IPSEC.CONF(5) [FIXME: manual] IPSEC.CONF(5)NAMEipsec.conf - IPsec configuration and connections
DESCRIPTION
The optional ipsec.conf file specifies most configuration and control
information for the Openswan IPsec subsystem. (The major exception is
secrets for authentication; see ipsec.secrets(5).) Its contents are not
security-sensitive unless manual keying is being done for more than
just testing, in which case the encryption/authentication keys in the
descriptions for the manually-keyed connections are very sensitive (and
those connection descriptions are probably best kept in a separate
file, via the include facility described below).
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 and alsoflip
parameters (described below) which permit splitting a single logical
section (e.g. a connection description) into several actual sections.
The first significant line of the file must specify the version of this
specification that it conforms to:
version 2
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.) This allows,
for example, keeping the encryption keys for a connection in a
separate file from the rest of the description, by using both an
also parameter and an include line. (Caution, see BUGS below for
some restrictions.)
alsoflip
can be used in a conn section. It acts like an also that flips the
referenced section's entries left-for-right.
Parameter names beginning with x- (or X-, or x_, or X_) are reserved
for user extensions and will never be assigned meanings by IPsec.
Parameters with such names must still observe the syntax rules (limits
on characters used in the name; no white space in a non-quoted value;
no newlines or double quotes within the value). All other as-yet-unused
parameter names are reserved for future IPsec improvements.
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 also or alsoflip parameters.
Currently there are two types of section: a config section specifies
general configuration information for IPsec, while a conn section
specifies an IPsec connection.
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 to ipsec_auto(8) and ipsec_manual(8).
Here's a simple example:
conn snt
left=10.11.11.1
leftsubnet=10.0.1.0/24
leftnexthop=172.16.55.66
leftsourceip=10.0.1.1
right=192.168.22.1
rightsubnet=10.0.2.0/24
rightnexthop=172.16.88.99
rightsourceip=10.0.2.1
keyingtries=%forever
A note on terminology... In automatic keying, 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 data path (a set of “IPsec SAs”) used for user packets is
herein referred to as the “connection”; the path used for negotiations
(built with “ISAKMP SAs”) is referred to as the “keying channel”.
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;
IPsec figures out which one it is being run on based on internal
information. 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)”; a parameter
required for manual keying need not be included for a connection which
will use only automatic keying, and vice versa.
CONN PARAMETERS: GENERAL
The following parameters are relevant to both automatic and manual
keying. 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.
connaddrfamily
the connection addrress family of the connection; currently the
accepted values are ipv4 (the default); or ipv6. This option is
confusing, especially when doing IPv4-in-IPv6 or IPv6-in-IPv4
tunnels. The developers hope to remove this option in the near
future for proper auto-detection. For now, set connaddrfamily= to
the family of the *subnet= options, and if those are not defined,
to the family of the left=/right= options.
IPv6 is supported with NETKEY since openswan 2.4 and with KLIPS
since Openswan 2.6.33
type
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; 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.
left
(required) the IP address of the left participant's public-network
interface, in any form accepted by ipsec_ttoaddr(3). Currently,
IPv4 and IPv6 IP addresses are supported. There are several magic
values. If it is %defaultroute, and the config setup section's,
interfaces specification contains %defaultroute, left will be
filled in automatically with the local address of the default-route
interface (as determined at IPsec startup time); this also
overrides any value supplied for leftnexthop. (Either left or right
may be %defaultroute, but not both.) The value %any signifies an
address to be filled in (by automatic keying) during negotiation.
The value %opportunistic signifies that both left and leftnexthop
are to be filled in (by automatic keying) from DNS data for left's
client. The value can also contain the interface name, which will
then later be used to obtain the IP address from to fill in. For
example %ppp0 The values %group and %opportunisticgroup makes this
a policy group conn: one that will be instantiated into a regular
or opportunistic conn for each CIDR block listed in the policy
group file with the same name as the conn.
If using IP addresses in combination with NAT, always use the
actual local machine's (NAT'ed) IP address, and if the remote (eg
right=) is NAT'ed as well, the remote's public (not NAT'ed) IP
address. Note that this makes the configuration no longer
symmetrical on both sides, so you cannot use an identical
configuration file on both hosts.
leftsubnet
private subnet behind the left participant, expressed as
network/netmask (actually, any form acceptable to
ipsec_ttosubnet(3)); Currentlly, IPv4 and IPv6 ranges are
supported. if omitted, essentially assumed to be left/32,
signifying that the left end of the connection goes to the left
participant only
It supports two magic shorthands vhost: and vnet:, which can list
subnets in the same syntax as virtual_private. The value %priv
expands to the networks specified in virtual_private. The value %no
means no subnet. A common use for allowing roadwarrios to come in
on public IPs or via accepted NATed networks from RFC1918 is to use
leftsubnet=vhost:%no,%priv. The vnet: option can be used to allow
RFC1918 subnets without hardcoding them. When using vnet the
connection will instantiate, allowing for multiple tunnels with
different subnets.
leftsubnets
specify multiple private subnets behind the left participant,
expressed as { networkA/netmaskA networkB/netmaskB [...] } If both
a leftsubnets= and rightsubnets= is defined, all combinations of
subnet tunnels will be instantiated. You cannot use leftsubnet and
leftsubnets together. For examples see testing/pluto/multinet-*.
leftprotoport
allowed protocols and ports over connection, also called Port
Selectors. The argument is in the form protocol, which can be a
number or a name that will be looked up in /etc/protocols, such as
leftprotoport=icmp, or in the form of protocol/port, such as
tcp/smtp. Ports can be defined as a number (eg. 25) or as a name
(eg smtp) which will be looked up in /etc/services. A special
keyword %any can be used to allow all ports of a certain protocol.
