(usagi-users 03681) Kernel hacking: IPv6 autoconfiguration and forwarding at the same time

[Michal Martinek <michal.martinek@xxxxxxxxxxx>]

Hello all,

I' like to ask you what changes needs to be done in kernel sources (2.6.16 at best) in order to have 
IPv6 autoconfiguration working (i.e. accepting Router Advertisements, sending Router Solicitations) 
even when the IPv6 forwarding is on. From the discussion from some time ago, I've learned the the 
"ndisc_router_discovery" function in "net/ipv6/ndisc.c" needs to be changed. Are there any other 
files that should be changed?

I don't want to start again the discussion of why the router should not accept RA messages, so I'd 
like to explain my motivation:
We would like to have a router that is able (along with its whole subnet) to automatically migrate 
between different networks (e.g. different ISPs) when moving from one place to another. So the 
router must be able to dynamically change its outbound address using the prefix provided by the new 
ISP. I know that this problem should be solved by using Router Renumbering (RFC2894), but since I 
don't know any implementation of it for Linux, changing the kernel the way I described seems to me 
as the simplest way to achieve our goal.

If you have any "cleaner" ideas of how to automatically change the router address without hacking 
the kernel, please send it to me. I'd be thankful for any advice.

Thanks in advance,

Michal