DIY Networks - Example Wireless Router Configuration

Configuring a Linksys WRT54GL Wireless Router

We have chosen the Linksys WRT54GL as an example for our wireless router configuration tutorial because it is a common and widely available wireless router. Generally the build quality on these routers is excellent and they provide a reliable and affordable backbone to your wireless network.

For our example we shall configure the router so that it can be connected to an ADSL modem and used to distribute an ADSL internet connection throughout the location where it is used. This configuration is quite acceptable for home or office use. If you examine our diagram to the right of this paragraph you can see that this network has two segments, 192.168.1.1 is the modem's IP address and the routers WAN or Wide Area Network port has an address of 192.168.1.20. The Local Area Network or LAN interface on the router is on a different network with an IP address of 192.168.2.1 and all of the client computers that connect to the router have an IP address in the 192.168.2.X range.

This really illustrates the difference between an access point and a router. An access point will generally have one ethernet port which allows it to connect to a wired or ethernet network and really only serves as a bridge between a wireless network and a wired network. A router on the other hand seperates the LAN from the wired network it is connected to via its WAN port and routes packets of data to either the WAN or the LAN depending on its intended destination. Most routers, the linksys included, have built in firewalls for extra security and most also have ethernet ports as well, the linksys has four. This allows you to create a wireless and wired network combined and safely protected by the routers firewall whilst still being able to share files and printers etc.

The Web Interface

Virtually all devices such as routers, access points, adsl modems etc are configured via a web interface. A web interface is really just a web page that the device displays that you can change configuration values in so that your device works properly. Many of them have other methods as well such as set up CD's that use Plug'N'Play or even command line interfaces. We shall focus on the WRT54GL's web interface as it is a common thread and will allow us to illustrate how one of these devices can be configured.

To access our routers web interface we must turn it on and connect a computer to it somehow. Generally an ethernet connection is the best way but many wireless routers are configured as open networks when they are manufactured so you can connect to them wirelessly. You may need to consult your routers manual or online documentation to find out what IP address is configured on it when it leaves the factory. Our WRT54GL has a factory LAN IP address of 192.168.1.1 and subnet mask of 255.255.255.0. Its DHCP server is enabled by default, so it is quite possible to plug the computer into a LAN port with an ethernet cable, receive an IP address by DHCP and simply log into it. If you have to manually specify an IP address as shown on the ethernet configuration page then anything in the 192.168.1.X address space will be fine, say 192.168.1.10 with a subnet mask of 255.255.255.0.

Log into the router via its web interface Now that we have established connectivity between the router and our computer we need to log into the web interface and start configuring it. Open your web browser (eg Internet Explorer, Firefox, Opera, Safari or whatever you prefer) and into the address field type the routers IP address, in our example its 192.168.1.1 . Some browsers may require you to type http://192.168.1.1. A box will pop up in the centre of the screen asking for a username and password. Most of the time on most factory default devices it is simply admin for the username and admin for the password. Consult your devices manual if this is not the case with your router.

Once you have successfully logged into your router you will be presented with the WRT54GL basic configuration page. The configuration options on this page include very important options such as internet connection type, the local area network (LAN) IP address and subnet mask and dynamic host configuration protocol (DHCP) settings. The different options on this page must be configured to suit your network or things simply wont work as expected or possibly not at all.

Internet Connection Type

The first section of the WRT54GL setup page is the internet connection type. If you examine our network diagram at the top of this page you can see that the ADSL modem that this router will connect to has an IP address of 192.168.1.1. The WRT54GL router will connect to the modem with a cable directly from its wide area network (WAN) port into one of the LAN ports of the modem. The default setting is DHCP, where it will get its address automatically from the modem and this is quite acceptable too. We shall use a fixed IP address because it will be slightly more robust than DHCP in the event of a cable being unplugged or an issue with the DHCP server of the modem. The internet IP address or WAN IP is set to 192.168.1.20 with a subnet mask of 255.255.255.0. The gateway address is the address of the ADSL modem, 192.168.1.1, so that the router knows that this is where to send packets of data that are destined for the internet. Nameservers supplied to us by our ISP fill in the Static DNS fields, our ISP only has two so the third one is left blank.