.\" Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. .\" 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. Neither the name of the project nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``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 PROJECT OR CONTRIBUTORS 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. .\" .\" $NetBSD: ipsec.4,v 1.3 1999/07/17 06:57:59 itojun Exp $ .\" KAME Id: ipsec.4,v 1.1.2.3 1999/04/28 06:39:52 sakane Exp .\" .Dd January 29, 1999 .Dt IPSEC 4 .Os .Sh NAME .Nm ipsec .Nd IP security protocol .Sh SYNOPSIS .Fd #include .Fd #include .Fd #include .Sh DESCRIPTION .Nm is a security protocol in Internet Protocol layer. .Nm is defined for both IPv4 .Pq Xr inet 4 and IPv6 .Pq Xr inet6 4 . .Nm consists of two sub-protocols, namely ESP .Pq encapsulated security payload and AH .Pq authentication header . ESP protects IP payload from wire-tapping by encrypting it by secret key cryptography algorithms. AH guarantees integrity of IP packet and protects it from intermediate alteration or impersonation, by attaching cryptographic checksum computed by one-way hash functions. .Nm has two operation modes: transport mode and tunnel mode. Transport mode is for protecting peer-to-peer commuication between end nodes. Tunnel mode includes IP-in-IP encapsulation operation and is designed for security gateways, like VPN configurations. .\" .Sh KERNEL INTERFACE .Nm is controlled by key management engine, and policy engine in the operating system kernel. .Pp Key management engine can be accessed from the userland by using .Dv PF_KEY sockets. The .Dv PF_KEY socket API is defined in RFC2367. .Pp Policy engine can be controlled by .Dv PF_KEY API, .Xr setsockopt 2 operations, and .Xr sysctl 3 interface. .Dv PF_KEY interface is an extension to RFC2367, and defines IPsec policy like per-packet filters. .Xr setsockopt 2 interface is used to define per-socket behavior, and .Xr sysctl 3 interface is used to define host-wide default behavior. .Pp The kernel code does not implement dynamic encryption key exchange protocol like IKE .Pq Internet Key Exchange . That should be implemented as userland programs, or daemons, by using the above described APIs. .\" .Sh POLICY MANAGEMENT The policy management code is experimental, but this is almostly conformed to RFC2401. You can manage the SPD by two way. One is the way to use .Xr setkey 8 , and other is the way to use .Xr setsockopt 3 . .Xr setkey 8 can define either .Nm default , use or .Nm require like filtering rule. and .Xr setsockopt 3 can define either .Nm entrust , ipsec or .Nm bypass as Security level per socket. .Pp When .Nm default (or .Nm entrust ) is defined, Policy engine consults to system wide default defined .Xr sysctl 8 .Bl -column net.inet6.ipsec6.esp_trans_deflev integerxxx .It Sy Name Type Changeable .It net.inet.ipsec.esp_trans_deflev integer yes .It net.inet.ipsec.esp_net_deflev integer yes .It net.inet.ipsec.ah_trans_deflev integer yes .It net.inet.ipsec.ah_net_deflev integer yes .It net.inet6.ipsec6.esp_trans_deflev integer yes .It net.inet6.ipsec6.esp_net_deflev integer yes .It net.inet6.ipsec6.ah_trans_deflev integer yes .It net.inet6.ipsec6.ah_net_deflev integer yes .El .Pp They are 1:use or 2:require. .Pp If kernel doesn't find out policy entry, then system wide default is applied. You can specify the system wide default as discarding packet or not to do IPsec. .Bl -column net.inet6.ipsec6.def_policy integerxxx .It Sy Name Type Changeable .It net.inet.ipsec.def_policy integer yes .It net.inet6.ipsec6.def_policy integer yes .El .Pp They are 0:discard or 1:none. .\" .Sh PROTOCOLS The .Nm protocol works like plug-in to .Xr inet 4 and .Xr inet6 4 protocols. Therefore, .Nm supports most of the protocols defined upon those IP-layer protocols. Some of the protocols, like .Xr icmp 4 or .Xr icmp6 4 , may behave differently with .Nm ipsec . This is because .Nm can prevent .Xr icmp 4 or .Xr icmp6 4 routines from looking into IP payload. .\" .Sh SEE ALSO .Xr ioctl 2 , .Xr socket 2 , .Xr sysctl 3 , .Xr icmp6 4 , .Xr intro 4 , .Xr ip6 4 , .Xr setkey 8 , .Xr racoon 8 .Pp .%T RFC2367 .Rs .%A "D. L. McDonald" .%T "A Simple IP Security API Extension to BSD Sockets" .%N "draft-mcdonald-simple-ipsec-api-03.txt" .%O "internet draft" .Re .Sh CAVEAT The IPsec support is subject to change as the Internet protocols develop. .Pp There is no single standard for policy engine API, so the policy engine API described herein is just for KAME implementation. .\" .Sh HISTORY The implementation described herein appeared in WIDE/KAME IPv6/IPsec stack.