How do I connect a LAN to a WLAN through a server?

Gav · n00b Joined: 10 Oct 2002 Posts: 65 Location: Surrey, UK

Soon, I'm moving and will be accessing the internet through a wireless router. Unfortunatly I have several PCs and I don't want to get a wireless card for them all. I want to use my server to go from the wireless part of the network to the wired that I already have. I'm happy to keep it all in one subnet. Reading around I'm not sure if bridging is the term or not. Should it be routing, or be referred to as an access point or something else?

Here's my diagram of how things will be (why won't it show inline?)

There's the router, a single PC wired to it. Then the server needs to connect wirelessly and then connect to the other PCs. The server runs all sorts of stuff so needs to be accesible (by a fixed IP). It runs Gentoo of course, as do a couple of desktop's that will need to connect through it and to it.

So, what's the right term for what I want to do? I can look up what I need to do knowing what it is. Can bridging do this, by setting up a single IP (ie non-transparent) for both the server's network interfaces (1 wired, 1 wireless)? I don't mind about changing gateway addresses and other config stuff on each PC, since there's only a few.

pmjdebruijn · Posted: Fri Jul 23, 2004 3:15 pm Post subject:

Well... I think this probably can be solved easily

Just add a supported Wireless card (Intersil Prism or the likes) into the server.

Then do this:
echo 1 > /proc/sys/net/ipv4/ip_forward

or add to sysctl.conf:
sys.net.ipv4.ip_forward = 1

And DO keep everything in one subnet....

I think this should do it!

Your linux server now should recognize that any packet on the wireless card is destined for a pc and forward it... At least theoritically. You'll have to try.

Good luck,
Pascal de Bruijn

barlad · l33t Joined: 22 Feb 2003 Posts: 673

Hmm are you sure? As far as I know, ip_forwarding is useful when you are doing some routing but here we do not need a router since everything is on the same subnet (only level 2 operations are required).

I think what you are looking for is exactly what you said: bridging. Your server will have to act as a bridge between the Wireless AP + the PC linked to it and the rest of the network. So bridge the two interfaces of the server using br tools, assign one ip to the "bridge" and you are set.

pmjdebruijn · Posted: Fri Jul 23, 2004 4:40 pm Post subject:

Well, i wasn't really sure...

Now thinking of it... bridging seems better applicable indeed.

Just don't forget to compiled in the kernel module....

btw, Gav if you succeed, would you mind posting the commands you used to set it up here... for other to use...

Good luck,
Pascal de Bruijn