There might be tons of same topic on Inter-Web, especially on Cisco website, but I still decide to post it, at least I can archive in case I lost computer or notebook…
Cisco Router/Switch Password Recovery:
1. Apply break during the device booting sequence: Mostly the “Ctrl + Break” will work. I use putty 99% of time and putty needs to be configure/accessed via clicking the left mouse button on the icon in the top left corner of PuTTY’s terminal window to see the special command “break”.
2. Set configure register: rommon 1> confreg 0x2142
3. Reset the device: rommon 2> reset
4. Type no after each setup question, or press Ctrl-C in order to skip the initial setup procedure.
5. Type configure memory OR copy start run
6. Change password(s) when device boots up completely
7. Restore the config register: hostname(config)#config-register 0x2102 <– REMEMBER TO DO IT
8. Type write memory or copy running-config startup-config in order to commit the changes.
9. Reload device.
NOTE, all interfaces are shutdown when doing password recovery. So manual “no shut” is needed for each interface.
For recovering password for Cisco ASA, check here.
See Also: Cisco Reference