Recover the Cisco Router password in ROM Monitor mode

Many users have forgotten their passwords when using vrouters. The following describes how to restore the password of a Cisco vro. For many beginners, the ROM Monitor of Cisco routers is often unfamiliar or even daunting. The reason is very simple. First, we do not often use this mode and are not familiar with its related operations; second, Operation errors in ROM Monitor mode often cause fatal damage To routers, such as destroying IOS files in flash, resulting in system crashes. So many people put their hands on it and are discouraged.

In fact, ROM Monitor is not complex. It is only a low-level operating system of the Cisco router, which is usually used for testing and troubleshooting. It can be done easily with little time. The following describes how to use ROM Monitor, which is the two most common problems for network administrators in actual work. To prevent others from knowing the vro password, especially the privileged password, and threatening local network security, many administrators have made the password particularly complex. However, after configuring the vro, we seldom operate on the vro. After a while, when we need to configure the vro, the password may be lost. At this time, we only need a PC operating system for the Windows series), a Console cable and the corresponding interface converter, and then follow the following operations, you can easily deal.

1. Set the Super Terminal of the PC so that we can use the Console port of the vro to directly operate the vro because the process is very simple. I will omit it to save space ).

2. Start the vro and press the Break or Ctrl + Break Key in the first 60 seconds to enter the ROM Monitor mode of the vro.

3. The following describes the Cisco 2600 series routers most commonly used by beginners.

In comparison, the second situation is more rare, but also more serious. It often occurs when the router system crashes due to errors in the upgrade of the IOS version or other hardware and software faults, the entire network is paralyzed. At this time, we often need to repair the router in ROM Monitor mode. The following is an example of a student's problem. When the student upgrades the IOS of a Cisco 2600 router, the following fault occurs: After the router cannot determine the IOS file in flash, we need to restore the IOS file from the Cisco Router password in the TFTP Server to the flash of the router. In this case, we can do this in two ways: first, use a PC with the Cisco TFTP Server installed to recover the IOS router over Ethernet, and second, in ROM Monitor mode, xmodem is used to transmit files using the Console cable. Here, we give priority to the first method. The steps are as follows:

1. Connect a PC installed with Cisco TFTP Server to the Ethernet interface of the router through Ethernet to run the Cisco TFTP Server program.
 
2. Use a Super Terminal to log on to the Console of the vroconsole. The Console router is started and logged on when a fault is found. The terminal screen is shown as follows:
 
Rommon 2> set
This command displays vro related default settings
PS1 = rommon! >
IP_ADDRESS = 192.168.1.1
IP_SUBNET_MASK = 255.255.255.0
DEFAULT_GATEWAY = 192.168.1.2
TFTP_SERVER = 192.168.1.2
TFTP_TIMEOUT = 20000
TFTP_RETRY_COUNT = 10
TFTP_FILE =/c2600-ik8o3s-mz.122-11.T/

3. check the default vro settings and change the IP address of the PC to 192.168.1.2. We can also use the command TFTP_SERVER = 192.168.1.x to modify the settings, make sure that the IP address of the router, the default gateway, and the IP address of the PC are in the same CIDR block.

4. specify the name of the IOS file for which the Cisco Router password is restored, and ensure that the file is under the root directory of the Cisco TFTP Server. Rommon 3> TFTP_FILE =/c2600-i-mz.121-3.T.bin do not forget to add extension file name. bin

5. Start to restore the IOS file using the Cisco Router password:

Rommon 4> tftpdnld
Run this command to download the IOS file from the TFTF Server to flash. This command is only applicable to Cisco 2600 series routers.
IP_ADDRESS: 192.168.1.1
IP_SUBNET_MASK: 255.255.255.0
DEFAULT_GATEWAY: 192.168.1.2
TFTP_SERVER: 192.168.1.2
TFTP_FILE:/c2600-i-mz.121-3.T.bin
Invoke this command for disaster recovery only.
WARNING: all existing data in all partitions on flash will be lost!
Do you wish to continue? Y/n: [n]: y
Refreshing ing/c2600-i-mz.121-3.T.bin from 192.168.1.2
File completion tion completed.
Copying file/c2600-i-mz.121-3.T.bin to flash.
Erasing flash at 0x60fc0000
Program flash location 0x60160000

6. Restart the router and run the new IOS, rommon 5> reset