[src/trunk]: src/share/man/man4 A manpage for the ipip pseudo-device.

[hwr <hwr%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c95a8aa1acc0
branches:  trunk
changeset: 467742:c95a8aa1acc0
user:      hwr <hwr%NetBSD.org@localhost>
date:      Sun Mar 28 17:05:18 1999 +0000

description:
A manpage for the ipip pseudo-device.

diffstat:

 share/man/man4/ipip.4 |  141 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 141 insertions(+), 0 deletions(-)

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+.\" $NetBSD: ipip.4,v 1.1 1999/03/28 17:05:18 hwr Exp $
+.\"
+.\" Copyright 1998 (c) The NetBSD Foundation, Inc.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software contributed to The NetBSD Foundation
+.\" by Heiko W.Rupp <hwr%pilhuhn.de@localhost>
+.\"
+.\" 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 the NetBSD
+.\"    Foundation, Inc. and its contributors.
+.\" 4. Neither the name of the The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+.\"
+.Dd 28 March 1999
+.Dt IPIP 4
+.Os 
+.Sh NAME
+.Nm ipip
+.Nd encapsulating network device
+.Sh SYNOPSIS
+.Cd pseudo-device ipip Op Ar count
+.Sh DESCRIPTION
+The
+.Nm ipip
+network interface is a pseudo device that allows to encapsulate datagrams
+into IP. These encapsulated datagrams are routed to a destination host,
+where they are decapsulated and further routed to their final destination.
+The so called ``tunnel'' appears to the inner datagrams like one hop.
+Encapsulation is according to RFC 2003. The outer datagram header is of
+IP type 4 (IPIP).
+.Pp
+The network interfaces are named
+.Sy ipip Ns Ar 0 ,
+.Sy ipip Ns Ar 1 
+and so on, as many as have given on the 
+.Sy pseudo-device
+line in the system config file.
+.Pp
+Note that the IP addresses of the tunnel endpoints may be the same as the
+ones defined with 
+.Xr ifconfig
+for the interface (as if IP is encapsulated), but need not be.
+.Pp
+.Sh EXAMPLE
+Configuration example:
+
+
+Host X-- Host A  ----------------tunnel---------- cisco D------Host E
+          \\                                          |
+           \\                                        /
+             +------Host B----------Host C----------+
+
+   On host A (NetBSD):
+
+   # route add default B
+   # ifconfig ipipN  A D netmask 0xffffffff  up
+   # route add E D
+
+   On Host D (Cisco):
+
+   Interface TunnelX   
+    ip unnumbered D   ! e.g. address from ethernet interface
+    tunnel source D   ! e.g. address from ethernet interface
+    tunnel destination A
+   ip route C <some interface and mask>
+   ip route A mask C
+   ip route X mask tunnelX
+
+   OR
+
+   On Host D (NetBSD):
+
+   # route add default C
+   # ifconfig ipipN D A 
+.Pp
+If all goes well, you should see packets flowing ;-)
+.Pp
+If you want to reach Host A over the tunnel (from the Cisco D), then 
+you have to have an alias on Host A for e.g. the ethernet interface like:
+     ifconfig <etherif> alias Y
+ and on the cisco
+     ip route Y mask tunnelX
+.Sh NOTE
+For correct operation, the
+.Nm
+device needs a route to the destination, that is less specific than the
+one over the tunnel.
+(Basically, there needs to be a route to the decapsulating host that
+does not run over the tunnel, as this would be a loop ..)
+.Pp
+In order to 
+.Xr ifconfig
+to actually mark the interface as up, the keyword ``up'' must be given
+last on its command line.
+.Pp
+The kernel must be set to forward datagrams by either option
+``GATEWAY'' in the kernel config file or by issuing the appropriate 
+option to
+.Xr sysctl .
+.Sh SEE ALSO
+.Xr netintro 4 ,
+.Xr ip 4 ,
+.Xr gre 4 ,
+.Xr atalk 4 ,
+.Xr inet 4 ,
+.Xr ifconfig 8 ,
+.Xr options 4 ,
+.Xr protocols 5 ,
+.Xr sysctl 8
+.Pp
+A description of IPIP encapsulation can be found in RFC 2003.
+.Sh BUGS
+The ipip_compute_route() code in ip_ipip.c toggles the last bit of the
+IP-address to provoke the search for a less specific route than the
+one directly over the tunnel to prevent loops. This is possibly not
+the best solution.
+.Pp
+Traceroute does not work yet over the tunnel :(