.\"	$OpenBSD: ipsec.conf.5,v 1.27 2005/11/24 13:53:41 hshoexer Exp $
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.\" Copyright (c) 2004 Mathieu Sauve-Frankel  All rights reserved.
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.Dd April 9, 2005
.Dt IPSEC.CONF 5
.Os
.Sh NAME
.Nm ipsec.conf
.Nd IPsec configuration file
.Sh DESCRIPTION
The
.Nm
file specifies rules and definitions for
.Xr ipsec 4
IP security services.
The rulesets themselves can be loaded, viewed, and modified via the
.Xr ipsecctl 8
userland utility.
.Sh FLOWS
IPsec uses
.Em flows
to determine whether to apply security services to an IP packet or not.
The following security services are available:
.Bl -tag -width xxxx
.It Ic flow esp
ESP can provide the following properties:
authentication, integrity, replay protection, and confidentiality of the data.
.It Ic flow ah
AH provides authentication, integrity, and replay protection, but no
confidentiality.
.El
.Pp
For details on ESP and AH see
.Xr ipsec 4 .
When no service is specified,
.Xr ipsecctl 8
will use ESP.
The settings for the security services have to be negotiated by
.Xr isakmpd 8 .
As soon as a packet matches a flow,
.Xr isakmpd 8
automatically starts the negotiation.
See
.Xr isakmpd 8
for details.
.Pp
Parameters specify the packets to which a flow applies.
Some parameters are optional.
.Bl -tag -width xxxx
.It Ar in No or Ar out
This rule applies to incoming or outgoing packets.
If neither
.Ar in
nor
.Ar out
are specified,
.Xr ipsecctl 8
will assume the direction
.Ar out
for this rule and will construct a proper
.Ar in
rule.
Thus packets in both directions will be matched.
.It Xo
.Ar from
.Aq Ar src
.Ar to
.Aq Ar dst
.Ar peer
.Aq Ar remote
.Xc
This rule applies for packets with source address
.Aq Ar src
and destination address
.Aq Ar dst .
All addresses are specified in CIDR notation.
The keyword
.Ar any
will match any address (i.e. 0.0.0.0/0).
The
.Ar peer
parameter specifies the address of the remote endpoint of this particular
flow.
For host-to-host connections where
.Aq Ar dst
is identical to
.Aq Ar remote ,
the
.Ar peer
specification can be left out.
.El
.Sh IPSEC SAs
The security parameters for a
.Ar flow
are stored in the Security Association Database
(SADB).
The following rules enter SAs in the SADB:
.Pp
.Bl -tag -width Ds -offset indent -compact
.It Ic esp
Enter an ESP SA.
.It Ic ah
Enter an AH SA.
.It Ic ipcomp
Enter an IPCOMP SA.
.El
.Pp
Parameters specify the peers, Security Parameter Index (SPI),
cryptographic transforms, and key material to be used.
.Bl -tag -width xxxx
.It Xo
.Ar from
.Aq Ar src
.Ar to
.Aq Ar dst
.Xc
This SA is for a
.Ar flow
between the peers
.Aq Ar src
and
.Aq Ar dst .
.It Xo
.Ar spi
.Aq Ar number
.Xc
The SPI identifies a specific SA.
.Ar number
is a 32-bit value and needs to be unique.
.It Xo
.Ar auth
.Aq Ar algorithm
.Xc
For both
.Ar esp
and
.Ar ah
an authentication algorithm can be specified.
Possible algorithms are
.Ar hmac-md5 ,
.Ar hmac-ripemd160 ,
.Ar hmac-sha1 ,
.Ar hmac-sha2-256 ,
.Ar hmac-sha2-384 ,
and
.Ar hmac-sha2-512 .
.Pp
If no algorithm is specified,
.Xr ipsecctl 8
will choose
.Ar hmac-sha2-256
by default.
.It Xo
.Ar comp
.Aq Ar algorithm
.Xc
The compression algorithm to be used.
Possible algorithms are
.Ar deflate
and
.Ar lzs .
Note that
.Ar lzs
is only available with
.Xr hifn 4
because of the patent held by Hifn, Inc.
.It Xo
.Ar enc
.Aq Ar algorithm
.Xc
For
.Ar esp
an encryption algorithm needs to be specified.
Possible algorithms are
.Ar 3des-cbc ,
.Ar des-cbc ,
.Ar aes ,
.Ar aesctr ,
.Ar blowfish ,
.Ar cast128 ,
.Ar null ,
and
.Ar skipjack .
.Pp
If no algorithm is specified,
.Xr ipsecctl 8
will choose
.Ar aesctr
by default.
.It Xo
.Ar authkey
.Aq Ar keyspec
.Xc
.Ar keyspec
defines the authentication key to be used.
It is either a hexadecimal string or a path to a file containing the key.
The filename may be given as either an absolute path to the file
or a relative pathname,
and is specified as follows:
.Bd -literal -offset -indent
authkey file "filename"
.Ed
.It Xo
.Ar enckey
.Aq Ar keyspec
.Xc
The encryption key is defined similar to
.Ar authkey .
.El
.Pp
It is very important that keys are not guessable.
One practical way of generating 160-bit (20-byte) keys is a follows:
.Bd -literal -offset indent
$ openssl rand 20 | hexdump -e '20/1 "%02x"'
