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    Clear a Cisco 1605 router password

    I recently had need to wipe the passwords on a Cisco 1605 router and thought I’d document the process here. It’s really pretty easy…

    1. Hook the router up via the serial console to ttyS0 of some Linux box.
    2. Fire up minicom and connect to /dev/ttyS0 at 9600 bps, 8 data bits, no parity, 1 stop bit.
    3. Power cycle the router.
    4. Within 60 seconds of powering it up, send a BREAK signal to it.
    5. The router will drop you into the rom monitor with a “rommon 1 > ” prompt.
    6. Type ‘confreg’ to enter the configuration register utility. You will be asked a series of questions. Answer no to all questions except;
      do you wish to change the configuration? y/n [n]: y
      enable “ignore system config info”? y/n [n]: y
      change the boot characteristics? y/n [n]: y
      enter to boot: 2
      do you wish to change the configuration? y/n [n]: n
    7. Power cycle the router.
    8. Would you like to enter the initial configuration dialog? [yes/no]: no
    9. At the “Router>” prompt, type `enable` to enter privileged mode.
    10. Type `configure memory` to copy the configuration file from NVRAM into RAM.
    11. Type `configure terminal` command to enter configuration mode.
    12. Type`no enable password` and `no enable secret` to clear both of those passwords.
    13. Type `line 0` (thats a zero) then `no password` to clear the console port password.
    14. Press <control-z> to exit configuration mode.
    15. Type `copy running-config startup-config`.
    16. Destination filename [startup-config]? startup-config
    17. Power cycle the router.
    18. Would you like to enter the initial configuration dialog? [yes/no]: no
    19. Type `enable`.
    20. Type `configure terminal`.
    21. Type `config-register 0×2102`.
    22. Press <control-z>.
    23. Type `write`.
    24. Power cycle the router.

    That should be it. Your router is back to a default state. You can now restore its config from a backup or do whatever else you like.

    This entry was posted on Sunday, March 2nd, 2008 at 4:26 pm and is filed under HowTo, IOS. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

    One Response to “Clear a Cisco 1605 router password”

    1. mike says:
      2008/03/09 at 5:32 pm

      It may be better to communicate that while this is the process for the 1600 series routers, changing the configuration register thru the process described is not valid for all router types. The definitive method for discovering the best process for this is to use the Cisco Password Recovery Procedures. A Google search for that exact term will lead you where you need to go or use the following URL: http://www.cisco.com/warp/public/474/index.shtml

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