229 lines
6.3 KiB
Groff
229 lines
6.3 KiB
Groff
.\" Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the project nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $Id: ipsec.4,v 1.2 1999/10/07 03:55:08 itojun Exp $
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.\" $FreeBSD$
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.\"
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.Dd January 29, 1999
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.Dt IPSEC 4
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.Os KAME
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.Sh NAME
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.Nm ipsec
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.Nd IP security protocol
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <netinet/in.h>
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.Fd #include <netinet6/ipsec.h>
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.Sh DESCRIPTION
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.Nm
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is a security protocol in Internet Protocol layer.
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.Nm
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is defined for both IPv4 and IPv6
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.Po
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.Xr inet 4
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and
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.Xr inet6 4
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.Pc .
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.Nm
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consists of two sub-protocols, namely
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ESP
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.Pq encapsulated security payload
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and AH
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.Pq authentication header .
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ESP protects IP payload from wire-tapping by encrypting it by
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secret key cryptography algorithms.
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AH guarantees integrity of IP packet
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and protects it from intermediate alteration or impersonation,
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by attaching cryptographic checksum computed by one-way hash functions.
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.Nm
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has two operation modes: transport mode and tunnel mode.
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Transport mode is for protecting peer-to-peer commuication between end nodes.
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Tunnel mode includes IP-in-IP encapsulation operation
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and is designed for security gateways, like VPN configurations.
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.\"
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.Sh KERNEL INTERFACE
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.Nm
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is controlled by key management engine, and policy engine in the
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operating system kernel.
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.Pp
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Key management engine can be accessed from the userland by using
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.Dv PF_KEY
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sockets.
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The
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.Dv PF_KEY
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socket API is defined in RFC2367.
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.Pp
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Policy engine can be controlled by extended part of
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.Dv PF_KEY
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API,
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.Xr setsockopt 2
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operations, and
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.Xr sysctl 3
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interface.
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The kernel implements
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extended version of
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.Dv PF_KEY
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interface, and allows you to define IPsec policy like per-packet filters.
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.Xr setsockopt 2
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interface is used to define per-socket behavior, and
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.Xr sysctl 3
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interface is used to define host-wide default behavior.
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.Pp
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The kernel code does not implement dynamic encryption key exchange protocol
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like IKE
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.Pq Internet Key Exchange .
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That should be implemented as userland programs
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.Pq usually as daemons ,
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by using the above described APIs.
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.\"
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.Sh POLICY MANAGEMENT
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The kernel implements experimental policy management code.
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You can manage the IPsec policy in two ways.
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One is to configure per-socket policy using
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.Xr setsockopt 3 .
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The other is to configure kernel packet filter-based policy using
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.Dv PF_KEY
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interface, via
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.Xr setkey 8 .
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In both cases, IPsec policy must be specified with syntax described in
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.Xr ipsec_set_policy 3 .
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.Pp
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With
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.Xr setsockopt 3 ,
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you can define IPsec policy in per-socket basis.
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You can enforce particular IPsec policy onto packets that go through
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particular socket.
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.Pp
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With
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.Xr setkey 8
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you can define IPsec policy against packets,
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using sort of packet filtering rule.
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Refer to
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.Xr setkey 8
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on how to use it.
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.Pp
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In the latter case,
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.Dq Li default
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policy is allowed for use with
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.Xr setkey 8 .
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By configuring policy to
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.Li default ,
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you can refer system-wide
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.Xr sysctl 8
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variable for default settings.
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The following variables are available.
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.Li 1
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means
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.Dq Li use ,
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and
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.Li 2
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means
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.Dq Li require
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in the syntax.
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.Bl -column net.inet6.ipsec6.esp_trans_deflev integerxxx
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.It Sy Name Type Changeable
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.It net.inet.ipsec.esp_trans_deflev integer yes
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.It net.inet.ipsec.esp_net_deflev integer yes
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.It net.inet.ipsec.ah_trans_deflev integer yes
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.It net.inet.ipsec.ah_net_deflev integer yes
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.It net.inet6.ipsec6.esp_trans_deflev integer yes
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.It net.inet6.ipsec6.esp_net_deflev integer yes
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.It net.inet6.ipsec6.ah_trans_deflev integer yes
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.It net.inet6.ipsec6.ah_net_deflev integer yes
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.El
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.Pp
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If kernel finds no matching policy system wide default value is applied.
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System wide default is specified by the following
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.Xr sysctl 8
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variables.
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.Li 0
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means
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.Dq Li discard
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which asks the kernel to drop the packet.
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.Li 1
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means
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.Dq Li none .
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.Bl -column net.inet6.ipsec6.def_policy integerxxx
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.It Sy Name Type Changeable
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.It net.inet.ipsec.def_policy integer yes
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.It net.inet6.ipsec6.def_policy integer yes
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.El
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.\"
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.Sh PROTOCOLS
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The
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.Nm
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protocol works like plug-in to
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.Xr inet 4
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and
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.Xr inet6 4
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protocols.
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Therefore,
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.Nm
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supports most of the protocols defined upon those IP-layer protocols.
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Some of the protocols, like
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.Xr icmp 4
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or
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.Xr icmp6 4 ,
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may behave differently with
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.Nm ipsec .
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This is because
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.Nm
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can prevent
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.Xr icmp 4
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or
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.Xr icmp6 4
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routines from looking into IP payload.
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.\"
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.Sh SEE ALSO
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.Xr ioctl 2 ,
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.Xr socket 2 ,
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.Xr ipsec_set_policy 3 ,
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.Xr icmp6 4 ,
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.Xr intro 4 ,
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.Xr ip6 4 ,
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.Xr setkey 8 ,
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.Xr sysctl 8 ,
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.Xr racoon 8 .
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.Pp
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.Rs
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.%T RFC2367
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.Re
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.Rs
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.%A "D. L. McDonald"
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.%T "A Simple IP Security API Extension to BSD Sockets"
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.%N "draft-mcdonald-simple-ipsec-api-03.txt"
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.%O "internet draft"
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.Re
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.Sh CAVEAT
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The IPsec support is subject to change as the IPsec protocols develop.
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.Pp
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There is no single standard for policy engine API,
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so the policy engine API described herein is just for KAME implementation.
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.\"
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.Sh HISTORY
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The implementation described herein appeared in WIDE/KAME IPv6/IPsec stack.
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