FooCabFirmwareHowTo describes how we create firmware images for the AlixCab, WgtCab, and AcctonCab devices we've been working on. It should be suitable for following along at home. This is the document to read if you want to build your own node!

Historical Context


Bleeding Edge





Flashing method depends on the device. There are multiple ways of flashing most devices, some more relevant than others in various contexts. For example, WGT634U from a previous version of OpenWrt is going to probably have an easier method than if you start with Netgear stock firmware. More at OpenWrt's wiki: Installing OpenWrt (generic)

Updating r18781 FooCab firmware on WGT634U, Special Case

Modern WGT634U images can use the generic sysupgrade utility to flash a new TRX image. However, the state of sysupgrade on WgtCab of the previous generation was not fully functional (with regard to process shutting down, rootfs pivoting, etc). Also, the "mtd -r write <newimage.trx> linux" method is dangerous because some processes are still periodically looking on the flash for bits, and this will result in a kernel panic mid-flash (and a "brick") if you don't take precautions. Through trial and error, we have discovered the steps to flash an r18781 in a reasonably safe manner. Here are the steps:

Optionally, if you can connect directly to a public ipv4 address, you can shutdown the VPN. This doesn't seem to be necessary, and might be dangerous if you are not on-site. If there is no public interface that doesn't go through the VPN tunnel, DO NOT DO THIS. It's done simply in the interest of shutting down as many programs as possible.

Then, flash the new image using the mtd utility:

Watch the upgrade process. When the flash is complete, it will announce it is rebooting. Wait a few (3-5) minutes and try ssh'ing back into the device. Complete any necessary configuration tweaks, e.g. the SSID. It might also be necessary to restart SNMPD as it seems to start up before the VPN tunnel has been built on the first boot and so not all the interfaces will be reported.

If you mess up and the WGT panics or is otherwise interrupted during the flash, you will need a serial console to recover the device. RussellSenior has a pile of cell-phone data cables he got from China for $3/each that can be hacked for use as a USB-serial console cable. They took nearly 3 months to arrive, so don't try that at home if you are in a hurry. Contact Russell for help getting the serial console set up, or to have him flash your device for you.

FooCabFirmwareHowTo (last edited 2013-03-03 14:28:00 by RussellSenior)