Multiple ISP connections through router

[Simba7]

I have 3 ISP's, Optimum, CenturyLink, and Verizon. The issue is, how do I get my router to talk to all of them? They all get their IP's via DHCP, so static is not an option.

The gateways are:

Optimum (via eth1): 174.45.232.1
CenturyLink (via ppp0): 67.42.227.201
Verizon (via eth3): 192.168.254.1

I have iproute2 installed, but can't find a definitive answer due to me utilizing dynamic IPs.

[ponch]

dynamic is not a problem.
just write script to update routing tables via ip-up (for ppp) and dhcp-hooks. For every ip renew - flush old and add new rules.

[thegeezer]

http://lartc.org/howto/lartc.rpdb.multiple-links.html

the basic principal is one ethernet per link
use iptables mangle to mark A,B, or C on incoming connections

do not mangle-mark the internal LAN

have 3 routing tables, one for each link -- basically the difference in each is the default gateway

then you need
ip rule mark A lookup tableA to have replies go back via the way they came in.

so the question is, which route do you take by default?

you can set by anything, i.e.
ip rule from myPC lookup tableA
ip rule from myMissusPC lookup tableB

or even iptables mangle mark based on protocol etc