<slot
nr>[@<module>]]:<keyid> defines a specific certificate
to load from a PKCS#11 backend for this connection. See ipsec.secrets(5)
for details about smartcard definitions. leftcert is required only
if selecting the certificate with leftid is not sufficient, for
example if multiple certificates use the same subject.
Multiple certificate paths or PKCS#11 backends can be specified in a comma
separated list. The daemon chooses the certificate based on the received
certificate requests if possible before enforcing the first.
- leftcert2 = <path>
- Same as leftcert, but for the second authentication round (IKEv2
only).
- leftcertpolicy = <OIDs>
- Comma separated list of certificate policy OIDs the peer's certificate
must have. OIDs are specified using the numerical dotted
representation.
- leftdns = <servers>
- Comma separated list of DNS server addresses to exchange as configuration
attributes. On the initiator, a server is a fixed IPv4/IPv6 address, or
%config4/%config6 to request attributes without an address.
On the responder, only fixed IPv4/IPv6 addresses are allowed and define
DNS servers assigned to the client.
- leftfirewall = yes | no
- whether the left participant is doing forwarding-firewalling (including
masquerading) using iptables for traffic from leftsubnet, which
should be turned off (for traffic to the other subnet) once the connection
is established; acceptable values are yes and no (the
default). May not be used in the same connection description with
leftupdown. Implemented as a parameter to the default ipsec
_updown script. See notes below. Relevant only locally, other end need
not agree on it.
If one or both security gateways are doing forwarding firewalling (possibly
including masquerading), and this is specified using the firewall
parameters, tunnels established with IPsec are exempted from it so that
packets can flow unchanged through the tunnels. (This means that all
subnets connected in this manner must have distinct, non-overlapping
subnet address blocks.) This is done by the default ipsec _updown
script.
In situations calling for more control, it may be preferable for the user to
supply his own updown script, which makes the appropriate
adjustments for his system.
- leftgroups = <group list>
- a comma separated list of group names. If the leftgroups parameter
is present then the peer must be a member of at least one of the groups
defined by the parameter.
- leftgroups2 = <group list>
- Same as leftgroups, but for the second authentication round defined
with leftauth2.
- lefthostaccess = yes | no
- inserts a pair of INPUT and OUTPUT iptables rules using the default
ipsec _updown script, thus allowing access to the host itself in
the case where the host's internal interface is part of the negotiated
client subnet. Acceptable values are yes and no (the
default).
- leftid = <id>
- how the left participant should be identified for authentication; defaults
to left or the subject of the certificate configured with
leftcert. Can be an IP address, a fully-qualified domain name, an
email address, or a keyid. If leftcert is configured the identity
has to be confirmed by the certificate.
For IKEv2 and rightid the prefix % in front of the identity
prevents the daemon from sending IDr in its IKE_AUTH request and will
allow it to verify the configured identity against the subject and
subjectAltNames contained in the responder's certificate (otherwise it is
only compared with the IDr returned by the responder). The IDr sent by the
initiator might otherwise prevent the responder from finding a config if
it has configured a different value for leftid.
- leftid2 = <id>
- identity to use for a second authentication for the left participant
(IKEv2 only); defaults to leftid.
- leftikeport = <port>
- UDP port the left participant uses for IKE communication. If unspecified,
port 500 is used with the port floating to 4500 if a NAT is detected or
MOBIKE is enabled. Specifying a local IKE port different from the default
additionally requires a socket implementation that listens on this
port.
- leftprotoport = <protocol>/<port>
- restrict the traffic selector to a single protocol and/or port. This
option is now deprecated, protocol/port information can be defined for
each subnet directly in leftsubnet.
- leftsigkey = <raw public key> | <path to public
key>
- the left participant's public key for public key signature authentication,
in PKCS#1 format using hex (0x prefix) or base64 (0s prefix) encoding.
With the optional dns: or ssh: prefix in front of 0x or 0s,
the public key is expected to be in either the RFC 3110 (not the full RR,
only RSA key part) or RFC 4253 public key format, respectively. Also
accepted is the path to a file containing the public key in PEM, 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 certificate request payload in order to get a certificate
in return.
