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Recovering Cisco Router Through ROMON
Created On:14 September 2022
Written by:Ben
Overview
If you find yourself locked out of your Cisco router worry not! This article should provide you with details regarding the recovery process on Cisco routers and the different recover methods that can be used to regain access.
Some of the methods discussed here will wipe your configuration on the router. Please be careful and approach the details of this article with caution.
Recovery Process
Important notes:
If you cannot access romon mode after spamming the ESC key or issuing the BREAK command from your preferred serial client the likelihood is that password recovery is disabled on the router. In order to get around this you will need to try holding the reset button on the back of the router for 15 seconds after you have powered it on. You should be greeted with a login prompt, enter username cisco password cisco to gain access. If this does not work read through the advanced recovery section of this article.
If using the reset button on the back of the router does not allow a full wipe and you are stuck with the existing config after attempting the only way to recover would be using ROMON prompt.
While connected to the router via Serial cable attempt to issue the BREAK KEY command on boot. If using PuTTy this can be done by using Special Commands inside of the right click menu:
You should see this prompt:
rommon 1>
Change the configure register value to ignore the startup configuration by issuing the confreg command, as shown in this example:
rommon 2> confreg 0x2142
To reload the router, issue the reset command, as shown in this example:
rommon 3> reset
After the router boots, issue the enable command at the Router > prompt. The prompt changes to Router#, indicating that the router is now in privileged mode.
To enter config mode, issue the config terminal command. You should now see a Router(config)# prompt.
To change the configure register to recognize the startup configuration, issue the config-register command, as shown in this example:
Router (config)# config-register 0x2102
To break out of configuration mode, press Cntl and Z.
To save the blank configuration, issue the copy running-config startup-config command.
