启动优先：rom-bootstrap-NVRAM-flash-network tftp-rom monitor
寄存器默认设置是0x2142
第三位为0时 进入rom monitor
第五位为0时 不进入setup 向导
由于进入setup 模式可以在不知道密码情况下进入设备
为了安全起见 一般会将寄存器值设置为 0x2102
寄存器设置：
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#config-register 0x2102
密码恢复
如果当管理员忘记密码时 又无法进入setup 模式则需要进入rommon 模式
1:启动中按下ctrl+break键来中断 启动 【ＬＩＮＵＸ公社 】
2:修改配置寄存器以开启第五位(为0x2142)
3:重起
4:进入特权模式
5:将 startup-config 文件复制为 running-config
6：修改密码
7：重设寄存器
8：保存
Self decompressing the image :
#################
monitor: command "boot" aborted due to user interrupt
rommon 1 > confreg 0x2142
rommon 2 > reset
System Bootstrap, Version 12.1(3r)T2, RELEASE SOFTWARE (fc1)
Copyright (c) 2000 by cisco Systems, Inc.
cisco 2811 (MPC860) processor (revision 0x200) with 60416K/5120K bytes of memory
Self decompressing the image :
########################################################################## [OK]
Restricted Rights Legend
Use, duplication, or disclosure by the Government is
subject to restrictions as set forth in subparagraph
(c) of the Commercial Computer Software - Restricted
Rights clause at FAR sec. 52.227-19 and subparagraph
(c) (1) (ii) of the Rights in Technical Data and Computer
Software clause at DFARS sec. 252.227-7013.
cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134-1706
Cisco IOS Software, 2800 Software (C2800NM-ADVIPSERVICESK9-M), Version 12.4(15)T1, RELEASE SOFTWARE (fc2)
Technical Support:
Copyright (c) 1986-2007 by Cisco Systems, Inc.
Compiled Wed 18-Jul-07 06:21 by pt_rel_team
Image text-base: 0x400A925C, data-base: 0x4372CE20
This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and
use. Delivery of Cisco cryptographic products does not imply
third-party authority to import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for
compliance with U.S. and local country laws. By using this product you
agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.
A summary of U.S. laws governing Cisco cryptographic products may be found at:
If you require further assistance please contact us by sending email to
export@cisco.com.
cisco 2811 (MPC860) processor (revision 0x200) with 60416K/5120K bytes of memory
Processor board ID JAD05190MTZ (4292891495)
M860 processor: part number 0, mask 49
2 FastEthernet/IEEE 802.3 interface(s)
239K bytes of non-volatile configuration memory.
62720K bytes of ATA CompactFlash (Read/Write)
Cisco IOS Software, 2800 Software (C2800NM-ADVIPSERVICESK9-M), Version 12.4(15)T1, RELEASE SOFTWARE (fc2)
Technical Support:
Copyright (c) 1986-2007 by Cisco Systems, Inc.
Compiled Wed 18-Jul-07 06:21 by pt_rel_team
--- System Configuration Dialog ---
Continue with configuration dialog? [yes/no]: n
Press RETURN to get started!
Router>en
Router#copy startup-config running-config
Destination filename [running-config]?
357 bytes copied in 0.416 secs (858 bytes/sec)
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#no enable password
Router(config)#config-register 0x2102
Router(config)#exit
%SYS-5-CONFIG_I: Configured from console by console
Router#write memory
Building configuration...
[OK]
Router#