Cisco password recovery

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Cisco 1841

This is compressed process of Password Recovery Procedure for the Cisco 1700 and 1800 Series Routers for Cisco 1841 router.

  1. Console to the router with Tetra Term and send Break (alt+b) at POST. Literally power off/on and send break straight after 2 seconds or when you see the first lines of booting messages.
    rommon 1 > confreg 0x2142 
    You must reset or power cycle for new config to take effect 
    rommon 2 > reset
  2. Answer No or press ctrl+c to skip auto configuration
  3. Type enable>
  4. Type configure memory or copy startup-config running-config in order to copy the nonvolatile RAM (NVRAM) into memory.
  5. Type configure terminal
  6. Type enable secret <password> in order to change the enable secret password
  7. Issue the no shutdown command on every interface that you use.
  8. Type config-register <configuration_register_setting>. Where configuration_register_setting is either the value you recorded or 0x2102
    hostname(config)#config-register 0x2102
  9. Type end and write memory or copy running-config startup-config to save changes
  10. Type reload

Configuration register

The configuration register tells the router how to boot. There are many possible settings for the configuration register. The most common ones are:

  • 0x2102 - Factory default setting for Cisco routers (load the IOS image from flash and load the startup config file from NVRAM)
  • 0x2142 - Router ignores the contents of Non-Volatile RAM (NVRAM)
  • 0x2120 - Router boots into ROMmon mode