I'm following the instructions at https://openwrt.org/toh/asus/rt-ac58u using the " Easy Installation" method - seemed faster than taking down my network while I disassemble the device and try to add a serial port to a computer that doesn't have one. 
Step 4 didn't quite work. The router didn't automatically reboot. I had to manually restart (as per the instructions on the screen when the flash finished), This booted me into OpenWRT from 5 or so years ago.
Step 5 fails. I get "unable to negotiate with 192.168.1.1 port 22: no matching host key type found. Their offer: ssh-rsa". I tried copying my id_rsa.pub key to the SSH-KEYS in the administration tab but that didn't help.
So I continued on to Step 6. However I can't flash any of the new firmware (nor revert to my old one). I get the message "The uploaded image file does not contain a supported format. Make sure that you choose the generic image format for your platform."
I note from https://lede-ac58u.zyxmon.org/HowToFlashENG.html that this is due to not being able to delete the files in step 4.
So I've got a working but old OpenWRT setup, I need to get ssh to work in order to update it. But ssh so far has not allowed me to connect from my Debian/Trixie workstation.
Any ideas?
ssh -o hostkeyalogorithms=+ssh-rsa
man 1 ssh for more infos
Thanks Brad4. When I corrected the typo and added the destination, it worked! e.g:
ssh -o hostkeyalgorithms=+ssh-rsa 192.168.1.1
However, even after deleting the files as per step 5 and even rebooting, I'm still getting the "The uploaded image file does not contain a supported format. Make sure that you choose the generic image format for your platform." message. I've checked the sha256 sum and it looks correct.
To make matters worse. I've discovered that in in addition to being old, the version of OpenWRT doesn't allow settings to be saved. It loses them every time it is rebooted.
I finally found the issue. The "easy" instructions miss an essential step - installing a second image from Zyxmon (a .tar file). Unfortunately, even with this second file installed, I'm still not able to flash a recent OpenWRT firmware file.
What is the exact dialog (make a capture of the dialog after uploading sysupgrade)
It's the same one that I reported - "The uploaded image file does not contain a supported format. Make sure that you choose the generic image format for your platform." I suspect the .bin format may have changed over the years. Perhaps the current format isn't compatible with the pre-pandemic .bin format.
Check the version of intermediate image, then crawl one version at a time
That was my thought. I went back to a pre-pandemic version and it seemed to work - it recognized it and went into the loading dialog then stayed there. I'm using a different router for now until I get the time to see if I can salvage it. Anyway, this confirms my suspicion that the format has changed...
1 Like