Source: http://www.pcmag.com/article2/0,1759,1772504,00.asp
Turbocharge Your Linksys Access Point By Lee Barken Did you know that the popular Linksys WRT54G Wireless Broadband Router--that small blue and black device that provides wireless Internet access to so many home and small-business networks--is actually a complete little computer running a specialized version of embedded Linux as its operating system? And because portions of the WRT54G code are protected under the open-source GPL software license, Linksys is obligated to make the source code available to the public (for more details, see www.linksys.com/support/gpl.asp ). Not surprisingly, this has attracted the attention of tinkerers and enthusiasts everywhere. Numerous efforts have gone into modifying and improving the code to add features and enhance capability. As a result, many shortcomings of the Linksys firmware (v. 3.01.3 as of this writing) have been overcome. Sveasoft's Satori, probably the most popular firmware enhancement, adds about 30 new features to the standard WRT54G menus. For example, let's say you wanted to connect a more powerful directional antenna to one of the external antenna ports. To function properly, the access point (AP) would need to disable Diversity mode and use one of the antenna connections for both transmit and receive operations. What if you wanted to increase or decrease the power levels? Boosting power is desirable in some deployments because it increases your coverage area. Lowering power can be useful if you want to limit RF overflow into the parking lot for security purposes, or perhaps to deploy a high density of APs in a smaller area in order to support a larger number of clients. Imagine if you could open a secure shell (SSH) and explore the Linksys file system! All of these things and more are possible using Satori (and other third-party firmware upgrades for the WRT54G). Getting the Firmware Satori can be downloaded free from the Downloads section of www.linksysinfo.org . Once you've downloaded the distribution, upgrading your AP is a simple procedure using the built-in Web interface. Just open a Web browser and point it to your AP's IP address. By default, it will be http://192.168.1.1. Linksys strongly recommends that you perform firmware upgrades using a wired (not wireless) connection, so if you're not already hooked up, dust off an old Cat 5 cable and connect it between your computer and the AP. At the WRT54G log-on, the username should be blank, and the default password is admin (but of course you've changed your password from the default!). Click on OK, then click on the Administration | Firmware Upgrade tab. Browse to your new firmware and then click on Upgrade. After a minute or two, you should receive a message indicating that the upload was successful. If you experience problems, you can try to reset to factory defaults by holding the reset button for 30 seconds. Keep in mind that the factory-default firmware might not be the latest version. Check the Linksys Web site if you want the most recent version of the stock Linksys firmware. Also, you'll find a special WRT54G revival page at http://voidmain.is-a-geek.net/redhat/wrt54g_revival.html . In any case, all your settings should still be there: They are kept in NVRAM, not firmware. Exploring New Features We installed Satori on our router without any problems, and saw several new features in the browser-based management interface. For example, the Wireless | Advanced Settings tab has new options called TX Antenna and RX Antenna, which let us select the right or left antenna as our main transmit or receive antenna (instead of using Diversity mode). In addition, the Xmit Power option lets us change our power output level. Be careful to observe all FCC regulations when modifying power output levels and adding external antennas. We also noticed new support for Wireless Distribution System (WDS) in the Wireless | WDS tab. WDS, which lets you add another access point for more coverage, is not supported in the stock Linksys firmware. If you really want to get to the guts of your router, take a look at the Administration | Management tab, where we discovered the new SSHD option. When this feature is enabled, the router starts an SSH server, which lets you establish a remote secure shell into the device. After we selected SSHD and clicked on Save Settings, the screen refreshed, and we were presented with new choices which we could configure. We turned on Password Login and again saved settings, and then we were able to SSH into the Linksys device using a username of root and the device's password, which by default is set to admin. With an SSH shell established, we could get at the router's operating system and explore the entire file system. Once you have this root-level access, you are the system "superuser," and can make any changes to the system you desire. Happy hacking! Lee Barken is president of SoCalFreeNet.org and co-director of http://starcenter.sdsu.edu. He is a co-author of Wireless Hacking: Projects for Wi-Fi Enthusiasts (Syngress).
