Zyxel NBG6817 U-boot Recovery

Ortiz · June 2023

I have a couple of APs that were flushed with a custom openwrt build for FB-Soma-mesh Project that I would like to recover and flash with a newer openwrt/zyxel firmware... I currently do not have root password but I do have serial access... The failsafe mode has been disable and also tftp boot prompt by pressing the wps button on power on... Attached is the output from serial port for both 'printenv' in u-boot,..... Is it possible to update the U-boot and flash a a new firmware?

4.txt

3.txt

tonygibbs16 · June 2023

Hello @Ortiz

Welcome to the forum.

The instructions at https://openwrt.org/docs/guide-user/troubleshooting/root_password_reset might help you.

There is also a dedicated Openwrt page for NBG6817 at https://openwrt.org/toh/zyxel/nbg6817

Kind regards,

Tony

Ortiz · June 2023

Hi Tony,

Thanks for the share, My issue is that there is no failsafe mode, seems like it was disabled on that bild as per the serial output I shared.... I only access u-boot menu during boot

tonygibbs16 · June 2023

Hi @Ortiz

You're welcome.

There is mention of Poky in your logs, which is the Yocto Project Reference Distribution, and it suggests that it is version 2.7 (warrior), which has some documentation at https://docs.yoctoproject.org/2.7/mega-manual/mega-manual.html

But I haven't found much more yet.

Kind regards,

Tony

Ortiz · June 2023

3 hrs into the document, nothing useful of getting failsafe or recovery active... Any ideas of how to upgrade the bootloader

tonygibbs16 · June 2023

Hello @Ortiz

This looks like a way of upgrading U-boot but not the Poky.

https://u-boot.readthedocs.io/en/latest/usage/dfu.html

And this might also help https://gist.github.com/yoyosan/af11ad438b2a5b0ed9914cfa9bad3219

if you can get the Zyxel firmware.

This link seems to have some old Zyxel firmware from 2017 https://drivers.softpedia.com/get/Router-Switch-Access-Point/Zyxel/ZyXEL-ARMOR-Z2-NBG6817-Router-Firmware-1-00-ABCS-3-C0.shtml

Although this is not the latest Zyxel firmware according to

https://community.zyxel.com/en/discussion/12783/zyxel-security-advisory-for-command-injection-and-csrf-vulnerabilities-of-select-armor-home-routers

Once you have installed that Zyxel firmware successfully then you could try to install the latest release of Openwrt. See https://openwrt.org/docs/guide-user/installation/generic.flashing using the firmware update option of the Zyxel firmware.

Kind regards Tony

Ortiz · June 2023

Hi,

Seems like the OS was based of the Lede version, I was able to flash lede v 17.0.1....but now I can't move to openwrt newer versions... I have to move to 18, but seems like something is a miss... Keeps rebooting during kernel initialization

Ortiz · June 2023

Hi,

Also I was able able to compile/download a working updated u-boot... Might it be that the u-boot is of an older v?

tonygibbs16 · June 2023

Hi @Ortiz

Maybe…It is dated 2017 in your logs. But it might still work enough to allow you to load Zyxel firmware.

This might help too, see https://forum.openwrt.org/t/solved-zyxel-nbg6817-flashing-from-oem/768 and https://openwrt.org/docs/techref/bootloader/uboot

Kind regards,

Tony

Zyxel NBG6817 U-boot Recovery

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