The most common use of this option is for L2TP connections to only
allow l2tp packets (UDP port 1701), eg: leftprotoport=17/1701. Some
clients, notably older Windows XP and some Mac OSX clients, use a
random high port as source port. In those cases
rightprotoport=17/%any can be used to allow all UDP traffic on the
connection. Note that this option is part of the proposal, so it
cannot be arbitrarily left out if one end does not care about the
traffic selection over this connection - both peers have to agree.
The Port Selectors show up in the output of ipsec eroute and ipsec
auto --status eg:"l2tp":
193.110.157.131[@aivd.xelernace.com]:7/1701...%any:17/1701 This
option only filters outbound traffic. Inbound traffic selection
must still be based on firewall rules activated by an updown
script. The variablees $PLUTO_MY_PROTOCOL, $PLUTO_PEER_PROTOCOL,
$PLUTO_MY_PORT, and $PLUTO_PEER_PORT are available for use in
updown scripts. Older workarounds for bugs involved a setting of
17/0 to denote any single UDP port (not UDP port 0). Some clients,
most notably OSX, uses a random high port, instead of port 1701 for
L2TP.
leftnexthop
next-hop gateway IP address for the left participant's connection
to the public network; defaults to %direct (meaning right). If the
value is to be overridden by the left=%defaultroute method (see
above), an explicit value must not be given. If that method is not
being used, but leftnexthop is %defaultroute, and
interfaces=%defaultroute is used in the config setup section, the
next-hop gateway address of the default-route interface will be
used. The magic value %direct signifies a value to be filled in (by
automatic keying) with the peer's address. Relevant only locally,
other end need not agree on it.
leftsourceip
the IP address for this host to use when transmitting a packet to
the other side of this link. Relevant only locally, the other end
need not agree. This option is used to make the gateway itself use
its internal IP, which is part of the leftsubnet, to communicate to
the rightsubnet or right. Otherwise, it will use its nearest IP
address, which is its public IP address. This option is mostly used
when defining subnet-subnet connections, so that the gateways can
talk to each other and the subnet at the other end, without the
need to build additional host-subnet, subnet-host and host-host
tunnels. Both IPv4 and IPv6 addresses are supported.
leftupdown
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. An example to enable
routing when using the NETKEY stack, one can use:
leftupdown="ipsec _updown --route yes"
See ipsec_pluto(8) for details. Relevant only locally, other end
need not agree on it.
leftfirewall
This option is obsolete and should not used anymore.
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
updown script (see ipsec_pluto(8)).
The implementation of this makes certain assumptions about firewall
setup, and the availability of the Linux Advanced Routing tools. 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.
CONN PARAMETERS: AUTOMATIC KEYING
The following parameters are relevant only to automatic keying, and are
ignored in manual keying. 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.
auto
what operation, if any, should be done automatically at IPsec
startup; currently-accepted values are add (signifying an ipsec
auto --add), route (signifying that plus an ipsec auto --route),
start (signifying that plus an ipsec auto --up), manual (signifying
an ipsec manual --up), and ignore (also the default) (signifying no
automatic startup operation). See the config setup discussion
below. 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).
authby
how the two security gateways should authenticate each other;
acceptable values are secret for shared secrets, rsasig for RSA
digital signatures (the default), secret|rsasig for either, and
never if negotiation is never to be attempted or accepted (useful
for shunt-only conns). Digital signatures are superior in every way
to shared secrets.
ike
IKE encryption/authentication algorithm to be used for the
connection (phase 1 aka ISAKMP SA). The format is
"cipher-hash;modpgroup, cipher-hash;modpgroup, ..." Any left out
option will be filled in with all allowed default options. Multiple
proposals are separated by a comma. If an ike= line is specified,
no other received proposals will be accepted. Formerly there was a
distinction (by using a "!" symbol) between "strict mode" or not.
That mode has been obsoleted. If an ike= option is specified, the
mode is always strict, meaning no other received proposals will be
accepted. Some examples are ike=3des-sha1,aes-sha1, ike=aes,
ike=aes128-md5;modp2048, ike=aes128-sha1;dh22,
ike=3des-md5;modp1024,aes-sha1;modp1536 or ike=modp1536. The
options must be suitable as a value of ipsec_spi(8)'s --ike option.
