Asus RT-AC66U, AdvancedTomato and flashing it on OSX

I just got a new router, the Asus RT-AC66U but I chose to install AdvancedTomato firmware on it.
I was searching for tutorials, everything I found described how to do it using the Asus Restore utility which is Windows only 😦
Also I was reluctant to setup a Windows VM just to only install Tomato. So instead I used the tftp tool which is included in OSX 🙂 .

  1. Download the AdvancedTomato firmware (in my case for RT-AC66U)
  2. Set a static IP on Ethernet on your OSX machine:,
  3. cd into the folder where you have downloaded the tomato firmware
  4. Restart the router in restore mode:
    1. Turn the router off
    2. While holding the reset button using a pen, turn on the router
    3. Keep holding the reset button for about 5 seconds until the power led starts flashing
  5. Connect a cable between the LAN port 1 (NOT the WAN port) on the router and your computer.
    • Verify that you can ping
  6. Upload the firmware using tftp in terminal:
    • tftp -e
    1. In the tftp shell execute these commands (enter the part after tftp> )
      • tftp> timeout 90
      • tftp> verbose
      • tftp> status
        • The output of the status command should be something like:
          • Connected to Mode: octet Verbose: on Tracing: off Rexmt-interval: 5 seconds, Max-timeout: 90 seconds
          • The main thing to watch out for in the output is that the mode is binary (octet) and that the timeout is high enough for the upload to complete.
  7. Still using the tftp shell, upload the trx file to the router:
      • tftp> put tomato-RT-AC66U_AT-RT-AC6x-2.5-124-AIO-64K.trx
      • The output should be:
        • putting tomato-RT-AC66U_AT-RT-AC6x-2.5-124-AIO-64K.trx to [octet]
      • The upload should finish in about 10 seconds:
        • Sent 16940400 bytes in 9.5 seconds [5041231 bits/sec]
  8. Wait for 5-10 minutes
    • After the upload is complete is that the router will restart and then install the firmware.
      • After the power light should stops flashing wait for 5-10 minutes, this is currently the only know indicator.
  9. NVRAM reset:
    • Turn off the router
    • While pressing the WPS button turn the router back on
    • Keep holding the WPS button for 30 seconds
    • After releasing the WPS button the router does a restart and the different lights flashes in the process, when the restart is complete all the lights should be on, including the WIFI lights (it took about 15 seconds on my router before all the lights were turned on)

Success, after the NVRAM reset you can ping

  1. Finally, go and configure AdvancedTomato –
    • Default user is root and password is admin
      • Change the password
    •  By default there is no security on WIFI
      • Enable security on the WIFI