4507/4503/4506等4500系列交換機密碼恢復的詳細過程，雖然4500系列已經很老了，但是難免會再次遇到，記錄一下。

1，重啟設備
關閉設備電源后，重新打開。在5秒內按Ctrl-C以防止自動引導。
!— 重啟設備
**********************************************************
* *
* Welcome to ROM Monitor for WS-X4014 System. *
* Copyright (c) 1999-2000, 2001 by Cisco Systems, Inc. *
* All rights reserved. *
* *
**********************************************************

ROM Monitor Program Version 12.1(10r)EY(1.21)

Board type 1, Board revision 7
Swamp FPGA revision 16, Dagobah FPGA revision 43

Timer interrupt test passed.

MAC Address : 00-02-b9-83-af-fe
IP Address : 172.16.84.122
Netmask : 255.255.255.0
Gateway : 172.16.84.1
TftpServer : Not set.
Main Memory : 256 MBytes

***** The system will autoboot in 5 seconds *****

Type control-C to prevent autobooting.
!— 按住 Ctrl-C.

Autoboot cancelled……… please wait!!!
Autoboot cancelled……… please wait!!!
rommon 1 > [interrupt]
rommon 1 > [interrupt]

2，在rommon提示符下使用confreg命令忽略從原配置啟動
rommon 1 > set
rommon 1 > confreg
Configuration Summary :
=> load ROM after netboot fails
=> console baud: 9600
=> autoboot from: commands specified in ‘BOOT’ environment variable
do you wish to change the configuration? y/n [n]: y
enable “diagnostic mode”? y/n [n]: n
enable “use net in IP bcast address”? y/n [n]: n
disable “load ROM after netboot fails”? y/n [n]: n
enable “use all zero broadcast”? y/n [n]: n
enable “break/abort has effect”? y/n [n]: n
enable “ignore system config info”? y/n [n]: y
change console baud rate? y/n [n]: n
change the boot characteristics? y/n [n]: n

Configuration Summary :
=> load ROM after netboot fails
=> ignore system config info
=> console baud: 9600
=> autoboot from: commands specified in ‘BOOT’ environment variable
do you wish to save this configuration? y/n [n]: y
You must reset or power cycle for new configuration to take effect

rommon 1 >confreg 0x2142
You must reset or power cycle for the new configuration to take effect.

3，重啟設備
rommon 2 > reset
Resetting …….

rommon 3 >
**********************************************************
* *
* Welcome to ROM Monitor for WS-X4014 System. *
* Copyright (c) 1999-2000, 2001 by Cisco Systems, Inc. *
* All rights reserved. *
* *
**********************************************************

Press RETURN to get started!

00:00:21: %SYS-5-RESTART: System restarted —
Cisco Internetwork Operating System Software
IOS ™ Catalyst 4000 L3 Switch Software (cat4000-IS-M),
Version 12.1(8a)EW, RELEASE SOFTWARE (fc1)
TAC Support: http://www.cisco.com/tac
Copyright (c) 1986-2002 by cisco Systems, Inc.
Compiled Thu 24-Jan-02 17:34 by ccai
00:00:21: %SNMP-5-COLDSTART: SNMP agent on host Switch
is undergoing a cold start
Switch>

4，確保設備寄存值為0x2142
此值使設備從Flash啟動，而無需加載已保存的配置。在Switch提示符下發出enable命令進入啟用模式。然后，使用show version命令以檢查配置寄存器值。
Switch> enable
Switch#show version
Cisco Internetwork Operating System Software
IOS (TM) Catalyst 4000 L3 Switch Software (cat4000-IS-M),
Version 12.1(8a)EW, RELEASE SOFTWARE (fc1)
TAC Support: http://www.cisco.com/tac
Copyright (c) 1986-2002 by cisco Systems, Inc.
Compiled Thu 24-Jan-02 17:34 by ccai
Image text-base: 0x00000000, data-base: 0x00AA2B8C

ROM: 12.1(10r)EY(1.21)
Switch uptime is 5 minutes
System returned to ROM by reload
Running default software

cisco WS-C4006 (MPC8245) processor (revision 7) with 262144K bytes of memory.
Processor board ID FOX04183666
Last reset from Reload
32 Gigabit Ethernet/IEEE 802.3 interface(s)
467K bytes of non-volatile configuration memory.

Configuration register is 0x2142

Switch#

5，將配置恢復到內存中
使用configure memory命令或copy startup-config running-config命令將NVRAM復制到內存中。
請勿使用configure terminal命令，該命令顯示模塊的默認配置。
Switch#configure memory
Uncompressed configuration from 1307 bytes to 3014 bytes
Switch#
00:13:52: %SYS-5-CONFIG_I: Configured from memory by console
c-4006-SUPIII#

6，檢查接口狀態
使用show ip interface brief命令以確保之前使用的接口顯示“ up up ”狀態。
如果在密碼恢復之前使用的任何接口顯示“ down ”，請在該接口上發出no shutdown命令以啟動接口。

7，檢查配置
使用write terminal命令和show running-config命令檢查配置。
c-4006-SUPIII#show running-config
Building configuration…
Current configuration : 3014 bytes
!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service compress-config
!
hostname c-4006-SUPIII
!
boot system flash bootflash:
!
vtp mode transparent

line con 0
stopbits 1
line vty 0 4
login
!
end

c-4006-SUPIII#

8，更改密碼
c-4006-SUPIII#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
c-4006-SUPIII(config)#no enable secret
!— 刪除舊enable密碼

c-4006-SUPIII(config)#enable secret xxx
[Choose a strong password with at least one capital letter,
one number, and one special character.]
!— 設置新密碼.同理，也可以刪除舊登錄賬號和密碼，重新配置新賬戶和密碼！
c-4006-SUPIII(config)#no username test1
c-4006-SUPIII(config)#username test2 password xxx

9，確保將配置寄存器值更改回0x2102
c-4006-SUPIII(config)#config-register 0x2102
c-4006-SUPIII(config)# ^Z
c-4006-SUPIII#
00:19:01: %SYS-5-CONFIG_I: Configured from console by console
c-4006-SUPIII#write memory
!— 保存配置

Building configuration…
Compressed configuration from 3061 bytes to 1365 bytes[OK]
c-4006-SUPIII#show version
!— 查看設備寄存值

Cisco Internetwork Operating System Software
IOS (TM) Catalyst 4000 L3 Switch Software (cat4000-IS-M),
Version 12.1(8a)EW, RELEASE SOFTWARE (fc1)
TAC Support: http://www.cisco.com/tac
Copyright (c) 1986-2002 by cisco Systems, Inc.
Compiled Thu 24-Jan-02 17:34 by ccai
Image text-base: 0x00000000, database: 0x00AA2B8C

ROM: 12.1(10r)EY(1.21)
c-4006-SUPIII uptime is 20 minutes
System returned to ROM by reload
Running default software

cisco WS-C4006 (MPC8245) processor (revision 7) with 262144K bytes of memory.
Processor board ID FOX04183666
Last reset from Reload
32 Gigabit Ethernet/IEEE 802.3 interface(s)
467K bytes of nonvolatile configuration memory.

Configuration register is 0x2142 (will be 0x2102 at next reload)

c-4006-SUPIII#

此時，已完成密碼恢復。