Kostis Netzwerkberatung
Konstantinos Kostis
Talstr. 25, D-63322 Rödermark
Tel. +49 6074 881056, FAX 881058
kosta@kostis.net, http://www.kostis.net/

You may use this information free of charge at your own risk

V1.02 2002-06-01

mini-Howto: Recover a Cisco Router

Unknown Cisco password and no documentation?

I've seen this numerous times. Customers tell you they have a spare Cisco router and ask you to configure it. "Sure, no problem", you say and think but then their router comes without a console cable, nobody knows any passwords and/or who may have configured it, so that leaves you with only one option: recover.

Recover a Cisco Router

To recover a Cisco router, connect a terminal or PC with terminal emulation serial port such as COM1: to Cisco console (RJ-45) port. Communication parameters are 9600-8-n-1-none.

Right after you turn on your router power send Break (real DEC VT terminal emulations have F5 for that).

Depending on the Cisco model a simple prompt shows up.

Cisco 160x Series

User break detected at location 0x2006718
rommon 1 > confreg 0x2142
rommon 2 > i

Cisco 250x Series

Abort at 0x3171892 (PC)
>o/r 0x2142

This will tell your Cisco to ignore its startup-config file from now on and then reboots.

After reboot, now without any configuration, type:

> enable   enable mode
# erase startup-config   erase old configuration including passwords
# configure terminal   prepare changes for register value
# config-register 0x2102   recover original register value
# exit   return to command mode
# reload   do not save changes if any

Yes, it is that easy. ;)