Netgear WNR834Bv1

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[edit] Introduction

This model (the V1) does NOT have a JTAG header, only serial, so caution must be exercised when working on this unit.

Not much is said about this device other than flash it with a modified header. All information I found was that there was not modified header build for this unit except that which was created by SveaSoft with their Talisman 1.3.1 package.

[edit] Notes on Flashing

So... after much investigation it was found that the firmware needs to be updated in the form of an .img file. Original Netgear firmware was a .img file and would only accept TFTP input or web GUI input of a .img file.

[NOTE] - further investigation proved that the .img file is actually a .zip file. You can rename the .img to .zip and extract the contained WNR834B.bin file. Using a hex editor this .bin file contains both the CFE and FW for the by removing the first byte through the last byte before the HDR0 in the file will leave just the FW of the .bin file... this is a .bin file and CAN be flashed directly to the unit using TFTP.

Also found was that any .bin file can be flashed using TFTP to the unit unless the nvram has been erased using the CFE's "nvram erase" command then it will need flashing with the original .img file again. Once the Netgear FW .img is flashed navigate to the upgrade FW tab and use the 11580_mini build of .img provided below.

I found that Simri created a .img build for this unit and it works very well. The first loading of DD-WRT firmware must be an .img file and can be loaded from the Netgear firmware update tab.

11580_mini build of .img

Hard reset
Load firmware ( with admin/password for un/pw)
wait 5 minutes
power cycle router
hard reset again

Subsequent DD-WRT firmware updates can be done from the DD-WRT firmware update page and you can load any .bin file except for the mega build. (I suggest you don't downgrade lower than the 11580 build that you used for the initial flash)

Here is the original Netgear firmware as well for those that want to revert back.

Additional information about this unit can be found here


[NOTE] - if you have DD-WRT on the unit and have the wrong MAC address. You can use another method of obtaining the correct MAC address permanently.

Extract the cfe.bin by using the HTTP backup method (save this file to your disk drive) Edit the cfe.bin file using a hex editor...locate and modify both the et0macaddr and et1macaddr to be the MAC address with that which is found on the sticker of your unit (yes...both et0 and et1 will be that address)....Make sure you do not ADD any bytes to the file (only overwrite current bytes)....if you do add to the will have an unrecoverable brick....guaranteed...remember you only have serial communication and the CFE must work for serial to work.

Then using WinSCP (SSH must be enabled in DD-WRT) copy the newly edited CFE to the unit's /tmp directory. Now you can use a telnet session to mtd the new CFE over the old must have the exact same CFE with only the MAC address's changed for this to work...if you don't you will have an unrecoverable brick...guaranteed.

the commands for overwriting the CFE is

mtd unlock cfe
mtd write /tmp/cfe.bin cfe

When it finishes reboot the router. The correct MAC addresses should now show up on the Status tab.

Thanks to Sparky and Simri for sharing their knowledge of these Netgear units on the forum. redhawk