DD-WRT is an open source router firmware based on Linux. The open source community realised that Linksys had used GPL licenced code to build the firmware of their WRT54 home market routers. The community partitioned Linksys to release the software code they had written in order to compile with the terms of the GPL.

Unusually, Linksys open sourced all the software and not just the sections which used the GPL licence, and thus the DD-WRT project was born. It's aim is to turn a £60 router into a £600 router, for as many routers as it can.

DD-WRT's website has thousands of pages of documentation, but it seems to be lacking the bit which tells you how and where to get the bit you want. So here it is. The instructions below tell you how to find out which version you need to download for your particular hardware type.

On the bottom of the router there is a panel which lists the model number and version. Goto the DD-WRT Supported Devices page and match the model to a Hardware type and hardware version.

1. Various sizing restrictions mean that on some routers you may not be able to install the full version so make a note of the DD-WRT version required column.
2. The File Version pages tells you what the file names mean. In most cases you want the standard version.
3. Go to DD-WRT's download area.
4. Choose whether you would like stable or release candidates: stable usually means 'the old version' and release candidate means 'newer, but a bit untested'. I usually go for a release candidate for the new features. If you feel the need you can report bugs back to the project.
5. Select the version number.
6. Earlier you made a note of the hardware type from the supported devices list, so select that type now.
7. Earlier you made a note of the manufacturer from the supported devices list, so select that type now.
8. Select the model number of your router and the version number (from the under side of the router).
9. Select the File Version usually dd-wrt.v24_std_generic.bin.

Now, you can follow their instructions to do the installation.