All Cisco routers have a
16-bit software register thats written into NVRAM. By default,the configuration
register is set to load the Cisco IOS from flash memory and to look for and load the startup-config
file from NVRAM, and its vlue is 0x2102. You can change the configuration
register settings to provide password recovery on your routers.
If there are passwords configured on startup configuration
file, you should know the password to login into the router.If you don't know
the password you can reset the password without losing the previous
configuration.
For more details about boot sequence and configuration
register, read this article
Cisco boot sequence
Cisco boot sequence
So, you have to change the boot sequence (Configuration
register value) to skip the step of loading startup configuration file from
nvram to ram to login into the router without writing the passwords that you
don't know. After that, copy the startup configuration file into the ram and
change passwords.
Steps for resetting the passwords:
- 1. Change the value of configuration register to 0x2142 to skip the step of loading startup file into ram, when the router boots up, click CTRL+Break. After that you will login into rommmon mode to change the configuration register value and reboot the router.
rommon 1 >confreg 0x2142
You must reset or power cycle for new config to take
effect
rommon 2 >reset
- 2. copy the startup configuration file into the ram and change passwords.
Router#copy start run
Router(config)#enable secret xxxxx
- 3. set the configuration register back to the default value
Router(config)#config-register 0x2102
- 4. save the new configuration with a copy running-config startup-config and use reload to reload the router
Router#copy
run start
Router#reload
Note: It's important to
remember to enable your interfaces after copying the configuration
from NVRAM to RAM.
To watch
the video on youtube
To download the video from mediafire
https://www.facebook.com/groups/954180217947066/
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