Crosslinking WAN connections?

Nefarious · 21 Aug 2008 at 01:27

Does anyone know if it's possible/good tutorials on how to get a Debian proxy server to cross link two internet connections?

If I was being lazy, I'd just route all port 80 through one and everything else through another, but if there was something more fun, I'd like to know about it.

Thanks

daz.rathbone · 21 Aug 2008 at 08:53

Not sure I follow the "cross link" term.

If you mean is it possible to load balance dual WAN ports, then yes it is. I'd recommend having a look at Shorewall. Lots of good tutorials out there, but it is a bit of a "grey" science. The difficulty isn't in load-balancing the traffic over 2 different WAN ports, which can be achieved by a simple round-robin method, it's in ensuring the sessions (for want of a better word) stay in-tact. If you connect to a web application from IP Provider A, then the next data you send is from IP Provider B, the app will not maintain session info (this is a VERy simplified explanation, not a good one, sorry).

Nefarious · 28 Aug 2008 at 13:24

Yes, that is what I meant and I did rather think that might be the problem - will have a look at the things you suggested but looks like the port 80 traffic splitting might be the best solution.

Thanks

Nefarious · 28 Aug 2008 at 13:40

Hmm, had a look at Shorewall - I only gave it a brief glance but it seemed to be more for configuring firewalls than selectively routing packets but will read on.

As a thought... would load balancing allow a server to have several network cards and increase speeds that way rather than having a gigabit with switch?

daz.rathbone · 28 Aug 2008 at 21:18

It could do, but your best bet for that is to look into Ethernet "bonding".

Shorewall is a firewall/router - it does both, though obviously you could configure the firewall element to do nowt if required. There's a few other things about, mostly rules using iptables (which is actually what shorewall does anyway) that create persistent states over connections. I did a LOT of googling for this before, but decided the simplest route would probably be to get a router that supported dual-WAN load-balancing (there are a few).