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Question about ROMMON mode

I have a Cisco 806 with the CBAC firewall package on it. This morning when I went to use my pc I noticed i had no conneciton, I went to check the router and I dont know why it was in rommon mode. I reset the router and it came up fine and I had connection again. This strikes me as weird it had never happened before. I thought maybe a power outage might have caused it but usually when that happens the router just reboots and goes into regular mode. My coworker thinks I might have been hacked. The router is connected to a pc with server software which is always on, and a desktop which i turn off when im not home. Another weird thing is the server was at the logon prompt and asking my why the pc had been turned off unexpectedly. This usualy will show when a power outage occurs....if someone had rebooted it (eg. hacked in ) it shouldnt have asked that cos it would have been an expected shutdown.

My question is, any ideas on why the router would have gone into rommon mode like that? there's no one at home so there's no way someone could have physically done somehting in the equipment.

Thanx for any input!


Cisco Employee

Re: Question about ROMMON mode

Make sure that your config-reg is set to 0x2102

"806#sh ver

Cisco Internetwork Operating System Software

IOS (tm) C806 Software (C806-K9OSY6-M), Version 12.3(1a), RELEASE SOFTWARE (fc1)

Copyright (c) 1986-2003 by cisco Systems, Inc.

Compiled Sat 07-Jun-03 05:03 by dchih

Image text-base: 0x80013170, data-base: 0x80ACFB40

ROM: System Bootstrap, Version 12.2(4r)XM1, RELEASE SOFTWARE (fc1)

806 uptime is 6 weeks, 23 hours, 1 minute

System returned to ROM by reload

System image file is "flash:c806-k9osy6-mz.123-1a"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

If you require further assistance please contact us by sending email to

CISCO C806 (MPC855T) processor (revision 0x401) with 30720K/2048K bytes of memory.

Processor board ID VMS061407NK (3989362470), with hardware revision 0000

CPU rev number 5

Bridging software.

2 Ethernet/IEEE 802.3 interface(s)

128K bytes of non-volatile configuration memory.

8192K bytes of processor board System flash (Read/Write)

2048K bytes of processor board Web flash (Read/Write)


Configuration register is 0x2102 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<

New Member

Re: Question about ROMMON mode

I think your are having the power outage in your house. From my experience, when you boot up pc and the router together with the console cable connected; sometime the router will go to the Rommon mode. Router sometime will detect the signal coming from PC similar to Ctl-Break.

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