.Ed
.Pp
For
.Ar spi ,
.Ar authkey ,
and
.Ar enckey ,
it is possible to specify two colon separated values.
.Xr ipsecctl 8
will then generate the matching incoming SA using the second values for
.Ar spi ,
.Ar authkey ,
and
.Ar enckey .
.Sh AUTOMATIC KEYING USING ISAKMP/IKE
Rules can also specify IPsec flows and SAs to be established automatically by
.Xr isakmpd 8 .
This is accomplished by the following rule:
.Bl -tag -width xxxx
.It Ic ike esp
Creates an IPsec tunnel using ESP.
.El
.Pp
Note that AH and transport mode are not yet supported.
See
.Xr isakmpd 8
for details on ISAKMP/IKE.
.Pp
Parameters specify the packets that will go through the tunnel and which
cryptographic transforms are used for
.Xr isakmpd 8 .
Some parameters are optional.
.Bl -tag -width xxxx
.It Xo
.Ar passive
.Xc
When
.Ar passive
is specified
.Xr isakmpd 8
will not immediately start negotiation of this tunnel, but wait for an incoming
request from the remote peer.
If not specified,
.Xr isakmpd 8
will start negotiation at once.
.It Xo
.Ar from
.Aq Ar src
.Ar to
.Aq Ar dst
.Ar peer
.Aq Ar remote
.Xc
This rule applies for packets with source address
.Aq Ar src
and destination address
.Aq Ar dst .
All addresses are specified in CIDR notation.
The keyword
.Ar any
will match any address (i.e. 0.0.0.0/0).
The
.Ar peer
parameter specifies the address of the remote endpoint of this particular
flow.
For host-to-host connections where
.Aq Ar dst
is identical to
.Aq Ar remote ,
the
.Ar peer
specification can be left out.
.It Xo
.Ar main auth
.Aq Ar algorithm
.Ar enc
.Aq Ar algorithm
.Xc
These paramters define the cryptographic transforms to be used for main mode.
Possible values for
.Aq Ar auth
are
.Ar hmac-sha1
and
.Ar hmac-md5 .
For
.Aq Ar enc
the values
.Ar des ,
.Ar 3des ,
.Ar aes ,
.Ar blowfish
and
.Ar cast
are allowed.
If omitted,
.Xr isakmpd 8
will use the default values
.Ar hmac-sha1
and
.Ar 3des .
.It Xo
.Ar quick auth
.Aq Ar algorithm
.Ar enc
.Aq Ar algorithm
.Xc
Similar to
.Ar main ,
.Ar quick
defines the transforms to be used for quick mode.
However, the possible values for
.Aq Ar auth
are
.Ar hmac-md5 ,
.Ar hmac-sha1 ,
.Ar hmac-ripemd160 ,
.Ar hmac-sha2-256 ,
.Ar hmac-sha2-384
and
.Ar hmac-sha2-512 .
For
.Ar enc
valid values are again
.Ar des ,
.Ar 3des ,
.Ar aes ,
.Ar blowfish
and
.Ar cast .
If no quick mode transforms are specified,
the default values
.Ar hmac-sha2-256
and
.Ar aes
are chosen.
.It Xo
.Ar srcid
.Aq Ar fqdn
.Xc
This optional parameter defines a FQDN that will be used by
.Xr isakmpd 8
as the identity of the local peer.
.It Xo
.Ar dstid
.Aq Ar fqdn
.Xc
Similar to
.Ar srcid ,
this optional parameter defines a FQDN to be used by the remote peer.
.El
.Pp
Note that
.Xr isakmpd 8
will use RSA authentication.
By default, the system startup script
.Xr rc 8
generates a key-pair when starting, if one does not already exist.
.Pp
See also
.Sx ISAKMP EXAMPLES
below.
.Sh TCP MD5 SIGNATURES
RFC 2385 describes a mechanism to protect
.Xr tcp 4
sessions using MD5.
A Security Association (SA) for TCP MD5 signatures is set up using the
following rule:
.Bl -tag -width xxxx
.It Xo
.Ar tcpmd5
.Ar from
.Aq Ar src
.Ar to
.Aq Ar dst
.Ar spi
.Aq Ar number
.Ar authkey
.Aq Ar keyspec
.Xc
This rule applies for packets with source address
.Aq Ar src
and destination address
.Aq Ar dst .
All addresses are specified in CIDR notation.
The parameter
.Ar spi
is a 32-bit value defining the Security Parameter Index (SPI) for this SA.
.Pp
The authentication key to be used is a hexadecimal string of arbitrary length
or a path to a file containing the key.
The filename may be given as either an absolute path to the file
or a relative pathname,
and is specified as follows:
.Bd -literal -offset -indent
authkey file "filename"
.Ed
.Pp
It is very important that the key is not guessable.
One practical way of generating 160-bit (20-byte) keys is as follows:
.Bd -literal -offset indent
$ openssl rand 20 | hexdump -e '20/1 "%02x"'
.Ed
.Pp
For both
.Ar spi
and
.Ar authkey
it is possible to specify two values separated by a colon.
.Xr ipsecctl 8
will then generate the matching incoming SA using the second values for
.Ar spi
and
.Ar authkey .
.El
.Pp
For details on how to enable TCP MD5 signatures see
.Xr tcp 4 .
.Sh EXAMPLES
.Bd -literal
# Host-to-host
flow esp from 192.168.3.14 to 192.168.3.100

