4th Mar 2001, Pekka Savola <pekkas@netcore.fi>


HOW TO SET UP AN IPV6 TUNNEL
----------------------------

ASSUMPTIONS
-----------

1. You're running Red Hat Linux 7.1 or later.
   
   This is required for correct IPv6 by default settings, and IPv6 being
   enabled as a kernel module by default.  You also need recent enough
   initscripts, provided in RHL71.

2. You have a static, globally unique IPv4 address.

3. Protocol 41 (IPv6) is not being filtered in any firewall.


INFORMATION NEEDED
------------------

You need to know:

1. The IPv4 address of your tunnel end point
2. The IPv6 address used in your tunnel

The other end needs to know the same things about your setup.

NOTE: It is also possible to set up unnumbered tunnels (no global IPv6
addresses).

You must get these from a party (tunnel broker) who's assigning IPv6 tunnels.  See:
http://www.bieringer.de/linux/IPv6/IPv6-HOWTO/IPv6-HOWTO-1.html#joinIPv6backbone

Example from http://www.freenet6.net:
---
This script will create a tunnel between this computer
and the Freenet6 server (tunnels server)
Your IPv6 address (your tunnel end point) is
3ffe:b00:c18:1fff:0:0:0:7f5 
We establish a tunnel to the Freenet6 server at
3ffe:b00:c18:1fff:0:0:0:7f4 
Your IPv4 address is : 193.xxx.yyy.zzz 
The IPv4 address of the Freenet6 server is : 206.123.31.102 
---

With this information, a tunnel can be set up:

SETTING UP THE TUNNEL CONFIGURATION
-----------------------------------

Now, set up the configuration as follows:

1. Add 'NETWORKING_IPV6=yes' to /etc/sysconfig/network:

   echo "NETWORKING_IPV6=yes" >> /etc/sysconfig/network

2. Add static routes to IPv6 Internet:

   echo "sit1	3ffe::/16" >>  /etc/sysconfig/static-routes-ipv6
   echo "sit1	2000::/3" >>  /etc/sysconfig/static-routes-ipv6

3. Create /etc/sysconfig/network-scripts/ifcfg-sit1, with the following:

---
DEVICE=sit1
BOOTPROTO=none
ONBOOT=yes
IPV6INIT=yes
IPV6TUNNELIPV4=206.123.31.102
IPV6ADDR=3ffe:b00:c18:1fff:0:0:0:7f5/0
---

NOTE: You must use _sit1_.  sit0 should not be used.

NOTE: You must use prefix /0, else you may not be able to ping your P-t-P
peer without tweaking.

NOTE: If you're not directly connected to the Internet, you may want to use
ONBOOT=no instead.

TUNNELING
---------

Tunnel can be brought up and down with:

   ifup sit1
   ifdown sit1

NOTE: Even though sit1 is used, 'ifconfig' sees the tunnel as sit0.  This
is due to an "interesting" implementation of tunneling -- else multiple
tunnels couldn't be used extensibly.

MORE INFORMATION
----------------

http://www.bieringer.de/linux/IPv6/IPv6-HOWTO/IPv6-HOWTO.html is a good
source of IPv6 related Linux-information.