Help with IP Tables

jbar25 · n00b Joined: 15 Aug 2006 Posts: 2

Hi I am using multiple networks(nics) on my server at home. I am planning to use my primay ISP as my main traffic line and I am planning to use a wireless network to handle certain types of traffic traveling over certain port protocols. I am trying to find some help writing a generic ip tables script that will tell the kernel to route traffic from this range of ports over wlan0 and all other protocols over eth0. Has anyone here ever done this? Any help would be greatly appreciated. I have been searching google and the only thing that I can find that would help me out any looks like the MANGLE command for marking packets, but I am still unsure of how to tell IP tables to route this properly.

pteppic · l33t Joined: 28 Nov 2005 Posts: 781

The question is a little vague and I don't want to send you in the wrong direction, can you give a specific network configuration and application as an example please.

jbar25 · n00b Joined: 15 Aug 2006 Posts: 2

I have two ISP's. One is wireless and one is hardwired. Basically I want my bandwidth consuming apps, such as bittorrent and ftp, to be routed across one isp (wireless wlan0) and all of my regular internet usage traffic to go over my other ISP (wired eth0 cable modem) But I would like for IP Tables to do the routing by port protocol. Such as all inbound and outbound traffic on port 21 and 6881-7000 to go through wlan0 and all other traffic * to go through eth0. I already have everything setup as far as applications and hardware are concerned but I am having trouble writing a script because I dont know where to begin on advanced routing. Thanks for any help.

pteppic · l33t Joined: 28 Nov 2005 Posts: 781

Right, this is a very tenious description of what you have to do, I understand it in principle only.
Use iptables mangle tables to mark the outgoing packets, then (using iproute2) pick up on that mark and use a custom routing table for them.

This seems to give you the best starting point http://www.tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.netfilter.html

I'm quite interested in your results, and would be happy to setup a 'test environment' at this end in VMWare if you have too much trouble (have a redundant ADSL connection laying around idle I may make use of until 'they' stop paying for it :wink:

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