# Same as above, but explicitly specifying "in" and "out" rules
flow esp out from 192.168.3.14  to 192.168.3.100
flow esp in  from 192.168.3.100 to 192.168.3.14

# Net-to-net
flow esp from 192.168.7.0/24 to 192.168.8.0/24 peer 192.168.3.12

# Same as above, but explicitly specifying "in" and "out" rules
flow esp out from 192.168.7.0/24 to 192.168.8.0/24 peer 192.168.3.12
flow esp in  from 192.168.8.0/24 to 192.168.7.0/24 peer 192.168.3.12

# Set up IPsec SAs for flows between 192.168.3.14 and 192.168.3.12
esp from 192.168.3.14 to 192.168.3.12 spi 0xdeadbeef:0xbeefdead \e
	auth hmac-sha2-256 enc aesctr authkey file "auth14:auth12" \e
	enckey file "enc14:enc12"
.Ed
.Sh TCP MD5 EXAMPLES
.Bd -literal
# Set up keys for TCP MD5 signatures
tcpmd5 from 192.168.3.14 to 192.168.3.27 spi 0x1000:0x1001 \e
	authkey 0xdeadbeef:0xbeefdead

# Set up keys for TCP MD5 signatures; read keys from files
tcpmd5 from 192.168.3.14 to 192.168.3.27 spi 0x1000:0x1001 \e
	authkey file "/path/to/key1:/path/to/key2"
.Ed
.Sh ISAKMP EXAMPLES
.Bd -literal
# Set up two tunnels:
# First between the networks 10.1.1.0/24 and 10.1.2.0/24
# Second between the machines 192.168.3.1 and 192.168.3.2

ike esp from 10.1.1.0/24 to 10.1.2.0/24 peer 192.168.3.2
ike esp from 192.168.3.1 to 192.168.3.2
.Ed
.Sh SEE ALSO
.Xr ipcomp 4 ,
.Xr ipsec 4 ,
.Xr tcp 4 ,
.Xr isakmpd.conf 5 ,
.Xr ipsecctl 8 ,
.Xr isakmpd 8 ,
.Xr vpn 8
.Sh HISTORY
The
.Nm
file format first appeared in
.Ox 3.8 .