Unbrick FRITZ!Box 7430

[Kamikater]

I might have bricked my FRITZ!Box 7430. It's an old device with only 100MBit LAN ports but it's sufficient to work as an access point in my case and I don't have to buy a new device.

I can't really remember what steps I did initially to brick it. I just followed the instructions but on the next step after reboot it was just gone.

I'll give it one more try. If it fails, the time I spend is not worth it and I rather use another device.

So, on powerup and constantly pinging I get a response for about 5 seconds from 192.168.1.1.

I get no response from

• 192.168.178.1
• 169.254.1.1
• 169.254.120.1

Immediately at the first ping response I hit

ftp 192.168.1.1

> ftp: connect: Connection refused

Then I cloned the OpenWrt git repository and ran

.\scripts\flashing\eva_ramboot.py 192.168.1.1 C:\Temp\openwrt-22.03.2-lantiq-xrx200-avm_fritz7430-initramfs-kernel.bin

ConnectionRefusedError: [WinError 10061] No connection could be made because the target machine actively refused it

I tried the recovery tool from AVM, but it couldn't find the device. I guess the IPs it's searching are hard-coded AVM FRITZ!Box 7430 recovery tool Great job AVM for removing the hardware reset button!

The device apparently has 2 bootable firmwares. I could switch to the other boot partition by executing

ftp> debug bin
ftp> quote GETENV linux_fs_start
ftp> quote SETENV linux_fs_start 0 (or 1)

Well, I can't connect to the tftp server

Is there anything left to try? Since there is something at 192.168.1.1 I guess OpenWrt might have been installed in some mysterious way.

This is a great tutorial btw: https://bitgrounds.tech/posts/getting-up-and-running-with-openwrt-on-fritzbox7430/

[slh]

In case of AVM, the bootloader really does use (only) ftp not the more commonly used tftp. The ftp implementation is a bit picky and doesn't like windows' onboard ftp console client too much, but as it's implemented in the OEM bootloader, it's always available and rather resilient.

As the exact time window to talk via ftp is rather short, you may have to try multiple (many) times and putting an unmanaged switch between the 7430 and your system running the ftp client is strongly recommended, to avoid interface deconfiguration and link training.

[psherman]

Cool... thanks for the info. I'll delete my prior post as not to cause confusion.

[Kamikater]

After spending a lot of time with tftpd32.exe and verifying that it actually works on my host, 7430 still didn't care, and I found the issue being on OSI Layer 8.

So when your host is at 192.168.1.30 with /24 with nothing but a switch between you and your router and you receive something via ping from 192.168.1.1 then you are in the correct network, right?

Wrong!

Why bother to check 192.168.178.1 when there is already an answer? After only switching to 192.168.178.1/24 with nothing else changed I got the same response at the exactly same timing from 192.168.178.1 It might still be that the router ponged on both IPs simultaniously, maybe?

Moving on, happy about a non-bricked router I instantly recovered the original firmware with the AVM tool. And then recovered again but this time using the tool for a wrong router (here 7590) so that the router get stuck in this state, giving me enough time to perform

.\scripts\flashing\eva_ramboot.py 192.168.178.1 C:\Temp\openwrt-22.03.2-lantiq-xrx200-avm_fritz7430-initramfs-kernel.bin

So the router was never bricked.

I will spare you from all the details and pitfalls I met until I got to this point.

Now, in order to perform a safe sysupgrade I have to run

# fritz_tffs_nand -d /dev/mtd1 -n linux_fs_start
ERROR: no value found for name linux_fs_start!

It should not output 1 before I continue. Since the value is not set it's either 0 or null, right?

The git commit says:

If linux_fs_start is 1, you will need to reset it to 0, either by FTP,
upgrading FritzOS or doing a recover

Now I'm not sure what to do. I want to try ftp 192.168.178.1 but if I reboot FRITZ!OS will boot and I have to start over again?

I found the package atftpd, a TFTP server. But it will not perform anything on the bootloader, right?

What should I do next? Any help will be appreciated.

EDIT:

I did it! I wasn't keen on it but I did all the steps again. I added just one more step with ftp 192.168.178.1, logged in, set linux_fs_start 0 and was dismissed with

221 Thank you for using the FTP service on ADAM2

You're welcome

Again, I highly recommend https://bitgrounds.tech/posts/getting-up-and-running-with-openwrt-on-fritzbox7430/. After everything I've been through, feel free to ask me anything if you are stuck with the same router.