Subject: Any source-based IP routing solutions availiable?
To: None <tech-net@NetBSD.ORG>
From: Martin Cracauer <>
List: tech-net
Date: 01/05/1996 10:16:25
A friend of mine needs to do source-based IP routing. For now, he uses
a hacked Linux IP stack, because the functionality he needs isn't
included in any stack we know and that the Linux stack is (claimed to
be) significant easier to hack up to do the job than the more complex
*BSD one.

Is there any solution for this problem in 4.4BSD?

Here's what to be done: A single machine is a router for a number of
client networks and is connected to more than one provider. Every
client network is associated with exactly one provider and this
provider should be the default route for packets from this client's

The problem is that in the code regions where the decision about the
route a packet has to be sent to is made no information about the
source of the packet is available. A local Linux hacker hacked the
Linux stack so that the source address is passed along with the
destination address and he claims is would be too much work in the BSD
kernel, simply because of the number of function calls that have to be

I think this is a quite common problem for ISPs and even for me who
passes packets from other networks on my private machines and I wonder
if some BSD based solution is already done.

Thanks for any hints.

Happy Hacking
Martin Cracauer <>  
Tel.: +49 40 / 522 18 29
Fax.: +49 40 / 522 85 36