Bridge serial ppp0 to eth0
 

Unlike most of the the threads relating to this, I'm not trying to connect a local network on eth0 to the internet on ppp0, but rather the opposite; I have a computer which connects to the internet through my router on eth0, and another computer that connects to the first via a serial cable (ppp0). I know that brctl can't handle ppp0, and I am clueless about iptables, so I was wondering if anyone could tell me how to forward all packets (or even better, just the ones going to it) to the computer connected via serial cable. I don't really need IP masquerading, as it will be connected through my home router, which does this job. Any advice is much appreciated.

can you fill us in a bit on the topology here? this ppp0 link is meant to be a different subnet i take it, it being a serial link, that's be the norm. looks most like you'd just want to enable routing on the box in the middle and apply relevant routes to know what lives on the ppp link.

The ppp0 link isn't meant to be a different subnet, I basically just want to bridge it to eth0. I can't use brctl, and if I have to use iptables or something similar, I'd rather it just forward packets which are destined to one of the two IP addresses which will be connected through the serial link.

Topology:

ok well doing it by the book, google suggests that you'd need BCP support within pppd and the kernel, somethign not included by default, so you'd need a patch applying to your current kernel. most references to this are from 2005 though, so could have come in mainline since then on the kernel side at least. have a good look around i guess...

Is there some other way to get it to connect to the network, such as iptables or IP masquerading? I'd rather not recompile the kernel.

well iptables isn't going to help you do bridging. it could allow you to use the linux server as a port forwarding point, or alternatively to use the box as a router between two seperate networks. fancy the idea of either of these? neither appear to actually do what you really want.

Setting it up as two separate networks with the box set up as a router would work for me, I think. I don't know anything about how I would have to set the IP addresses, and subnet info though. I'm sure I would also have to put this info into my existing router, also. The current network is 192.168.1.0, with subnet 255.255.255.0. Anyone have any advice? BTW, thanks very much for your help acid_kewpie.