[SATLUG] Routing from one box to two different ISPs

[Daniel J. Givens]

On Thu, 5 Apr 2007 12:29:31 -0500, "David Salisbury" <david.salisbury at momentumweb.com> wrote:
> I'm trying to get something working on a Linux box that I have, and so far
> no luck.  Basically I have a box with two NICs and two different providers,
> one for each NIC (Cable and DSL, say).  Both have static IPs and can be
> pinged successfully from elsewhere in the world.  However, if I try to
> access a web server I have running on the box (which IS bound to each
> interface in the web server conf), it works over the DSL interface (eth0)
> but not the RR one (eth1).

Chances are, RR is blocking port 80 inbound. You'll probably find that 25 is also blocked outbound to anything other than their SMTP servers. If you want to email me directly with your IP, I'll do a port scan on you and send you the results.

If all you want is a fail-over connection, then you would setup two default gateways, with one having a lower metric than the other. The lower metric would mean that connection would be "preferred". In theory, if you setup both default gateways with the same metric, you would get round-robin load balanced routing. You could try that or try GNU/Zebra[1]. I tried something similar a while back, but that was just for using two outbound connections. 

One thing you might try, assuming port 80 inbound is allowed on RR, is to setup round robin DNS. That would be the only real way you could get load balancing unless you had some sort of routing protocol action going on with your ISPs. Basically, the rest of the Internet would need to know how to get to your network through all of your ISPs. The best you can hope for is load balanced inbound connection using round robin DNS and load balanced outbound connections through round robin routing.