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Thread: Resetting a Cisco Router

  1. #1
    Senior Member SephStorm's Avatar
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    Default Resetting a Cisco Router

    I know this is going to seem suspicious, but I can assure you, the router is my property. If whoever can assist doesn't feel comfortable sharing on the open forum, feel free to PM me your reply.

    How can I reset a Cisco router to factory defaults without the password? I just purchased a used router off ebay, and of course the thing was pw protected for enable mode. According to the cisco website, I need access to enable mode to reset the router.

    Or, if someone has any idea who I could obtain the pw, that would be acceptable.

    EDIT: Disregard, a little more research proved the answer.
    "You're only smoke and mirrors..."

  2. #2
    Senior Member secure_it's Avatar
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    ROMMON mode.change the confreg value to bypass NVRAM contain & once done reset to default.

  3. #3
    Good friend of the forums
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    just some extra

    Power cycle the router.

    2. Press the Break key (for Windows 2000, press Control-Break) to enter into boot ROM mode. The Control-Break key sequence must be entered within 60 seconds of the router restarting after a power cycle. Other terminal applications will have their own sequence, so make sure that you consult the help files.

    3. After you are in ROM mode, change the configuration register value to ignore the startup configuration file that is stored in NVRAM. Use the o/r 0x2142 command (2500 series routers). For Cisco IOS 12.2T (2600 models and higher) or later the command is confreg 0x2142.

    4. Allow the router to reboot by entering the i command.

    5. After the router has finished booting up (you will be prompted to enter the setup dialoganswer no or press Control-c to abort the setup dialog) without its startup configuration, look at the show startup-config command output. If the password is encrypted, move to Step 6, which requires you to enter enabled mode (type enable and you will not be required to enter any password) and copy the startup configuration to the running configuration with the copy startup-config running-config command. Then, change the password. If the password is not encrypted and the enable secret command is not used, simply document the plain-text password and go to Step 8.


    6. Because the router currently has no configuration in RAM, you can enter enabled mode by simply typing enable (no password is required). Copy the startup configuration to RAM with the IOS command copy startup-config running-config.

    7. Enable all active interfaces.

    8. Change the configuration register to 0x2102 (default) with the global IOS command config-register 0x2102. Note that this IOS command is automatically saved and there is no need to write changes to NVRAM when modifying the configuration register even though the IOS image will prompt you to save when you do perform a reload.

    9. After saving the configuration, you can optionally reload the router.

    10. Check the new password if it is not encrypted. If the password is encrypted, simply enter enabled mode and verify your password.


    These are the generic steps for password

  4. #4
    Very good friend of the forum Gitsnik's Avatar
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    Default

    Actually the sanest thing anyone can do is google their model, albeit compaq's method will work on quite a few devices - Cisco provide extensive documentation on exactly this (as Seph obviously discovered), and they are not standard across each model - albeit broad ranges of them work one way or the other.
    Still not underestimating the power...

    There is no such thing as bad information - There is truth in the data, so you sift it all, even the crap stuff.

  5. #5
    Senior Member streaker69's Avatar
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    Just a word of caution about doing this. Follow all the instructions carefully. Doing this incorrectly can permanently brick your router.
    A third party security audit is the IT equivalent of a colonoscopy. It's long, intrusive, very uncomfortable, and when it's done, you'll have seen things you really didn't want to see, and you'll never forget that you've had one.

  6. #6
    Senior Member SephStorm's Avatar
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    I appreciate the polite replies, I half expected someone to tell me to complete my research before I posted. I'm just glad Cisco still has docuentation for this router, apparently it's quite old.
    "You're only smoke and mirrors..."

  7. #7
    My life is this forum Barry's Avatar
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    Quote Originally Posted by SephStorm View Post
    I appreciate the polite replies, I half expected someone to tell me to complete my research before I posted. I'm just glad Cisco still has docuentation for this router, apparently it's quite old.
    It's the way you asked you question. It didn't come off as some high school kid screwing with his school's network. I also think you would have gotten different answers if this was your first post.

  8. #8
    Senior Member streaker69's Avatar
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    Quote Originally Posted by Barry View Post
    It's the way you asked you question. It didn't come off as some high school kid screwing with his school's network. I also think you would have gotten different answers if this was your first post.
    Plus not many actually come here asking how to reset something back to factory defaults, normally it's the question about how do you reset it if you don't have access to it.
    A third party security audit is the IT equivalent of a colonoscopy. It's long, intrusive, very uncomfortable, and when it's done, you'll have seen things you really didn't want to see, and you'll never forget that you've had one.

  9. #9
    Senior Member SephStorm's Avatar
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    Good points. Thanks again.
    "You're only smoke and mirrors..."

  10. #10
    Senior Member secure_it's Avatar
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    Take a statup config. backup for sure as bypassing NVRAM contains will also bypass startup config which contains all the router config.

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