Analysis of Cisco Router password restoration principles

Vro is one of the hardware devices that network administrators often need to deal with. If you forget the vro password, you will be given two tips to solve the Cisco password problem.
The boot options in Cisco IOS software need to understand some knowledge about Cisco IOS software before restoring the Cisco Router password, especially the boot options will be used in subsequent password recovery. You can guide the ISO software in the Cisco Series in three ways. Flash memory (www.2cto.com) allows you to copy a system image without modifying the electroerasable read-only programming memory (EEPROM ). When a system image is loaded from the TFTP server, the information stored in the flash storage will not be lost. Router # configure terminal router # (config) # boot system flash gsner-image [Ctrl-Z] router # copy running-config startup-config network server) router # configure terminal router # (config) # boot system tftp test.exe 172.16.13.111 [Ctrl-Z] router # copy running-config startup-config ROM if the flash memory crashes and the network server cannot load the system image, start the system from the ROM. the last boot option in the software. However, System Images in the ROM may be a subset of Cisco IOS software, but lack the protocols, attributes, and configurations required for the complete Cisco ISO software. If you have upgraded the software after purchasing the router, it may also be an older version of Cisco IOS software. Router # configure terminal router # (config) # boot system rom [Ctrl-Z] router # copy running-config startup-config
The password recovery principle of a Cisco router is www.2cto.com. The Cisco router can save several different configuration parameters and store them in different memory modules. Taking the Cisco 2500 series as an example, its Memory includes ROM. Flash Memory, immutable RAM, RAM, and dynamic Memory (DRAM. Generally, when a vrodram is started, the system first runs the program in ROM for self-check and boot, then runs IOS in flash memory, searches for vro configuration in NVRAM, and loads it into DRAM. The key to password recovery is to modify the Configuration RegisterValue so that the vro can call different parameter tables from different memories for start-up. Valid passwords are stored in NVRAM. Therefore, the essence of password modification is to modify the registration code, in this way, the vro skips the configuration table in NVRAM and directly enters the ROM mode. Then, modify the valid password and terminal password, or reset the valid encryption password. Then, the registration code is restored. Enabled secret password: the highest security level of the encrypted password appears in the vro configuration table as a password; enabled password) A non-encrypted password with a high security level. This password is used when no valid password is set. The terminal password (enabled password ). this password is used to prevent unauthorized or unauthorized users from modifying the Cisco vro password. It is used when you set the vro through the main control terminal. This article is from the fat shark network.