doesnt need one its all set up ready to roll once you plug in you might have to hard rest which is on the back a small button then it will be set up with default dd-wrt firm ware when you login into router settings
I work in IT. DD-WRT is a firmware that boost performance of many routers. There are guides available online if you want to go back to the Linksys firmware. This router works for DSL/Cable/LAN/SAN/WAN.