134 lines
4.1 KiB
Groff
134 lines
4.1 KiB
Groff
.\" $OpenBSD: enc.4,v 1.22 2006/05/26 08:51:29 jmc Exp $
|
|
.\"
|
|
.\" Copyright (c) 1999 Angelos D. Keromytis
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\"
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by Angelos D. Keromytis.
|
|
.\" 4. The name of the author may not be used to endorse or promote products
|
|
.\" derived from this software without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd November 28, 2007
|
|
.Dt ENC 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm enc
|
|
.Nd Encapsulating Interface
|
|
.Sh SYNOPSIS
|
|
To compile this driver into the kernel,
|
|
place the following line in your
|
|
kernel configuration file:
|
|
.Bd -ragged -offset indent
|
|
.Cd "device enc"
|
|
.Ed
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
interface is a software loopback mechanism that allows hosts or
|
|
firewalls to filter
|
|
.Xr ipsec 4
|
|
traffic using any firewall package that hooks in via the
|
|
.Xr pfil 9
|
|
framework.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
interface allows an administrator to see incoming and outgoing packets
|
|
before and after they will be or have been processed by
|
|
.Xr ipsec 4
|
|
via
|
|
.Xr tcpdump 1 .
|
|
.Pp
|
|
The
|
|
.Dq Li enc0
|
|
interface inherits all IPsec traffic.
|
|
Thus all IPsec traffic can be filtered based on
|
|
.Dq Li enc0 ,
|
|
and all IPsec traffic could be seen by invoking
|
|
.Xr tcpdump 1
|
|
on the
|
|
.Dq Li enc0
|
|
interface.
|
|
.Pp
|
|
What can be seen with
|
|
.Xr tcpdump 1
|
|
and what will be passed on to the firewalls via the
|
|
.Xr pfil 9
|
|
framework can be independently controlled using the following
|
|
.Xr sysctl 8
|
|
variables:
|
|
.Bl -column net.enc.out.ipsec_filter_mask 0x00000000 0x00000000
|
|
.It Sy "Name Defaults Suggested"
|
|
.It "net.enc.out.ipsec_bpf_mask 0x00000003 0x00000001"
|
|
.It "net.enc.out.ipsec_filter_mask 0x00000001 0x00000001"
|
|
.It "net.enc.in.ipsec_bpf_mask 0x00000001 0x00000002"
|
|
.It "net.enc.in.ipsec_filter_mask 0x00000001 0x00000002"
|
|
.El
|
|
.Pp
|
|
For the incoming path a value of
|
|
.Li 0x1
|
|
means
|
|
.Dq Li before stripping off the outer header
|
|
and
|
|
.Li 0x2
|
|
means
|
|
.Dq Li after stripping off the outer header .
|
|
For the outgoing path
|
|
.Li 0x1
|
|
means
|
|
.Dq Li with only the inner header
|
|
and
|
|
.Li 0x2
|
|
means
|
|
.Dq Li with outer and inner headers .
|
|
.Bd -literal
|
|
incoming path |------|
|
|
---- IPsec processing ---- (before) ---- (after) ----> | |
|
|
| Host |
|
|
<--- IPsec processing ---- (after) ----- (before) ---- | |
|
|
outgoing path |------|
|
|
.Ed
|
|
.Pp
|
|
Most people will want to run with the suggested defaults for
|
|
.Cm ipsec_filter_mask
|
|
and rely on the security policy database for the outer headers.
|
|
.Sh EXAMPLES
|
|
To see the packets the processed via
|
|
.Xr ipsec 4 ,
|
|
adjust the
|
|
.Xr sysctl 8
|
|
variables according to your need and run:
|
|
.Pp
|
|
.Dl "tcpdump -i enc0"
|
|
.Sh SEE ALSO
|
|
.Xr tcpdump 1 ,
|
|
.Xr bpf 4 ,
|
|
.Xr ipf 4 ,
|
|
.Xr ipfw 4 ,
|
|
.Xr ipsec 4 ,
|
|
.Xr pf 4 ,
|
|
.Xr tcpdump 8
|