Tomato is a partially free HyperWRT-based, Linux core firmware distribution for a range of Broadcom chipset based wireless routers. The original developer ceased development in 2010, but the community has continued his work. I use a version of tomato created by Michal Rupental aka Shibby. His version is one of the most robust and feature filled firmware for home routers. For a good overview of the features of different firmwares check out the wikipedia article on tomato.
Installing Tomato by Shibby on the ASUS RT-N66U is an easy and straightforward process once you know a few basics. There is so much information and different builds out there that it can be extremely overwhelming for a novice. About a year ago I wanted to upgrade my old WRT54GL running a 2010 build of tomato and bricked it by installing the wrong firmware. Hopefully this guide will help you avoid any possible misteps.
First you'll want to download install the ASUS RT-N66U Firmware Restoration utility from ASUS’ support site. I'm playing it safe and using the official Windows utility to do it. It is possible to do set everything up in Linux but I didn't want to risk another router. You'll want to enter RT-N66U as your model number. Download the most current version of the ASUS RT-N66U B1 Firmware Restoration utility.
Next you'll want to download the correct Tomato by Shibby build for your ASUS RT-N66U router. This guide is specially written for the ASUS RT-N66U Dual-Band Wireless-N900 Gigabit Router. If you have a different Asus router you'll want to look for a different guide no ensure compatibility.
Shibby's site has alot of different options on the Tomato Firmware Downloads page. You'll want to select the K26RT-N firmware builds. From here you'll want to select the newest EN build. Shibby's builds come in pl and en favors for Polish and English. Make sure you download the correct language. Then and then select the Asus RT-N66u 64k folder.
Quick breakdown of the download path:
tomato.grove.pl > download > K26RT-N/build5x-XXX-EN/ > Asus RT-N66u 64k
From here you'll have a couple different builds you can choose from. Here is Shibby's guide to what each contains. I prefer the AIO, all in one build, but you may want to find a firmware specific to your needs.
I used the AIO build:
Power off your ASUS RT-N66U and physically connect to it with a networking cable. Be sure to disconnect your PC from any wireless networks.
Open the ASUS Firmware Restoration utility and load Shibby’s RT-N66U firmware, but DO NOT start the restoration process First you'll need to place the router in emergency firmware restore mode.
Placing the router in firmware restoration mode can be a bit tricky. I found the best results to be unplugging the power supply from the router, making sure then power button is on the on position. Hold the reset button while plugging in the power supply. The power LED with begin to slowly blink, letting you know you are in emergency firmware restore mode.
Once the router blinks a couple of times, start the restoration process in the ASUS Firmware Restoration utility. Allow the process to run, disconnecting or turning off the router can lead to creating a pretty black paperweight. After a while the router will restart itself andthe wi-fi light will turn on. After the firmware uploads and installs you might get an error message saying the procedure failed, ignore it.
This is the step that through me off, you need to clear the router's NVRAM before it will work. Turn off the RT-N66U and while holding the WPS button turn on the router. Hold the button for 30-45 seconds and then release it.
After the router has rebooted, you can setup your router at http://192.168.1.1/. The default user name is root and the default password is admin.