Password recovery - confreg 0x2142 doesn't work

[augure81yl]

Hi,

On a Cisco 7600 with SUP720-3BXL the password recovery procedure doesn't work.

In rommon I try to use the configuration Register to boot without password and without configuration load but nothing... The router still ask me login/password for console access.

The procedure was :

boot in rommon -> confreg 0x2142 -> reset (or power off/on) -> IOS boot -> login/password....

I test several values but nothing...

Do you know another method to retrieve a valid access ?

Regards

[sundar.palaniappan · Accepted solution]

Here's one reason why the router mayn't be ignoring the config;

The router reboots. However, it ignores its saved configuration due to the fact that the configuration register is set to 0x2142. If you see that the router configuration is still present (still previous hostname), it indicates that the configuration register was not changed to 0x2142 in time prior to the crash. If this is the case, start over again (Step 4). If the configuration register is correctly changed to 0x2142, you get the initial configuration questions after the reload.

Steps 4 - 6 are as follows;

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4 Power down and then power up the router with the help of the power switch.

5 Press Break on the terminal keyboard right after the RP gains control of the console port. On the Catalyst 6500 that runs Cisco IOS, the SP boots first. It then turns control over to the RP. After the RP gains control, initiate the break sequence. The RP has gained control of the console port when you see this message. (Do not initiate the break sequence until you see this message):

00:00:03: %OIR-6-CONSOLE: Changing console ownership to route processor

Due to Cisco bug ID CSCec36997 ( registered customers only) (Password recovery on sup720-native leads to crash on SP), you have about 10 seconds to complete Step 6 before the switch crashes.

If the break sequence does not work, refer to the Standard Break Key Sequence Combinations During Password Recovery for other key combinations.

6 Type confreg 0x2142 at the rommon 1> prompt to boot from Flash without loading the configuration.

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Do you see the configured hostname or Router prompt after it comes back up?

Also, pay attention to the part where it says to break in when SP transfers control over to the RP and the 10 seconds you have to change the config register.

HTH

Sundar

[augure81yl]

Hi Sundar,

Thanks for the procedure. It works perfectly !

Best regards;

Yann.

[mioconnor]

I have tried exactly this routing and can never get my break sequence to work to get into ROMMON of the RP. Hence I can never do the confreg 0x2142 and reset commands. So, the config is still in tact and I can never do a pwd recovery. I have tried WinXP Hypterminal Ctrl-Break or Break, tried TeraTerm which is Alt-b, and Procomm Plus and nothing. Please help. Thank you, Mike

[shahulreg]

Hi,,

There is a separate document in Cisco for resetting confreg.

Pls find the below :-

http://www.cisco.com/c/en/us/support/docs/routers/10000-series-routers/50421-config-register-use.html#purpose-config-register

Hope this might help u

[sameulChoudhury52443]

hi ive followed these steps, there is no inclination in regards to this message "00:00:03: %OIR-6-CONSOLE: Changing console ownership to route processor"

it either loads as normal or it goes into rommon, as I put in the command confreg 0x2142 and reset it goes back into the initial configuration. I am unsure about the logins for this device, however if I het enter enough times I get into console (enable): allowing me to set commands but again once reset it reverts back to the original configuration.

[dinesh_mih]

Thanku so much. This has resolved the issue for me!!!!

[ISMAILACOLLEY0514]

hey, i have a cisco ISR Router 871, i am trying to recover the password by  rommon1 but i usually have  an erron on the command confreg 0x2142, any idea why?

[m.sameeer1]

hi, engineers, 

I have a problem with router cisco 1841 

[Telsource NMC]

i just ran into this very same issue with a Cat 4500X.  the command confreg 0x2142 would out put with "usage: confreg" while in rommon.  it would never actually change the reg set up.  i ended up having to find another cisco page that showed what each reg code actually means  (and ill provide a link to the site i went to) in order to get it to change to, what i ended up needing to use 0x2141.  in the section below i ended up having to make a few changes to make it happen.  and ill show the changes i made to make it the 2142 or 2141

rommon 2 >confreg

Configuration Summary :
=> ignore system config info
=> console baud: 9600
=> autoboot from: commands specified in 'BOOT' environment variable

do you wish to change the configuration? y/n [n]: y
enable "diagnostic mode"? y/n [n]:
enable "use net in IP bcast address"? y/n [n]:
enable "load rom after netboot fails"? y/n [n]:Y
enable "use all zero broadcast"? y/n [n]:
enable "break/abort has effect"? y/n [n]:Y
disable "ignore system config info"? y/n [n]:Y

change console baud rate? y/n [n]:

change the boot characteristics? y/n [n]: y

enter to boot:
0 = disable autoboot
1 = the first file from internal flash device
2 = commands specified in 'BOOT' environment variable
[2]:(when i changed this to (2) the reg at reset was 0x2 not sure why but should have actually been 0x2142, but changing it to 1 did make the reg 0x2141 with the above bold changes.

this is the config summary I ended up having to use to make it work

Configuration Summary :
=> load rom after netboot fails
=> ignore system config info
=> console baud: 9600
=> autoboot from: the first file from internal flash device

here is the cisco link that helped me figure out what parts i needed to activate and deactivate to make the reg i did.

https://www.cisco.com/c/en/us/support/docs/routers/10000-series-routers/50421-config-register-use.html

i hope this helps other that encounter my issue in the future.

Joseph Blosser