#!/bin/bash
ip="/usr/sbin/ip"
IF1="eth0" #Interface connecting to provider 1
IF2="eth1.4" #Interface connecting to provider 2
IP1="213.40.81.180" #IP from provider 1
IP2="192.168.15.2" #IP from provider 2
P1="213.40.81.1" #GW of provider 1
P2="192.168.15.1" #GW of provider 2
P1_NET="213.40.81.0/24"
P2_NET="192.168.15.0/24"

#setup the routing tables
$ip route add $P1_NET dev $IF1 src $IP1 table T1
$ip route add default via $P1 table d3
$ip route add $P2_NET dev $IF2 src $IP2 table T2 
$ip route add default via $P2 table btk

#automagically exist
#$ip route add $P1_NET dev $IF1 src $IP1
#$ip route add $P2_NET dev $IF2 src $IP2

#Answers shuld be sent through the same interface,
#	where requests came in from.
$ip rule add from $IP1 lookup T1
$ip rule add from $IP2 table T2

#here is routing for individual clients
#In this example 10.10.240.0/22 is routed through provider 1
#and 10.0.0.0/8 through provider 2
$ip rule add from 10.0.0.0/8 table T2
$ip rule add from 83.229.68.236/30 table T1
$ip rule add from 10.10.240.0/22 table T1

$ip route add default via $P2 table default #prefered default gateway

#Prefer the main table, but there sould be no default route
$ip route del default table main &> /dev/null
$ip rule del from all lookup main
$ip rule add from all lookup main