The default is to use IKE, and to allow all combinations of:
cipher: 3des or aes
hash: sha1 or md5
pfsgroup (DHgroup): modp1024 or modp1536
If Openswan was compiled with extra INSECURE and BROKEN options,
then the des (1des) and null cipher, as well as modp768 are
available. This turns your VPN into a joke. Do not enable these
options.
If openswan was compiled with USE_MODP_RFC5114 support, then
Diffie-Hellman groups 22, 23 and 24 are also implemented as per
RFC-5114. Instead of the modp key syntax, use the "dh" keyword, for
example ike=3des-sha1;dh23
phase2
Sets the type of SA that will be produced. Valid options are: esp
for encryption (the default), and ah for authentication only.
phase2alg
Specifies the algorithms that will be offered/accepted for a phase2
negotiation. If not specified, a secure set of defaults will be
used. Sets are separated using comma's.
The default values are the same as for ike= Note also that not all
ciphers available to the kernel (eg through CryptoAPI) are
necessarilly supported here.
The format for ESP is ENC-AUTH followed by an optional PFSgroup.
For instance, "3des-md5" or "aes256-sha1;modp2048" or
"aes-sha1,aes-md5".
For RFC-5114 DH groups, use the "dh" keyword, eg "aes256-sha1;dh23"
The format for AH is AUTH followed by an optional PFSgroup. For
instance, "md5" or "sha1;modp1536".
A special case is AES CCM, which uses the syntax of
"phase2alg=aes_ccm_a-152-null"
esp
This option is obsolete. Please use phase2alg instead.
ah
AH authentication algorithm to be used for the connection, e.g
here. hmac-md5 The options must be suitable as a value of
ipsec_spi(8)'s --ah option. The default is not to use AH. If for
some (invalid) reason you still think you need AH, please use esp
with the null encryption cipher instead. Note also that not all
ciphers available to the kernel (eg through CryptoAPI) are
necessarilly supported here.
ikev2
IKEv2 (RFC4309) settings to be used. Currently the accepted values
are permit, (the default) signifying no IKEv2 should be
transmitted, but will be accepted if the other ends initiates to us
with IKEv2; never or no signifying no IKEv2 negotiation should be
transmitted or accepted; propose or yes signifying that we permit
IKEv2, and also use it as the default to initiate; insist,
signifying we only accept and receive IKEv2 - IKEv1 negotiations
will be rejected.
If the ikev2= setting is set to permit or propose, Openswan will
try and detect a "bid down" attack from IKEv2 to IKEv1. Since there
is no standard for transmitting the IKEv2 capability with IKEv1,
Openswan uses a special Vendor ID "CAN-IKEv2". If a fall back from
IKEv2 to IKEv1 was detected, and the IKEv1 negotiation contains
Vendor ID "CAN-IKEv2", Openswan will immediately attempt and IKEv2
rekey and refuse to use the IKEv1 connection. With an ikev2=
setting of insist, no IKEv1 negotiation is allowed, and no bid down
attack is possible.
sareftrack
Set the method of tracking reply packets with SArefs when using an
SAref compatible stack. Currently only the mast stack supports
this. Acceptable values are yes (the default), no or conntrack.
This option is ignored when SArefs are not supported. This option
is passed as PLUTO_SAREF_TRACKING to the updown script which makes
the actual decisions whether to perform any iptables/ip_conntrack
manipulation. A value of yes means that an IPSEC mangle table will
be created. This table will be used to match reply packets. A value
of conntrack means that additionally, subsequent packets using this
connection will be marked as well, reducing the lookups needed to
find the proper SAref by using the ip_conntrack state. A value of
no means no IPSEC mangle table is created, and SAref tracking is
left to a third-party (kernel) module. In case of a third party
module, the SArefs can be relayed using the HAVE_STATSD deamon.
leftid
how the left participant should be identified for authentication;
defaults to left. Can be an IP address (in any ipsec_ttoaddr(3)
syntax) or a fully-qualified domain name preceded by @ (which is
used as a literal string and not resolved). The magic value
%fromcert causes the ID to be set to a DN taken from a certificate
that is loaded. Prior to 2.5.16, this was the default if a
certificate was specified. The magic value %none sets the ID to no
ID. This is included for completeness, as the ID may have been set
in the default conn, and one wishes for it to default instead of
being explicitly set. The magic value %myid stands for the current
setting of myid. This is set in config setup or by ipsec_whack(8)),
or, if not set, it is the IP address in %defaultroute (if that is
supported by a TXT record in its reverse domain), or otherwise it
is the system's hostname (if that is supported by a TXT record in
its forward domain), or otherwise it is undefined.
leftrsasigkey
the left participant's public key for RSA signature authentication,
in RFC 2537 format using ipsec_ttodata(3) encoding. The magic value
%none means the same as not specifying a value (useful to override
a default). The value %dnsondemand (the default) means the key is
to be fetched from DNS at the time it is needed. The value
%dnsonload means the key is to be fetched from DNS at the time the
connection description is read from ipsec.conf; currently this will
be treated as %none if right=%any or right=%opportunistic. The
value %dns is currently treated as %dnsonload but will change to
%dnsondemand in the future. The identity used for the left
participant must be a specific host, not %any or another magic
value. The value %cert will load the information required from a
certificate defined in %leftcert and automatically define leftid
for you. Caution: if two connection descriptions specify different
public keys for the same leftid, confusion and madness will ensue.
