Password recovery methods for Cisco routers

1, start the router, during the startup process, press and hold the "Ctrl+break" key. The system then enters the disaster recovery mode with the prompt:

Rommon 1 >

2, modify the register value of 0x2142

Rommon 2 >confreg 0x2142

3, restart the router, after reboot due to no longer read the NVRAM in the configuration file

Rommon 3 >reset

3, into the privileged mode, the Naram in the configuration file loaded into RAM

Router#copy Startup-config Running-config

4, enter the global configuration mode, modify or delete password

Router (config) #enable password [password]

Router (config) #enable secret [password]

Router (config) #no enable password

Router (config) #no enable secret

5, the value of the Restore register is 0x2102

Router (config) #config-register 0x2102

6, Save the modified configuration

Router#copy Running-config Startup-config

Ps:

Configure Register Value command: Config-register

The register value is a total of 16 digits and is represented by a 4-bit 16 binary number.

Format: 0xABCD assignment range from 0x0 to 0xFFFF

0X2102: Standard default values

0x2142: Starting from flash, but not using the configuration file in NVRAM (for password recovery)

0X2101: Booting from boot RAM, applied to update system files

0x2141: Starting from boot RAM, but not using the configuration file in NVRAM

Where the third digit of the C bit is 1, the break key is turned off, whereas the break key is turned on.

0x141: Closes the break key, does not use the configuration file in Nvram, and starts from a system in the system's default ROM.

0X0040: Indicates that the router is allowed to read configuration files in NVRAM.

What you mean in Config-register

bit hexadecimal value meaning

00-03 0x0000-0x000f Boot bit

0X0020 uses an extended console rate of over 19200bps

0X0040 enables system software to ignore content in NVRAM

Modified 0x0080 OEM bit Open

The 0x0100 break key closes

Ten 0x0400 IP broadcasts to all domains

11-12 0x0800-0x1000 Console Port rate

0x2000 If network startup fails, default starts from ROM

0x4000 IP broadcasts that do not contain a network number

0x8000 Start diagnostic information and ignore NVRAM content

Other:

Cisco Official Simulator Packet Tracer (PT) currently only simulates the router's password recovery and cannot simulate the switch's password recovery.

This article is from the "Network" blog, please be sure to keep this source http://netlin.blog.51cto.com/118225/959243