- leftsourceip = %config4 | %config6 | <ip address>
- Comma separated list of internal source IPs to use in a tunnel, also known
as virtual IP. If the value is one of the synonyms %config,
%cfg, %modeconfig, or %modecfg, an address (from the
tunnel address family) is requested from the peer. With %config4
and %config6 an address of the given address family will be
requested explicitly. If an IP address is configured, it will be requested
from the responder, which is free to respond with a different
address.
- rightsourceip = %config | <network>/<netmask> |
%poolname
- Comma separated list of internal source IPs to use in a tunnel for the
remote peer. If the value is %config on the responder side, the
initiator must propose an address which is then echoed back. Also
supported are address pools expressed as
network/netmask or the use of an external IP address
pool using % poolname, where poolname is the name of the IP
address pool used for the lookup.
- leftsubnet = <ip subnet>[[<proto/port>]][,...]
- private subnet behind the left participant, expressed as
network/ netmask; if omitted, essentially assumed to
be left/32, signifying that the left end of the connection
goes to the left participant only. Configured subnets of the peers may
differ, the protocol narrows it to the greatest common subnet. In IKEv1,
this may lead to problems with other implementations, make sure to
configure identical subnets in such configurations. IKEv2 supports
multiple subnets separated by commas. IKEv1 only interprets the first
subnet of such a definition, unless the Cisco Unity extension plugin is
enabled.
The optional part after each subnet enclosed in square brackets specifies a
protocol/port to restrict the selector for that subnet.
Examples: leftsubnet=10.0.0.1[tcp/http],10.0.0.2[6/80] or
leftsubnet=fec1::1[udp],10.0.0.0/16[/53]. Instead of omitting
either value %any can be used to the same effect, e.g.
leftsubnet=fec1::1[udp/%any],10.0.0.0/16[%any/53].
If the protocol is icmp or ipv6-icmp the port is interpreted
as ICMP message type if it is less than 256 or as type and code if it is
greater or equal to 256, with the type in the most significant 8 bits and
the code in the least significant 8 bits.
The port value can alternatively take the value %opaque for RFC 4301
OPAQUE selectors, or a numerical range in the form 1024-65535. None
of the kernel backends currently supports opaque or port ranges and uses
%any for policy installation instead.
Instead of specifying a subnet, %dynamic can be used to replace it
with the IKE address, having the same effect as omitting leftsubnet
completely. Using %dynamic can be used to define multiple dynamic
selectors, each having a potentially different protocol/port definition.
- leftupdown = <path>
- what ``updown'' script to run to adjust routing and/or firewalling when
the status of the connection changes (default ipsec _updown). May
include positional parameters separated by white space (although this
requires enclosing the whole string in quotes); including shell
metacharacters is unwise. Relevant only locally, other end need not agree
on it. Charon uses the updown script to insert firewall rules only, since
routing has been implemented directly into the daemon.
- lifebytes = <number>
- the number of bytes transmitted over an IPsec SA before it expires.
- lifepackets = <number>
- the number of packets transmitted over an IPsec SA before it expires.
- lifetime = 1h | <time>
- how long a particular instance of a connection (a set of
encryption/authentication keys for user packets) should last, from
successful negotiation to expiry; acceptable values are an integer
optionally followed by s (a time in seconds) or a decimal number
followed by m, h, or d (a time in minutes, hours, or
days respectively) (default 1h, maximum 24h). Normally, the
connection is renegotiated (via the keying channel) before it expires (see
margintime). The two ends need not exactly agree on
lifetime, although if they do not, there will be some clutter of
superseded connections on the end which thinks the lifetime is longer.
Also see EXPIRY/REKEY below.
- marginbytes = <number>
- how many bytes before IPsec SA expiry (see lifebytes) should
attempts to negotiate a replacement begin.
- marginpackets = <number>
- how many packets before IPsec SA expiry (see lifepackets) should
attempts to negotiate a replacement begin.
- margintime = 9m | <time>
- how long before connection expiry or keying-channel expiry should attempts
to negotiate a replacement begin; acceptable values as for lifetime
(default 9m). Relevant only locally, other end need not agree on
it. Also see EXPIRY/REKEY below.