leftrsasigkey2
if present, a second public key. Either key can authenticate the
signature, allowing for key rollover.
leftcert
If you are using leftrsasigkey=%cert this defines the certificate
you would like to use. It should point to a X.509 encoded
certificate file. If you do not specify a full pathname, by default
it will look in /etc/ipsec.d/certs. If openswan has been compiled
with USE_LIBNSS=true, then openswan will also check the NSS
database for RSA keys. These can be software or hardware.
leftca
specifies the authorized Certificate Authority (CA) that signed the
certificate of the peer. If undefined, it defaults to the CA that
signed the certificate specified in leftcert. The special
rightca=%same is implied when not specifying a rightca and means
that only peers with certificates signed by the same CA as the
leftca will be allowed. This option is only useful in complex multi
CA certificate situations. When using a single CA, it can be safely
omitted for both left and right.
leftsendcert
This option configures when Openswan will send X.509 certificates
to the remote host. Acceptable values are yes|always (signifying
that we should always send a certificate), ifasked (signifying that
we should send a certificate if the remote end asks for it), and
no|never (signifying that we will never send a X.509 certificate).
The default for this option is ifasked which may break
compatibility with other vendor's IPSec implementations, such as
Cisco and SafeNet. If you find that you are getting errors about no
ID/Key found, you likely need to set this to always. This per-conn
option replaces the obsolete global nocrsend option.
leftxauthserver
Left is an XAUTH server. This can use PAM for authentication or md5
passwords in /etc/ipsec.d/passwd. These are additional credentials
to verify the user identity, and should not be confused with the
XAUTH group secret, which is just a regular PSK defined in
ipsec.secrets. The other side of the connection should be
configured as rightxauthclient. XAUTH connections cannot rekey, so
rekey=no should be specified in this conn. For further details on
how to compile and use XAUTH, see README.XAUTH. Acceptable values
are yes or no (the default).
leftxauthclient
Left is an XAUTH client. The xauth connection will have to be
started interactively and cannot be configured using auto=start.
Instead, it has to be started from the commandline using ipsec auto
--up connname. You will then be prompted for the username and
password. To setup an XAUTH connection non-interactively, which
defeats the whole purpose of XAUTH, but is regularly requested by
users, it is possible to use a whack command - ipsec whack --name
baduser --ipsecgroup-xauth --xauthname badusername --xauthpass
password --initiate The other side of the connection should be
configured as rightxauthserver. Acceptable values are yes or no
(the default).
leftxauthusername
The XAUTH username associated with this XAUTH connection. The XAUTH
password can be configured in the ipsec.secrets file.
leftmodecfgserver
Left is a Mode Config server. It can push network configuration to
the client. Acceptable values are yes or no (the default).
leftmodecfgclient
Left is a Mode Config client. It can receive network configuration
from the server. Acceptable values are yes or no (the default).
modecfgpull
Pull the Mode Config network information from the server.
Acceptable values are yes or no (the default).
modecfgdns1, modecfgdns2, modecfgwins1, modecfgwins2
Specify the IP address for DNS or WINS servers for the client to
use.
remote_peer_type
Set the remote peer type. This can enable additional processing
during the IKE negotiation. Acceptable values are cisco or ietf
(the default). When set to cisco, support for Cisco IPsec gateway
redirection and Cisco obtained DNS and domainname are enabled. This
includes automatically updating (and restoring) /etc/resolv.conf.
These options require that XAUTH is also enabled on this
connection.
nm_configured
Mark this connection as controlled by Network Manager. Acceptable
values are yes or no (the default). Currently, setting this to yes
will cause openswan to skip reconfiguring resolv.conf when used
with XAUTH and ModeConfig.
forceencaps
In some cases, for example when ESP packets are filtered or when a
broken IPsec peer does not properly recognise NAT, it can be useful
to force RFC-3948 encapsulation. forceencaps=yes forces the NAT
detection code to lie and tell the remote peer that RFC-3948
encapsulation (ESP in UDP port 4500 packets) is required. For this
option to have any effect, the setup section option
nat_traversal=yes needs to be set. Acceptable values are yes or no
(the default).
overlapip
a boolean (yes/no) that determines, when *subnet=vhost: is used, if
the virtual IP claimed by this states created from this connection
can with states created from other connections.
Note that connection instances created by the Opportunistic
Encryption or PKIX (x.509) instantiation system are distinct
internally. They will inherit this policy bit.
The default is no.
