Friday, 15 April 2016

Breaking (resetting) into a Cisco IOS Router from the console

If in the event you have purchased a second hand Cisco router or switch and the seller has happened to leave the existing configuration on it (with a password mind!) or worse yet you have forgotten your login details! - We can reset the device from the console.

Connect to the device's console and as soon as the device starts booting - issue the 'Break' key (this is can be done with 'Alt + B' in HyperTerm or in Putty you can right hand click the title bar >> Special Commands >> and select 'Break'.

This will get you into RomMon mode - here we should issue the following to erase the startup configuration:

confreg 0x2142

Then reload the router as normal and once booted in we should then run the following to ensure that our new configuration is not erased upon the next reboot:

config-register 0x2102

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