Load balancing with a script in linux

When you have two ISPs you may want to make your linux machine balance the load of your internet access, you can use ip route

The package needed for this is iproute, if you are using debian you can install it with

apt-get install iproute

or go to this page and download the source of iproute

Let's use this Load Balance Script which work for Centos, Fedora, Ubuntu, Debian and should work for all distributions.

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#!/bin/bash

#IPs of the def gateways

IP1=192.168.1.1

IP2=192.168.2.1

REDLOCAL=10.1.1.0/24

IPLOCAL=10.1.1.1

# NICs

IF1=eth0

IF2=eth1

ip rule add from $IP1 lookup T1

ip route add $REDLOCAL via $IPLOCAL table T1

ip route add 0/0 via $IP1 table T1

ip route add from $IP2 lookup T2

ip route add $REDLOCAL via $IPLOCAL table T2

ip route add 0/0 via $IP1 table T1

ip route default equalize nexthop via $IP1 dev $IF1 nexthop via $IP2 dev $IF2

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that should do the job, off course make the changes on the variables according to your needs.