This feature is only available with kernel drivers that support SAs
to overlapping conns. At present only the (klips)mast protocol
stack supports this feature.
dpddelay
Set the delay (in seconds) between Dead Peer Dectection (RFC 3706)
keepalives (R_U_THERE, R_U_THERE_ACK) that are sent for this
connection (default 30 seconds). If dpddelay is set, dpdtimeout
also needs to be set.
dpdtimeout
Set the length of time (in seconds) we will idle without hearing
either an R_U_THERE poll from our peer, or an R_U_THERE_ACK reply.
After this period has elapsed with no response and no traffic, we
will declare the peer dead, and remove the SA (default 120
seconds). If dpdtimeout is set, dpdaction also needs to be set.
dpdaction
When a DPD enabled peer is declared dead, what action should be
taken. hold (default) means the eroute will be put into %hold
status, while clear means the eroute and SA with both be cleared.
restart means the the SA will immediately be renegotiated, and
restart_by_peer means that ALL SA's to the dead peer will
renegotiated.
dpdaction=clear is really only useful on the server of a Road
Warrior config.
pfs
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);
Since there is no reason to ever refuse PFS, Openswan will allow a
connection defined with pfs=no to use PFS anyway. Acceptable values
are yes (the default) and no.
pfsgroup
This option is obsoleted, please use phase2alg if you need the pfs
to be different from phase1 (the default) using:
phase2alg=aes128-md5;modp1024
aggrmode
Use Aggressive Mode instead of Main Mode. Aggressive Mode is less
secure, and vulnerable to Denial Of Service attacks. It is also
vulnerable to brute force attacks with software such as ikecrack.
It should not be used, and it should especially not be used with
XAUTH and group secrets (PSK). If the remote system administrator
insists on staying irresponsible, enable this option.
Aggressive Mode is further limited to only proposals with one DH
group as there is no room to negotiate the DH group. Therefor it is
mandatory for Aggressive Mode connections that both ike= and
phase2alg= options are specified with only fully specified proposal
using one DH group. Acceptable values are yes or no (the default).
The ISAKMP SA is created in exchange 1 in aggressive mode. Openswan
has to send the exponent during that exchange, so it has to know
what DH group to use before starting. This is why you can not have
multiple DH groups in aggressive mode. In IKEv2, which uses a
similar method to IKEv1 Aggressive Mode, there is a message to
convey the DH group is wrong, and so an IKEv2 connection can
actually recover from picking the wrong DH group by restarting its
negotiation.
salifetime
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 8h, maximum 24h). Normally, the connection
is renegotiated (via the keying channel) before it expires. The two
ends need not exactly agree on salifetime, although if they do not,
there will be some clutter of superseded connections on the end
which thinks the lifetime is longer.
The keywords "keylife" and "lifetime" are aliases for "salifetime."
rekey
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 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.
rekeymargin
how long before connection expiry or keying-channel expiry should
attempts to negotiate a replacement begin; acceptable values as for
salifetime (default 9m). Relevant only locally, other end need not
agree on it.
rekeyfuzz
maximum percentage by which rekeymargin 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 `%' (default set by ipsec_pluto(8),
currently 100%). The value of rekeymargin, after this random
increase, must not exceed salifetime. The value 0% will suppress
time randomization. Relevant only locally, other end need not agree
on it.
keyingtries
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”
(obsolete: this can be written 0). Relevant only locally, other end
need not agree on it.
ikelifetime
how long the keying channel of a connection (buzzphrase: “ISAKMP
SA”) should last before being renegotiated; acceptable values as
for keylife (default set by ipsec_pluto(8), currently 1h, maximum
24h). The two-ends-disagree case is similar to that of keylife.
compress
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). The two ends need not agree. 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.
metric
Set the metric for the routes to the ipsecX or mastX interface.
This makes it possible to do host failover from another interface
to ipsec using route management. This value is passed to the
_updown scripts as PLUTO_METRIC. This option is only available with
KLIPS or MAST on Linux. Acceptable values are positive numbers,
with the default being 1.
mtu
Set the mtu for the route(s) to the remote endpoint and/or subnets.
This is sometimes required when the overhead of the IPsec
encapsultion would cause the packet the become too big for a router
on the path. Since IPsec cannot trust any unauthenticated ICMP
messages, PATH MTU discovery does not work. This can also be needed
when using "6to4" IPV6 deployments, which adds another header on
the packet size. Acceptable values are positive numbers. There is
no default.
disablearrivalcheck
whether KLIPS's normal tunnel-exit check (that a packet emerging
from a tunnel has plausible addresses in its header) should be
disabled; acceptable values are yes and no (the default).
Tunnel-exit checks improve security and do not break any normal
configuration. Relevant only locally, other end need not agree on
it.
failureshunt
what to do with packets when negotiation fails. The default is
none: no shunt; passthrough, drop, and reject have the obvious
meanings.
CONN PARAMETERS: MANUAL KEYING
This command was obsoleted around the same time that Al Gore invented
the internet. ipsec manual was used in the jurassic period to load
static keys into the kernel. There are no rational reasons to use this,
and it is not supported anymore. If you need to create static SAs, then
you can use ipsec spi and ipsec eroute when using KLIPS or ip xfrm or
setkey when using NETKEY.
No rational person uses static keys. They are not easier to use.
