It’s a little known fact that the fimware on Linksys routers is open-source. In fact, the operating system on WRT54G’s version 4 and below is Linux. Some time ago, people took advantage of this and made their own replacement firmware images for their routers. Once the non-Linux version 5 routers were released, Cisco saw the demand for a Linux version again and released the WRT54GL, so that third-party firmware could be used again.