Unleash the Hidden Features Using DD-WRT

Overview

Linksys WRT54G router is capable of working in repeater mode with third party firmware like DD-WRT. A WiFi repeater is a device that will connect to another wireless access point and redistribute the signal. Repeaters are typically used to extend the coverage of a network in office buildings, hotels, convention halls, airports and other public spaces.

Repeaters can also be used on a smaller scale to share an internet connection with a neighbor. You can also use a repeater to set up a communal open hotspot and share the connection with a group of neighbors.

Installing DD-WRT

As of June 2007, DD-WRT beta v24 firmware is the only version that works in repeater mode. You can download it here. The download area is a bit confusing. Follow these steps to find the correct firmware:

1. select “beta”
2. select “GENERIC BROADCOM”
3. select “dd-wrt.v24 beta”
4. select the most current date

This last step will take you to a folder full of different versions of the firmware. You will need one or more files marked as “WRT54G.” To determine which one is appropriate for your version of WRT54G you need to consult the wiki. Some of the more recent versions of WRT54G have a RAM issue that can be overcome by installing the smaller “micro” version.

DD-WRT firmware is relatively easy to install and setup. The installation process varies slightly based on the version of the router you have. The older WRT54G models you can buy used on Ebay are better candidates for third party firmware installation.

Linksys has moved away from open source firmware in the new models of WRT54G. However, the current WRT54GL will still accept third party firmware. Not surprisingly, this model costs more than comparable units so stick to the used stuff when you can.

The official DD-WRT page is the best place to get installation instructions. There is some useful information in the wiki. The DD-WRT forum is better than the wiki although both presuppose you have basic networking skills. I had none prior to doing all this and still made it through. You can too.

A word about “bricked” routers

A “bricked” router is a malfunctioning router. It’s as usefull for networking as a brick. This is typically a result of a bad firmware flash. It is possible to recover a “bricked” device in most cases but there are varying degrees of difficulty. To avoid bricking always follow instructions carefully.

There are times when you may have to use TFTP to flash the router. If your operating system does not support TFTP you can download a free Linksys TFTP utility. It is very easy to use and has saved me several times.

A “bricked” router is a malfunctioning router. It’s as useful for networking as a brick. This is typically a result of a bad firmware flash. It is possible to recover a “bricked” device in most cases but there are varying degrees of difficulty. Always follow instructions carefully.

Setting up the repeater mode

A very good guide by Aaron Weiss with step by step instructions and screen captures is provided here.

Several sources claim that although you can increase the transmit power to 250mW the practical limit is around 82mW. Anything beyond increases the noise in the signal. I’m currently operating at 92mW for testing purposes and it seems to work fine. There may be some legal considerations regarding signal strength depending on the country you live in. In the United States FCC regulates such matters.

I have noticed that WRT54GL is not as sensitive as my Buffalo PCMCIA wireless card. At any time I can see more networks with my card than I can with the router. I suspect that this is just how the things are with the hardware that Linksys uses.

Based on observation the connection speed when in repeater mode is roughly a half of what I can get connecting to the source network directly. This makes sense to me but I have seen writings that claim that this should not be the case with repeaters.

External antennas may be very useful depending on your configuration. Using two different antennas on WRT54G i.e. a directional antenna and an omni-directional antenna is not recommended. It may decrease reliability of connection due to multipath distortion. However, it may be worth a try. I have a working system with two different antennas.

Netstumbler is excellent free software for troubleshooting spotty signal coverage and antenna positioning.