拓扑图：
1 配置任何特权加密码并保存Router>enable Router#config t Enter configuration commands, one per line. End with CNTL/Z.Router(config)#hostname R1R1(config)#interface g 0/0 R1(config-if)#ip address 192.168.1.1 255.255.255.0 R1(config-if)#no shutdownR1(config-if)#enable secret asdf%LINK-5-CHANGED: Interface GigabitEthernet0/0, changed state to upR1(config)#exitR1#%SYS-5-CONFIG_I: Configured from console by consoleR1#wrBuilding configuration...[OK]R1#2 重启路由器reload3 在加载系统的过程中， 使用 Ctrl Break 键或者 Ctrl C 键，修改 confreg寄存器的值，使路由器绕过配置文件进入系统
rommon 1 > helpboot boot up an external processconfreg configuration register utilitydir list files in file systemhelp monitor builtin command helpreset system resetset display the monitor variablestftpdnld tftp image downloadunset unset a monitor variablerommon 2 > confreg 0x2142rommon 3 > reset4 此时无需输入密码即可进入系统，此时，我们重新配置密码。配置密码完成后，修改confreg引导系统正常启动寄存器值。
Router>enRouter#config tEnter configuration commands, one per line. End with CNTL/Z.Router(config)#hostname R1R1(config)#enable secR1(config)#enable secret 123abcR1(config)#config-register 0x2102R1(config)#endR1#%SYS-5-CONFIG_I: Configured from console by consoleR1#wrBuilding configuration...[OK]5 最后重启reload