- mark = <value>[/<mask>]
- sets an XFRM mark in the inbound and outbound IPsec SAs and policies. If
the mask is missing then a default mask of 0xffffffff is
assumed.
- mark_in = <value>[/<mask>]
- sets an XFRM mark in the inbound IPsec SA and policy. If the mask is
missing then a default mask of 0xffffffff is assumed.
- mark_out = <value>[/<mask>]
- sets an XFRM mark in the outbound IPsec SA and policy. If the mask is
missing then a default mask of 0xffffffff is assumed.
- mobike = yes | no
- enables the IKEv2 MOBIKE protocol defined by RFC 4555. Accepted values are
yes (the default) and no. If set to no, the charon
daemon will not actively propose MOBIKE as initiator and ignore the
MOBIKE_SUPPORTED notify as responder.
- modeconfig = push | pull
- defines which mode is used to assign a virtual IP. Accepted values are
push and pull (the default). Push mode is currently not
supported with IKEv2.
- reauth = yes | no
- whether rekeying of an IKE_SA should also reauthenticate the peer. In
IKEv1, reauthentication is always done. In IKEv2, a value of no
rekeys without uninstalling the IPsec SAs, a value of yes (the
default) creates a new IKE_SA from scratch and tries to recreate all IPsec
SAs.
- rekey = yes | no
- whether a connection should be renegotiated when it is about to expire;
acceptable values are yes (the default) and no. The two ends
need not agree, but while a value of no prevents charon from
requesting renegotiation, it does not prevent responding to renegotiation
requested from the other end, so no will be largely ineffective
unless both ends agree on it. Also see reauth.
- rekeyfuzz = 100% | <percentage>
- maximum percentage by which marginbytes, marginpackets and
margintime should be randomly increased to randomize rekeying
intervals (important for hosts with many connections); acceptable values
are an integer, which may exceed 100, followed by a `%' (defaults to
100%). The value of marginTYPE, after this random increase,
must not exceed lifeTYPE (where TYPE is one of bytes,
packets or time). The value 0% will suppress
randomization. Relevant only locally, other end need not agree on it. Also
see EXPIRY/REKEY below.
- rekeymargin
- synonym for margintime.
- 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 Confidentiality
is currently supported in IKEv2 and applies to outgoing packets only. The
special value %mtu fills up ESP packets with padding to have the
size of the MTU.
- type = tunnel | transport | transport_proxy | passthrough |
drop
- the type of the connection; currently the accepted values are
tunnel (the default) signifying a host-to-host, host-to-subnet, or
subnet-to-subnet tunnel; transport, signifying host-to-host
transport mode; transport_proxy, signifying the special Mobile IPv6
transport proxy mode; passthrough, signifying that no IPsec
processing should be done at all; drop, signifying that packets
should be discarded.
- xauth = client | server
- specifies the role in the XAuth protocol if activated by
authby=xauthpsk or authby=xauthrsasig. Accepted values are
server and client (the default).
- xauth_identity = <id>
- defines the identity/username the client uses to reply to an XAuth
request. If not defined, the IKEv1 identity will be used as XAuth
identity.
The following parameters are relevant to IKEv2 Mediation Extension operation
only.
- mediation = yes | no
- whether this connection is a mediation connection, ie. whether this
connection is used to mediate other connections. Mediation connections
create no child SA. Acceptable values are no (the default) and
yes.
- mediated_by = <name>
- the name of the connection to mediate this connection through. If given,
the connection will be mediated through the named mediation connection.
The mediation connection must set mediation=yes.
- me_peerid = <id>
- ID as which the peer is known to the mediation server, ie. which the other
end of this connection uses as its leftid on its connection to the
mediation server. This is the ID we request the mediation server to
mediate us with. If me_peerid is not given, the rightid of
this connection will be used as peer ID.
CA SECTIONS¶
These are optional sections that can be used to assign special parameters to a
Certification Authority (CA). Because the daemons automatically import CA
certificates from
/etc/ipsec.d/cacerts, there is no need to explicitly
add them with a CA section, unless you want to assign special parameters (like
a CRL) to a CA.
- also = <name>
- includes ca section <name>.
