Resetting the password on a Cisco 3900 series router involves accessing the router’s configuration and either recovering or resetting the password. This process typically requires physical access to the router and may interrupt network services, so proceed with caution. Below are the general steps to reset the password:
1. Connect to the Router
- Use a console cable to connect your computer to the router’s console port.
- Open a terminal emulation program (e.g., PuTTY, Tera Term, or HyperTerminal) and configure it for:
- Baud rate: 9600
- Data bits: 8
- Parity: None
- Stop bits: 1
- Flow control: None
2. Power Cycle the Router
- Turn off the router.
- Turn it back on while watching the terminal output.
3. Interrupt the Boot Process
- During the boot process, you’ll see a message like:
Press RETURN to get started
- Quickly press the Break key (or Ctrl+Break on some keyboards) to interrupt the boot process and enter ROMMON mode.
4. Change the Configuration Register
- In ROMMON mode, type the following command to change the configuration register and bypass the startup configuration:
confreg 0x2142
- This tells the router to ignore the startup configuration during the next boot.
- Reset the router:
reset
5. Boot the Router
- The router will boot without loading the startup configuration.
- When prompted to enter setup mode, type no.
6. Access Privileged EXEC Mode
- Type
enable
to enter privileged EXEC mode:
Router> enable
Router#
7. Load the Startup Configuration
- Copy the startup configuration into the running configuration:
Router# copy startup-config running-config
8. Reset the Password
- Access global configuration mode:
Router# configure terminal
Router(config)#
- Reset the enable password:
Router(config)# enable secret <new_password>
- Reset the console password (if needed):
Router(config)# line console 0
Router(config-line)# password <new_console_password>
Router(config-line)# login
Router(config-line)# exit
- Reset the VTY (remote access) password (if needed):
Router(config)# line vty 0 4
Router(config-line)# password <new_vty_password>
Router(config-line)# login
Router(config-line)# exit
9. Restore the Configuration Register
- Change the configuration register back to its default value (0x2102):
Router(config)# config-register 0x2102
Router(config)# exit
10. Save the Configuration
- Save the changes to the startup configuration:
Router# write memory
or
Router# copy running-config startup-config
11. Reboot the Router
- Reboot the router to apply the changes:
Router# reload
Important Notes:
- Physical Access Required: You must have physical access to the router to perform these steps.
- Service Interruption: Resetting the password will temporarily interrupt network services.
- Legal Compliance: Ensure you have proper authorization to perform these actions on the router.
If you encounter any issues or need further assistance, feel free to ask!