Networking/Password Recovery at main · nicbrinkley/Networking · GitHub

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Cisco 3650, 3850, catalyst 9300 Switch password recovery
• Press "Mode" button as soon as the SYST light starts flashing green and you get switch into "switch:" mode.
switch: flash_init
switch: SWITCH_IGNORE_STARTUP_CFG=1
switch: boot
• From Switch> prompt, enter Enable mode (switch#) and then copy startup-config to running-config.. NOT run to start like you usually do, or you'll loose your configuration!
switch# copy startup-config running-config
• Fix the password or login issue you're having and save config.
• Now reboot the switch, get back into switch: mode, and fix the boot variable back to Zero.
switch: flash_init
switch: SWITCH_IGNORE_STARTUP_CFG=0
switch: boot

Alternatively to going back into the switch: prompt, some software versions also support the configuration command:
(config)#no system ignore startupconfig switch all
(config)#end
#write mem
Perform a reload and check the switch


Cisco Router IOS password recovery
• Use the Ctrl + Break function to get the router into Rommon as soon as router is power-cycled.
• Change the config-register variable to 0x2142 so the router will ignore the startup config in NVRAM, and then reboot the router.
monitor: command "boot" aborted due to user interrupt
rommon 1 >
rommon 1 > confreg 0x2142
• You must reset or power cycle for new config to take effect
rommon 2 > reset
• Router will boot without a config.  From the Router> prompt, enter Enable mode, and then copy startup config to running config.
Would you like to enter the initial configuration dialog? [yes/no]: no

Press RETURN to get started!

Router>en
Router#copy startup-config running-config
Destination filename [running-config]?

5413 bytes copied in 5.325 secs (1017 bytes/sec)
Old_Lab_Router#
• Now fix your password or login issue, save the config and reboot... then get router back into Rommon and set config-register to 0x2102
monitor: command "boot" aborted due to user interrupt
rommon 1 > confreg 0x2102

You must reset or power cycle for new config to take effect
rommon 2 > reset

Router will then reboot and load the saved config,  and now you'll be able to get into it this time, because you'll have fixed your password or login issue!

Steps for most older Cisco switches:
Coming Soon...