- auto = ignore | add
- currently can have either the value ignore (the default) or
add.
- cacert = <path>
- defines a path to the CA certificate either relative to
/etc/ipsec.d/cacerts or as an absolute path.
A value in the form %smartcard[<slot
nr>[@<module>]]:<keyid> defines a specific CA
certificate to load from a PKCS#11 backend for this CA. See
ipsec.secrets(5) for details about smartcard definitions.
- crluri = <uri>
- defines a CRL distribution point (ldap, http, or file URI)
- crluri1
- synonym for crluri.
- crluri2 = <uri>
- defines an alternative CRL distribution point (ldap, http, or file
URI)
- ocspuri = <uri>
- defines an OCSP URI.
- ocspuri1
- synonym for ocspuri.
- ocspuri2 = <uri>
- defines an alternative OCSP URI.
- certuribase = <uri>
- defines the base URI for the Hash and URL feature supported by IKEv2.
Instead of exchanging complete certificates, IKEv2 allows one to send an
URI that resolves to the DER encoded certificate. The certificate URIs are
built by appending the SHA1 hash of the DER encoded certificates to this
base URI.
CONFIG SECTIONS¶
At present, the only
config section known to the IPsec software is the
one named
setup, which contains information used when the software is
being started. The currently-accepted
parameter names in a
config setup section are:
- cachecrls = yes | no
- if enabled, certificate revocation lists (CRLs) fetched via HTTP or LDAP
will be cached in /etc/ipsec.d/crls/ under a unique file name
derived from the certification authority's public key.
- charondebug = <debug list>
- how much charon debugging output should be logged. A comma separated list
containing type/level-pairs may be specified, e.g: dmn 3, ike 1, net
-1. Acceptable values for types are dmn, mgr, ike, chd, job, cfg,
knl, net, asn, enc, lib, esp, tls, tnc, imc, imv, pts and the
level is one of -1, 0, 1, 2, 3, 4 (for silent, audit, control,
controlmore, raw, private). By default, the level is set to 1 for
all types. For more flexibility see LOGGER CONFIGURATION in
strongswan.conf(5).
- strictcrlpolicy = yes | ifuri | no
- defines if a fresh CRL must be available in order for the peer
authentication based on RSA signatures to succeed. IKEv2 additionally
recognizes ifuri which reverts to yes if at least one CRL
URI is defined and to no if no URI is known.
- uniqueids = yes | no | never | replace | keep
- whether a particular participant ID should be kept unique, with any new
IKE_SA using an ID deemed to replace all old ones using that ID;
acceptable values are yes (the default), no and
never. Participant IDs normally are unique, so a new IKE_SA
using the same ID is almost invariably intended to replace an old one. The
difference between no and never is that the daemon will
replace old IKE_SAs when receiving an INITIAL_CONTACT notify if the option
is no but will ignore these notifies if never is configured.
The daemon also accepts the value replace which is identical to
yes and the value keep to reject new IKE_SA setups and keep
the duplicate established earlier.
SA EXPIRY/REKEY¶
The IKE SAs and IPsec SAs negotiated by the daemon can be configured to expire
after a specific amount of time. For IPsec SAs this can also happen after a
specified number of transmitted packets or transmitted bytes. The following
settings can be used to configure this:
Setting |
Default |
Setting |
Default |
|
|
|
|
IKE SA |
|
IPsec SA |
|
ikelifetime |
3h |
lifebytes |
- |
|
|
lifepackets |
- |
|
|
lifetime |
1h |
Rekeying¶
IKE SAs as well as IPsec SAs can be rekeyed before they expire. This can be
configured using the following settings:
Setting |
Default |
Setting |
Default |
|
|
|
|
IKE and IPsec SA |
|
IPsec SA |
|
margintime |
9m |
marginbytes |
- |
|
|
marginpackets |
- |
Randomization¶
To avoid collisions the specified margins are increased randomly before
subtracting them from the expiration limits (see formula below). This is
controlled by the
rekeyfuzz setting:
Setting |
Default |
|
|
IKE and IPsec SA |
|
rekeyfuzz |
100% |
Randomization can be disabled by setting
rekeyfuzz to
0%.
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)
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.