REPEAT: they are not easier to use.
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 (see ipsec_setup(8)). Here's an example:
config setup
interfaces="ipsec0=eth1 ipsec1=ppp0"
klipsdebug=none
plutodebug=control
protostack=auto
manualstart=
Parameters are optional unless marked “(required)”.
The currently-accepted parameter names in a config setup section are:
myid
the identity to be used for %myid. %myid is used in the implicit
policy group conns and can be used as an identity in explicit
conns. If unspecified, %myid is set to the IP address in
%defaultroute (if that is supported by a TXT record in its reverse
domain), or otherwise the system's hostname (if that is supported
by a TXT record in its forward domain), or otherwise it is
undefined. An explicit value generally starts with ``@''.
protostack
decide which protocol stack is going to be used. Valid values are
"auto", "klips", "netkey" and "mast". The "mast" stack is a
variation for the klips stack.
interfaces
virtual and physical interfaces for IPsec to use: a single
virtual=physical pair, a (quoted!) list of pairs separated by white
space, or %none. One of the pairs may be written as %defaultroute,
which means: find the interface d that the default route points to,
and then act as if the value was ``ipsec0=d''. %defaultroute is
the default; %none must be used to denote no interfaces, or when
using the NETKEY stack. If %defaultroute is used (implicitly or
explicitly) information about the default route and its interface
is noted for use by ipsec_manual(8) and ipsec_auto(8).)
listen
IP address to listen on (default depends on interfaces= setting).
Currently only accepts one IP address.
nat_traversal
whether to accept/offer to support NAT (NAPT, also known as "IP
Masqurade") workaround for IPsec. Acceptable values are: yes and no
(the default). This parameter may eventually become per-connection.
disable_port_floating
whether to enable the newer NAT-T standards for port floating.
Acceptable values are no (the default) and yes .
force_keepalive
whether to force sending NAT-T keep-alives to support NAT which are
send to prevent the NAT router from closing its port when there is
not enough traffic on the IPsec connection. Acceptable values are:
yes and no (the default). This parameter may eventually become
per-connection.
keep_alive
The delay (in seconds) for NAT-T keep-alive packets, if these are
enabled using force_keepalive This parameter may eventually become
per-connection.
virtual_private
contains the networks that are allowed as subnet= for the remote
clients when using the vhost: or vnet: keywords in the subnet=
parameters. In other words, the address ranges that may live behind
a NAT router through which a client connects. This value is usually
set to all the RFC-1918 address space, excluding the space used in
the local subnet behind the NAT (An IP address cannot live at two
places at once). IPv4 address ranges are denoted as %v4:a.b.c.d/mm
and IPv6 is denoted as %v6:aaaa::bbbb:cccc:dddd:eeee/mm. One can
exclude subnets by using the !. For example, if the VPN server is
giving access to 192.168.1.0/24, this option should be set to:
virtual_private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%v4:172.16.0.0/12,%v4:!192.168.1.0/24.
This parameter is only needed on the server side and not on the
client side that resides behind the NAT router, as the client will
just use its IP address for the inner IP setting. This parameter
may eventually become per-connection. See also leftsubnet=
Note: It seems that T-Mobile in the US and Rogers/Fido in Canada
have started using 25.0.0.0/8 as their pre-NAT range. This range
technically belows to the Defence Interoperable Network Services
Authority (DINSA), an agency of the Ministry of Defence of the
United Kingdom. The network range seems to not have been announced
for decades, which is probably why these organisasions "borrowed"
this range. To support roadwarriors on these 3G networks, you might
have to add it to the virtual_private= line.
oe
a boolean (yes/no) that determines if Opportunistic Encryption will
be enabled. Opportunistic Encryption is the term to describe using
IPsec tunnels without prearrangement. It uses IPSECKEY or TXT
records to announce public RSA keys for certain IP's or identities.
For a complete description see
/doc/draft-richardson-ipsec-opportunistic.txt,
doc/opportunism-spec.txt and doc/opportunism.howto. See also the
IETF BTNS working group and RFC4025.
The default is no.
This feature is only available with kernel drivers that support the
caching of packets (%hold eroutes or equivalent) that allows us to
respond to a packet from an unknown IP address. At present only the
(klips)mast protocol stack supports this feature.
nhelpers
how many pluto helpers are started to help with cryptographic
operations. Pluto will start (n-1) of them, where n is the number
of CPU's you have (including hypherthreaded CPU's). A value of 0
forces pluto to do all operations in the main process. A value of
-1 tells pluto to perform the above calculation. Any other value
forces the number to that amount.
crlcheckinterval
interval, specified in seconds, after which pluto will verify
loaded X.509 CRL's for expiration. If any of the CRL's is expired,
or if they previously failed to get updated, a new attempt at
updating the CRL is made. The first attempt to update a CRL is
started at two times the crlcheckinterval. If set to 0, which is
also the default value if this option is not specified, CRL
updating is disabled.
strictcrlpolicy
if not set, pluto is tolerant about missing or expired X.509
Certificate Revocation Lists (CRL's), and will allow peer
certificates as long as they do not appear on an expired CRL. When
this option is enabled, all connections with an expired or missing
CRL will be denied. Active connections will be terminated at rekey
time. This setup is more secure, but also dangerous. If the CRL is
fetched through an IPsec tunnel with a CRL that expired, the entire
VPN server will be dead in the water until a new CRL is manually
transferred to the machine (if it allows non-IPsec connections).
