Re-flashing a WRT54GL running HSMM Ham Mesh firmware

I recently flashed the firmware on a spare Linksys WRT54GL to take a look at ham radio mesh networking on 2.4GHz re-using WiFi routers like the WRT54. I wanted to flash the router back to regular WiFi router firmware, and turned out this was more difficult than it should have been. For future reference, here’s a few notes.

The HSMM-Mesh firmware (3.0) has an admin page to either upload a new firmware to flash, or download an existing firmware from a list of available firmware versions. Neither of these worked for me – uploading a firmware gave an error that it wasn’t recognized, and then the router was connected to my network for internet access, it didn’t give any firmware options other than later versions of the HSMM firmware.

Elsewhere there are instructions for using the tftp approach to ftp a new firmware to the router as it boots. This seemed like an easy option, but I could not get it to work despite trying multiple times.

Instructions for OpenWrt here give steps for ensuring the tftp feature is enabled… this apparently is key, as before following the steps I could not get it to work, but after setting this options it worked first time.

ssh to the router using:

ssh root@10.72.105.9 -p 2222

this is the ip that my HSMM had on starting up, and sshd on the HSMM firmware is enabled by default and listening on 2222.

From thr OpenWrt page above, enter these commands to setup tftp:

nvram set boot_wait=on
nvram set boot_time=10
nvram set wait_time=10 #important for some models
nvram commit && reboot

Before the reboot step, set your ip address on laptop connected to router as:

192.168.1.2
netmask 255.255.255.0
router/gateway 192.168.1.1
Reboot router, start following the tftp procedure to upload the firmware:

If you are seeing WRQ messages with tftp trace turned on, the router is responding, but not yet accepting the tftp upload. You need to wait until you see messages like this to indicate the transfer is occurring:

sent DATA <block=6562, 512 bytes>
received ACK <block=6562>

These will repeat several times a second until the upload is complete, then they will stop, tftp will disconnect, and you’ll see the router power light flashing, indicating it is rebooting. Wait a couple of minutes until the lights are back to their normal state, and then try hitting the admin page for the new flashed firmware at 192.168.1.1

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