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1. Setting up an Ubuntu Wired/Wirless Router

TableOfContents

1.1. Preface

This article exists due a lack of concise information and easily followed instructions on the subject of setting up an wired and/or wireless Ubuntu router. It is intended for advanced users who have or would like to set up a dedicated Ubuntu installation acting as a router at home or in their office. The end result is a powerful router that can provide functionality similar to popular products (for example, the Linksys WRT54G).

2. Prerequisites

2.1. Broadband Connection

A broadband connection like a cable or DSL modem is required. Your broadband service provider must either provide the necessary information to configure your IP address statically or provide a dynamically assigned address via DHCP.

2.2. Router Hardware

You'll need a dedicated computer to act as the router. The computer can use old hardware and having the minimum requirements to install Ubuntu should suffice. The author of this article runs his router on a P3 600mhz processor with 256MB of RAM. You are encouraged use this as a server for other applications perhaps by installing postfix, apache, mysql, and/or samba. This guide recommends a server installation of Ubuntu, but there's no reason why a desktop installation wouldn't work. If you plan to be able to access the router remotely, install ssh before proceeding.

The following needs to be physically installed and recognized by the kernel on your router:

• A network adapter connected to the broadband cable or DSL modem

• For a wired network,

  • Another network adapter connected to a hub or switch

• For a wireless network,

  • A wireless network adapter (which must be able to be set in "master" mode)

    • If your wireless network adapter is not recognized by your server installation of Ubuntu, it may use the madwifi chipset (like the D-Link DWL-G520). Please visit ["Router/Madwifi"] for more information.

• For both a wired and wireless network,

  • All of the above

3. Internal Network Information

Here are the values we'll use to set up your internal network. Advanced users use caution when changing them as the changes will need to be reflected in all further router configuration.

4. Setting Up Your Network Interfaces

4.1. Device Naming Overview

It is important to note that the names of the network devices above (eth0, eth1, and wlan0) are used as convention. It is very likely that your router will recognize its devices under different names (for example, madwifi calls its wireless device ath0). Please substitute the names of your device accordingly. For information about how to change the names of your network devices, try man iftab.

4.2. Taking a Backup

Issue the following command to take a backup of your current network configuration: {{{sudo cp /etc/network/interfaces /etc/network/interfaces.bak }}}

4.3. Configuring External Network Interfaces

Here, we configure the Ubuntu networking system to bring the the local loopback and external network interfaces up by editing /etc/networking/interfaces.

4.3.1. For Static IP Address Only

Open /etc/network/interfaces with your favourite editor. Delete everything and paste in what is below. Follow the commented out instructions carefully.

{{{# Set up the local loopback interface auto lo iface lo inet loopback

# Set up the Exte interface # # For every xxx.xxx.xxx.xxx, enter the numeric address given to you # by your Internet provider. Don't forget to change eth0 to the proper # name of the WAN interface if applicable. # auto eth0 iface eth0 inet static

• address xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx gateway xxx.xxx.xxx.xxx}}}

Now, set up your DNS servers as given to you by your service provider in /etc/resolv.conf, which should look something like this {{{nameserver xxx.xxx.xxx.xxx nameserver xxx.xxx.xxx.xxx}}}

Restart networking with the following command: {{{sudo /etc/init.d/networking restart }}}

4.3.2. For Dynamic IP Addresses (DHCP) Only

Open /etc/network/interfaces with your favourite editor. Delete everything and paste in what is below. Follow the commented out instructions carefully.

{{{# Set up the local loopback interface auto lo iface lo inet loopback

# Set up the external interface # # Don't forget to change eth0 to the proper name of the external # interface if applicable. # auto eth0 iface eth0 inet dhcp}}}

Restart networking with the following command: {{{sudo /etc/init.d/networking restart }}}

4.3.3. More Information

Further editing of /etc/network/interfaces may be needed to set up PPPoE networking. Try the article ["ADSLPPPoE"] for more information.

4.4. Configuring Internal Network Interfaces

4.4.1. Wired Only

Append the following to /etc/network/interfaces and follow the commented out instructions carefully. {{{# Set up the internal wired network # # Don't forget to change eth1 to the proper name of the internal # network interface if applicable. # auto eth1 iface eth1 inet static

• address 192.168.0.1 network 192.168.0.0 netmask 255.255.255.0 broadcast 192.168.0.255}}}

4.4.2. Wireless Only

4.4.3. Both Wired and Wireless