Acceptable values are yes or no (the default).
forwardcontrol
This option is obsolete and ignored. Please use
net.ipv4.ip_forward = 0 in /etc/sysctl.conf instead to control the
ip forwarding behaviour.
rp_filter
This option is obsolete and ignored. Please use the
net.ipv4.conf/[iface]/rp_filter = 0 options in /etc/sysctl.conf
instead. This option is badly documented; it must be 0 in many
cases for ipsec to function.
syslog
the syslog(2) “facility” name and priority to use for
startup/shutdown log messages, default daemon.error.
klipsdebug
how much KLIPS 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 separated by white space) are
enabled; for details on available debugging types, see
ipsec_klipsdebug(8). This KLIPS option has no effect on NETKEY,
Windows or BSD stacks.
plutodebug
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 ipsec_pluto(8).
uniqueids
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.
plutorestartoncrash
prevent pluto from restarting after it crashed. This option should
only be used when debugging a crasher. It will prevent overwriting
a core file on a new start, or a cascade of core files. This option
is also required if used with plutostderrlog= to avoid clearing the
logs of the crasher. Values can be yes (the default) or no.
plutoopts
additional options to pass to pluto upon startup. See
ipsec_pluto(8).
plutostderrlog
do not use syslog, but rather log to stderr, and direct stderr to
the argument file.
pluto
whether to start Pluto or not; Values are yes (the default) or no
(useful only in special circumstances).
plutowait
should Pluto wait for each negotiation attempt that is part of
startup to finish before proceeding with the next? Values are yes
or no (the default).
prepluto
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.
postpluto
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.
dumpdir
in what directory should things started by setup (notably the Pluto
daemon) be allowed to dump core? The empty value (the default)
means they are not allowed to.
fragicmp
whether a tunnel's need to fragment a packet should be reported
back with an ICMP message, in an attempt to make the sender lower
his PMTU estimate; acceptable values are yes (the default) and no.
This KLIPS option has no effect on NETKEY, Windows or BSD stacks.
hidetos
whether a tunnel packet's TOS field should be set to 0 rather than
copied from the user packet inside; acceptable values are yes (the
default) and no. This KLIPS option has no effect on NETKEY, Windows
or BSD stacks.
overridemtu
value that the MTU of the ipsecn interface(s) should be set to,
overriding IPsec's (large) default. This parameter is needed only
in special situations. This KLIPS option has no effect on NETKEY,
Windows or BSD stacks.
IMPLICIT CONNS
The system automatically defines several conns to implement default
policy groups. Each can be overridden by explicitly defining a new conn
with the same name. If the new conn has auto=ignore, the definition is
suppressed.
Here are the automatically supplied definitions.
conn clear
type=passthrough
authby=never
left=%defaultroute
right=%group
auto=route
conn clear-or-private
type=passthrough
left=%defaultroute
leftid=%myid
right=%opportunisticgroup
failureshunt=passthrough
keyingtries=3
ikelifetime=1h
salifetime=1h
rekey=no
auto=route
conn private-or-clear
type=tunnel
left=%defaultroute
leftid=%myid
right=%opportunisticgroup
failureshunt=passthrough
keyingtries=3
ikelifetime=1h
salifetime=1h
rekey=no
auto=route
conn private
type=tunnel
left=%defaultroute
leftid=%myid
right=%opportunisticgroup
failureshunt=drop
keyingtries=3
ikelifetime=1h
salifetime=1h
rekey=no
auto=route
conn block
type=reject
authby=never
left=%defaultroute
right=%group
auto=route
# default policy
conn packetdefault
type=tunnel
left=%defaultroute
leftid=%myid
left=0.0.0.0/0
right=%opportunistic
failureshunt=passthrough
keyingtries=3
ikelifetime=1h
salifetime=1h
rekey=no
auto=route
These conns are not affected by anything in conn %default. They will
only work if %defaultroute works. The leftid will be the interfaces IP
address; this requires that reverse DNS records be set up properly.
The implicit conns are defined after all others. It is appropriate and
reasonable to use also=private-or-clear (for example) in any other
opportunistic conn.
POLICY GROUP FILES
The optional files under /etc/ipsec.d/policy, including
/etc/ipsec.d/policies/clear
/etc/ipsec.d/policies/clear-or-private
/etc/ipsec.d/policies/private-or-clear
/etc/ipsec.d/policies/private
/etc/ipsec.d/policies/block
may contain policy group configuration information to supplement
ipsec.conf. Their contents are not security-sensitive.
These files are text files. Each consists of a list of CIDR blocks, one
per line. White space followed by # followed by anything to the end of
the line is a comment and is ignored, as are empty lines.
