Dahua DHI-NVR4208-8P - how to downgrade firmware

n1x0n

n3wb
Nov 17, 2018
2
0
nyb city
Hi there,

I upgraded firmware on DHI-NVR4208-8P and IVS functionality is lost.

Old firmware: V3.201.0000.1.R.20160409
New firmware: V3.203.0000.0.R.20170612

When I try to downgrade - I instantly get "Update failed!" followed by a reboot.
I suspect it is checking for build date or version and doesn't allow downgrade - could someone confirm that this is the case ?

Are there any tested options to downgrade firmware ? I have rs232 working, and I see NVR tries to tftp - but it isn't clear if this is safe way to bypass - I would rather use a tested way.

Any hints appreciated !

Marek
 
Thanks - I can downgrade from V3.203 to V3.202 but not to V3.201 . Unpacking both V3.203 and V3.202 shows "sign.img" files, so I assume they started signing - hence I can't downgrade (3.201 has no sign.img")
 
Try downloading again maybe. Btw the bin file is actually a zip. If you change the extension to .zip you will be able ti verify integrity with WinRar or similar tools.
 
I think once you change to signed firmware you cannot revert to old unsigned firmware (which also has a LOT of security bugs, backdoors, etc). New does too but at least most are fixed. I think you might be able to manually do it using a serial cable though.
 
@TheDude
@riogrande75

I believe you guys are correct, you cannot return to older firmware through the convention route, like within the DVR application, but using tftp trick/serial connection it is possible.