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Author Topic: Sanity-check question - ZyXEL modems - firmware upgrade  (Read 468 times)

Weaver

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Sanity-check question - ZyXEL modems - firmware upgrade
« on: March 27, 2020, 09:49:53 PM »

Daft question: if you load a new firmware file into the flash on a ZyXEL modem, when it boots up Iím assuming it will be using the same config as before, is that correct? Or does it wipe out the config and go back to either the ROM-D or the factory default config? Just checking.

Iíve got a lot of modems to do firmware upgrades on and Iím wondering about the quickest way of doing it. If the config is reset, mine will change admin i/f IP address, because they are not in general using the standard 192.168.1.1. That will mean I will have to do more steps to upgrade them so as to cope with the loss of connection when the IP address changes if they remain in situ.
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burakkucat

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Re: Sanity-check question - ZyXEL modems - firmware upgrade
« Reply #1 on: March 27, 2020, 10:07:29 PM »

You are referring to ZyXEL VMG1312-B10A devices, of course. When the firmware is updated, the user configuration is preserved.

On receipt of a new device (factory new or new to me), I would always --
  • Perform a press and long hold of the reset button.
  • Clear the ROM-D, to remove any ISP customisation.
  • Update the firmware.
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Weaver

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Re: Sanity-check question - ZyXEL modems - firmware upgrade
« Reply #2 on: March 28, 2020, 01:39:13 PM »

I clear ROM-D as the last step after I have flashed firmware and have then loaded a standard config file. I have recorded a particular supervisor password in my notes and this password is also in a Ďmacroí in a list of snippets of named, stored text within my telnet app, Prompt2. This password must be in my XML config file. What do users do who donít know their supervisor password? Answer: ask burakkucat, thatís what.  ;)  I donít know where I originally got my password from ?

Can an admin simply set the supervisor password? Maybe thatís what I originally did.
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burakkucat

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Re: Sanity-check question - ZyXEL modems - firmware upgrade
« Reply #3 on: March 28, 2020, 04:20:28 PM »

What do users do who donít know their supervisor password? Answer: ask burakkucat, thatís what.  ;) 

Thank you for the accolade.  :blush:

Quote
I donít know where I originally got my password from ?

I can't remember the details . . . possibly parsing the output of the dumpmdm command?

Can an admin simply set the supervisor password? Maybe thatís what I originally did.

No. One needs to be operating with supervisor privileges to change the password.
« Last Edit: March 28, 2020, 04:23:48 PM by burakkucat »
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Re: Sanity-check question - ZyXEL modems - firmware upgrade
« Reply #4 on: March 28, 2020, 08:07:06 PM »

I must have got a certain kuro neko to help as I would never have been able to do it on my own without some help. Is there a known factory default supervisor password ? If so, perhaps I logged in with knowledge of that and still in that virgin state and then set the supervisor password to some non-default value?

I wonder if my supervisor password is the same as yours ?
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burakkucat

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Re: Sanity-check question - ZyXEL modems - firmware upgrade
« Reply #5 on: March 28, 2020, 09:22:46 PM »

The original (that is, historic) supervisor password for ZyXEL VMGnnnn CPEs was zyad1234 . . . but I have never come across a device which recognises that string.

All devices now have individual eight digit hexadecimal numbers for their supervisor passwords.
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Re: Sanity-check question - ZyXEL modems - firmware upgrade
« Reply #6 on: March 29, 2020, 12:30:08 AM »

Burakkucat said to me in a PM that he was doubtful that all my modems have the same supervisor password.

The answer is that they most certainly do share one single supervisor password. I know because I have it set the password as a saved text-snippet/macro in my telnet client app (iOS Prompt2 app) so I can just inject the password into the telnet session with two clicks and I use that when logging in with telnet. I have one macro for the admin password and one for the supervisor password - I suppose I could have made them the same now I come to think of it.

Is the syntax of a supervisor password limited? I presume not, not the test would be if you attempt to set it to something random and strong yourself.

I just donít understand those passwords. They could come from some random number generator that returns a 32-bit iirc integer and converts that to ascii hex. They could mix in the MAC address of the device as the random number generator might need more sources of variability, or also mix in the current time, hi-res if possible. If they did any of those or similar things then the default passwords would never be the same across my modems. However that presumably is irrelevant as Iím not looking at virgin state / post factory reset state modems, Iím looking at the state after loading up my standard saved config and I just presume that supervisor is one of the account name-password entries stored in the xml config, just no different to "admin".
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burakkucat

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Re: Sanity-check question - ZyXEL modems - firmware upgrade
« Reply #7 on: March 29, 2020, 05:31:53 PM »

One, much wiser than I in such matters, suggested that the base supervisor password might be the output of a function that operates on the full 13-character serial number of the ZyXEL device.

supervisor_password = f(serial_number)

Suggestions as to f() have been variations on the CRC32 and Adler32 transformations.
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Re: Sanity-check question - ZyXEL modems - firmware upgrade
« Reply #8 on: March 29, 2020, 06:00:47 PM »

And that would be the factory default one then? So I then took one such, saved it in a saved config file, and now I overwrite all such passwords with a single weaver-std password loaded up from my config files?
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burakkucat

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Re: Sanity-check question - ZyXEL modems - firmware upgrade
« Reply #9 on: March 29, 2020, 07:14:22 PM »

Possibly, yes.
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