A connection in ipsec.conf which has right=%group or
right=%opportunisticgroup is a policy group connection. When a policy
group file of the same name is loaded, with
ipsec auto --rereadgroups
or at system start, the connection is instantiated such that each CIDR
block serves as an instance's right value. The system treats the
resulting instances as normal connections.
For example, given a suitable connection definition private, and the
file /etc/ipsec.d/policy/private with an entry 192.0.2.3, the system
creates a connection instance private#192.0.2.3. This connection
inherits all details from private, except that its right client is
192.0.2.3.
DEFAULT POLICY GROUPS
The standard Openswan install includes several policy groups which
provide a way of classifying possible peers into IPsec security
classes: private (talk encrypted only), private-or-clear (prefer
encryption), clear-or-private (respond to requests for encryption),
clear and block. Implicit policy groups apply to the local host only,
and are implemented by the IMPLICIT CONNECTIONS described above.
CHOOSING A CONNECTION [THIS SECTION IS EXTREMELY OUT OF DATE
When choosing a connection to apply to an outbound packet caught with a
%trap, the system prefers the one with the most specific eroute that
includes the packet's source and destination IP addresses. Source
subnets are examined before destination subnets. For initiating, only
routed connections are considered. For responding, unrouted but added
connections are considered.
When choosing a connection to use to respond to a negotiation which
doesn't match an ordinary conn, an opportunistic connection may be
instantiated. Eventually, its instance will be /32 -> /32, but for
earlier stages of the negotiation, there will not be enough information
about the client subnets to complete the instantiation.
FILES
/etc/ipsec.conf
/etc/ipsec.d/policies/clear
/etc/ipsec.d/policies/clear-or-private
/etc/ipsec.d/policies/private-or-clear
/etc/ipsec.d/policies/private
/etc/ipsec.d/policies/block
SEE ALSOipsec(8), ipsec_ttoaddr(8), ipsec_auto(8), ipsec_manual(8),
ipsec_rsasigkey(8)HISTORY
Designed for the FreeS/WAN project <http://www.freeswan.org> by Henry
Spencer.
BUGS
Before reporting new bugs, please ensure you are using the latest
version of Openswan, and if not using KLIPS, please ensure you are
using the latest kernel code for your IPsec stack.
When type or failureshunt is set to drop or reject, Openswan blocks
outbound packets using eroutes, but assumes inbound blocking is handled
by the firewall. Openswan offers firewall hooks via an “updown” script.
However, the default ipsec _updown provides no help in controlling a
modern firewall.
Including attributes of the keying channel (authentication methods,
ikelifetime, etc.) as an attribute of a connection, rather than of a
participant pair, is dubious and incurs limitations.
The use of %any with the protoport= option is ambiguous. Should the SA
permits any port through or should the SA negotiate any single port
through? The first is a basic conn with a wildcard. The second is a
template. The second is the current behaviour, and it's wrong for quite
a number of uses involving TCP. The keyword %one may be introduced in
the future to separate these two cases.
ipsec_manual is not nearly as generous about the syntax of subnets,
addresses, etc. as the usual Openswan user interfaces. Four-component
dotted-decimal must be used for all addresses. It is smart enough to
translate bit-count netmasks to dotted-decimal form.
It would be good to have a line-continuation syntax, especially for the
very long lines involved in RSA signature keys.
First packet caching is only implemented for the KLIPS(NG) and MAST
stacks. NETKEY returns POSIX-breaking responses, visiable as connect:
Resource temporarily unavailable errors. This affects Opportunistic
Encryption and DPD. Functionality on the BSD and Windows stacks is
unknown.
Some state information is only available when using KLIPS, and will
return errors on other IPsec stacks. These include ipsec eroute, ipsec
spi and ipsec look.
Multiple L2TP clients behind the same NAT router, and multiple L2TP
clients behind different NAT routers using the same Virtual IP is
currently only working for the KLIPSNG stack.
The ability to specify different identities, authby, and public keys
for different automatic-keyed connections between the same participants
is misleading; this doesn't work dependably because the identity of the
participants is not known early enough. This is especially awkward for
the “Road Warrior” case, where the remote IP address is specified as
0.0.0.0, and that is considered to be the “participant” for such
connections.
In principle it might be necessary to control MTU on an
interface-by-interface basis, rather than with the single global
override that overridemtu provides. This feature is planned for a
future release.
A number of features which could be implemented in both manual and
automatic keying actually are not yet implemented for manual keying.
This is unlikely to be fixed any time soon.
If conns are to be added before DNS is available, left=FQDN,
leftnextop=FQDN, and leftrsasigkey=%dnsonload will fail.
ipsec_pluto(8) does not actually use the public key for our side of a
conn but it isn't generally known at a add-time which side is ours
(Road Warrior and Opportunistic conns are currently exceptions).
The myid option does not affect explicit
ipsec auto --add or ipsec auto --replace commands for implicit conns.
[FIXME: source] 03/23/2012 IPSEC.CONF(5)
