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$NetBSD: ipsec.4,v 1.4 2000/01/19 06:59:32 itojun Exp $
KAME Id: ipsec.4,v 1.4 2000/01/19 06:56:51 itojun Exp
.Dd January 29, 1999 .Dt IPSEC 4 .Os .Sh NAME .Nm ipsec .Nd IP security protocol .Sh SYNOPSIS .Fd #include <sys/types.h> .Fd #include <netinet/in.h> .Fd #include <netinet6/ipsec.h> .Sh DESCRIPTION .Nm is a security protocol in Internet Protocol layer. .Nm is defined for both IPv4 and IPv6
o .Xr inet 4 and .Xr inet6 4
c . .Nm consists of two sub-protocols, namely ESP
q encapsulated security payload and AH
q 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.
p 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.
p Policy engine can be controlled by extended part of .Dv PF_KEY API, .Xr setsockopt 2 operations, and .Xr sysctl 3 interface. The kernel implements extended version of .Dv PF_KEY interface, and allows you to define 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.
p The kernel code does not implement dynamic encryption key exchange protocol like IKE
q 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.
p When .Nm default (or .Nm entrust ) is defined, Policy engine consults to system wide default defined .Xr sysctl 8 l -column net.inet6.ipsec6.esp_trans_deflev integerxxx t Sy Name Type Changeable t net.inet.ipsec.esp_trans_deflev integer yes t net.inet.ipsec.esp_net_deflev integer yes t net.inet.ipsec.ah_trans_deflev integer yes t net.inet.ipsec.ah_net_deflev integer yes t net.inet6.ipsec6.esp_trans_deflev integer yes t net.inet6.ipsec6.esp_net_deflev integer yes t net.inet6.ipsec6.ah_trans_deflev integer yes t net.inet6.ipsec6.ah_net_deflev integer yes .El
p They are 1:use or 2:require.
p 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. l -column net.inet6.ipsec6.def_policy integerxxx t Sy Name Type Changeable t net.inet.ipsec.def_policy integer yes t net.inet6.ipsec6.def_policy integer yes .El
p
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 icmp6 4 ,
.Xr intro 4 ,
.Xr ip6 4 ,
.Xr setkey 8 ,
.Xr sysctl 8 ,
.Xr racoon 8
p .Rs .%A Daniel L. McDonald .%A Craig Metz .%A Bao G. Phan .%T "PF_KEY Key Management API, Version 2" .%R RFC .%N 2367 .Re .Rs .%A "D. L. McDonald" .%T "A Simple IP Security API Extension to BSD Sockets" .%R internet draft .%N "draft-mcdonald-simple-ipsec-api-03.txt" .%O work in progress material .Re .Sh CAVEAT The IPsec support is subject to change as the IPsec protocols develop.
p
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.
Indexes created Mon Oct 13 00:09:54 GMT 2025