Bridging two interfaces on Ubuntu (one wireless one wired)

Question

I have two network interfaces on a laptop running Ubuntu 12.04. The wired interface is plugged into a wirless router on the 192.168.0.0 network and then wireless interface is connected to an ad-hoc network on the 192.168.1.1 network.

I want to connect another machine to the wireless router and have the data be routed to the ad-hoc network. So the other machine will get an address like 192.168.0.4 and it should be able to send data to the ad-hoc network say to machine 192.168.1.100.

I've tried simply changing the /etc/network/interface text file, but I really don't know what I am doing there, and I tried installing some bridging software and that doesn't seam to help.

Any ideas? Thank you.

Answer 1

The problem with this setup is that your router can not route packets to the 192.168.1.0 network because it is not configured to forward packets to that network. I assume you have a standard home router such as Dlink, Netgear, Linksys, Belkin, and not a hardcore commercial CISCO router. What you need to do in order for another machine to reach the ad hoc device is to setup NAT masquerading using IPTABLES. Using NAT you will reach hosts in the 192.168.1.0 network, but only the ports that you specify. This is often referred to as port forwarding. Depending on the protocols you would to use, TCP,UDP etc the specific settings vary. Here is a good page that will get you started: http://linux.ardynet.com/ipmasq/ipmasq.php3