Linux Advanced Routing & Traffic Control HOWTO

This document hopes to enlighten you on how to do more with Linux 2.2/2.4 routing. Unbeknownst to most users, you already run tools which allow you to do spectacular things. Commands like route and ifconfig are actually very thin wrappers for the very powerful iproute2 infrastructure.

I hope that this HOWTO will become as readable as the ones by Rusty Russell of (amongst other things) netfilter fame.

You can always reach us by posting to the mailing list (see the relevant section) if you have comments or questions about or somewhat related to this HOWTO. We are no free helpdesk, but we often will answer questions asked on the list.

Before losing your way in this HOWTO, if all you want to do is simple traffic shaping, skip everything and head to the Other possibilities chapter, and read about CBQ.init.

What Linux can do for you

A small list of things that are possible:

• Throttle bandwidth for certain computers
• Throttle bandwidth TO certain computers
• Help you to fairly share your bandwidth
• Protect your network from DoS attacks
• Protect the Internet from your customers
• Multiplex several servers as one, for load balancing or enhanced availability
• Restrict access to your computers
• Limit access of your users to other hosts
• Do routing based on user id (yes!), MAC address, source IP address, port, type of service, time of day, or content

Currently, not many people are using these advanced features. This is for several reasons. While the provided documentation is verbose, it is not very hands-on. Traffic control is almost undocumented.