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Home > Archive > CCNA > March 2001 > Config-Register
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| BigEasy 2001-03-23, 12:29 pm |
| I have a problem with a 2501 router. One of my students programed the router register to read 0x2e3a. I understand the default config is 0x2102, but can anyone give me any help with this problem or any links that may help in reseting the register. Thank you in advance | |
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| # conf t
(config)# config-register 0x2102
(config)# ^Z
# reload | |
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| Thanks but when the router boots all I can see on screen is encrypted letters. Ctrl-break did not work. | |
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| Maybe it did and you didn't notice because you get garbage on your screen. 0x2e3a means bit 8 is zero, which means break is not disabled. You may want to double check the settings in your HyperTerminal.
This makes me wonder: if you set bit 8 to zero, and sometime after that you need to do password recovery, how do you do it, since you cannot break?!
Anybody? | |
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| I am not sure about how to break out of a register that has bit 8 set high (or 1) but bit 11 tells the router to set below 9600.
Normal setting are 9600,8,N,1
I would try it again at 2400 baud, or lower.
Otherwise, the setup to recover the password (once it's ammends the proper baud rate) is as follows:
After break and you receive the following >
>o/r 0x2142
>i
this should start you back at the config mode.
ref to this is Que Exam Prep Kit, Aug2000 pg 446 showing registers 8 through 11, and bit 11 is a 1, bit 12 is a 0, tells the router to set baud rate below 9600.
Good luck... | |
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| quote:
This makes me wonder: if you set bit 8 to zero, and sometime after that you need to do password recovery, how do you do it, since you cannot break?!
Anybody?
I know for fact that I've read from Cisco's site that you can issue a ctrl+break regardless of the configuration register settings, if you issue it within a certain amount of time during boot. AFAIK, it had to be within 30 seconds, or somewhere in that time slot.
This makes me wonder what the intent of disabling the break would be. Anybody willing to try it on their router?  | |
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| Isn't it true that ctrl+break work with all os's (like nt, and w2k)? Just a thought. | |
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| quote:
Originally posted by firechicken
I know for fact that I've read from Cisco's site that you can issue a ctrl+break regardless of the configuration register settings, if you issue it within a certain amount of time during boot. AFAIK, it had to be within 30 seconds, or somewhere in that time slot.
This makes me wonder what the intent of disabling the break would be. Anybody willing to try it on their router?
Ctrl-break will always work during the first 30 seconds after a restart, regardless of config register setting. I'm not sure if it has to be a power-on restart, or whether a reload command will suffice.
I've never been able to think of a case when ctrl-break being disabled would help you. Security would be the only possible use I can imagine, and it seems useless as a security feature. If someone has physical access to your router, they can defeat the setting with the power button and do password recovery. So it won't help. If they don't have physical access, but have console access over a modem or something, they can't reload the router without the enable password. If they have the enable password, they don't need to do password recovery, and can change whatever they like in the router, including changing the config register to allow Ctrl-break.
So if the bad guys have physical access, you're dead no matter what. If they have dial-in console access but no enable password, they can't reboot the router to do password recovery. You're OK no matter what (except that someone is peeking at your router and you don't seem to know it). If they have remote console access and the enable password, you're dead no matter what; they have everything they could want without reloading the router at all.
I don't see the point either. It's probably something Cisco put in there because other equipment has that kind of option.
Mindless meanderings as a long night at work creeps to its close,
doctorcisco | |
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| Thanks for your help. I will try to lower buad rate and see what happens. As far as control break goes even if the command worked I can not read what in on the screen. The screen puts out nothing but encryption. I actually let it "boot" for 30 minutes and after the process stopped nothing would happen. I could type in through keyboard however it just displays more encryption. | |
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| Here is a ctrl-break list.
http://www.cisco.com/warp/public/701/61.html
or
you can try this, let the router boot and at the prompt enter:
bit #
this may bring up the full ios and then you can do config-register 0x2102 & copy run start.
hope this helps. | |
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| Thank you all for your input. Dropping the baud rate to 2400 actually allowed me to be able to read the boot in "regular" script. From there I proceeded to change router back to the 0x2102 config. |
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