Password recovery - confreg 0x2142 doesn't work

Answered Question
Mar 21st, 2007

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

I have this problem too.
0 votes
Correct Answer by sundar.palaniappan about 7 years 1 month ago

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;

---------------------------------------------------------------------------------------

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.

---------------------------------------------------------------------------------------

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

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Correct Answer
sundar.palaniappan Wed, 03/21/2007 - 11:27

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;

---------------------------------------------------------------------------------------

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.

---------------------------------------------------------------------------------------

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 Thu, 03/22/2007 - 00:59

Hi Sundar,

Thanks for the procedure. It works perfectly !

Best regards;

Yann.

mioconnor Wed, 08/22/2007 - 18:39

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

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Posted March 21, 2007 at 11:06 AM
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