1.     Password Recovery!

2.     DHCP on Cisco Routers

 

 

Standard Break Key Combinations

Software

Platform

Operating System

Try This

Hyperterminal

IBM Compatible

Windows 2000

Ctrl-Break

Hyperterminal (version 595160)

IBM Compatible

Windows 95

Ctrl-F6-Break

Kermit

Sun Workstation

UNIX

Ctrl-\l

Ctrl-\b

MicroPhone Pro

IBM Compatible

Windows

Ctrl-Break

Minicom

IBM Compatible

Linux

Ctrl-a f

ProComm Plus

IBM Compatible

DOS or Windows

Alt-b

Telix

IBM Compatible

DOS

Ctrl-End

Telnet to Cisco

IBM Compatible

N/A

Ctrl-]

Teraterm

IBM Compatible

Windows

Alt-b

Terminal

IBM Compatible

Windows

Break

Ctrl-Break

Tip

Sun Workstation

UNIX

Ctrl-], then Break or Ctrl-c

~#

VT 100 Emulation

Data General

N/A

F16

Windows NT

IBM Compatible

Windows

Break-F5

Shift-F5

Shift-6 Shift-4 Shift-b (^$B)

Z-TERMINAL

Mac

Apple

Command-b

N/A

Break-Out Box

N/A

Connect pin 2 (X-mit) to +V for half a second

Cisco to aux port

N/A

Control-Shft-6, then b

IBM Compatible

N/A

Ctrl-Break

 


Cisco Password Recovery

 

Description

This document describes the password recovery procedure for Cisco 801, 802, 803, 804, and 805 routers.

To recover a password on a Cisco 806 or 827 router, click here.

Step-by-Step Procedure

  1. Attach a terminal or PC with terminal emulation to the console port of the router. Use the following terminal settings:

9600 baud rate
No parity
8 data bits
1 stop bit

The required console cable specifications are described in Cabling Guide for RJ-45 Console and AUX Ports (Cisco's 1000 series, 2500 series, and AS5100).

  1. Using the power switch, turn the router off and then turn it back on.
  2. Press Break on the terminal keyboard within 60 seconds of the power-up to put the router into ROMMON.

If the break sequence doesn't work, see Possible Key Combinations for Break Sequence During Password Recovery for other key combinations.

  1. Type set at the boot# prompt and record the current value of the config register (set by the "ios-conf" variable)
5.                 boot# set 
6.                 set baud           =9600 
7.                 set data-bits      =8 
8.                 set parity         =none     
9.                 set stop-bits      =1 
10.             set console-flags  =0 
11.             set mac-address    =0050.7307.C329 
12.             set unit-ip        =10.200.40.65      
13.             set serv-ip        =255.255.255.255      
14.             set netmask        =255.255.252.0      
15.             set gate-ip        =10.200.40.1     
16.             set pkt-timeout    =8 
17.             set tftp-timeout   =16 
18.             set boot-action    =flash
19.             set file-name      ="c800-oy6-mw.120-5.T"      
20.             set watchdog       =off 
21.             set prompt         ="boot"      
set ios-conf       =0x2102    !-- this is the value to record
  1. Type set ios-conf = 142 at the boot# prompt.

If Flash is intact, the best setting is 142.

If the Flash is not installed or is erased, use the 141 setting. Note: With this setting you can view or erase the configuration, but you cannot change the password.

  1. Type boot at the boot#> prompt to initialize the router.

The router reboots but ignores its saved configuration.

  1. Type no after each setup question or press Ctrl-C to skip the initial setup procedure.
  2. Type enable at the Router> prompt.

You'll be in enable mode and see the Router# prompt.

  1. Important: Type config mem or copy start running to copy the nonvolatile RAM (NVRAM) into memory. Do not type config term.
  2. Type wr term or show running.

The show running and wr term commands show the configuration of the router. In this configuration you see under all the interfaces the shutdown command, which means all interfaces are currently shutdown. Also, you can see the passwords either in encrypted or unencrypted format.

  1. Type config term and make the changes.

The prompt is now hostname(config)#.

  1. Type enable secret <password>.
  2. Issue the no shutdown command on every interface that is used. If you issue a show ip interface brief command, every interface that you want to use should be "up up".
  3. Type config-register 0x2102, or the value you recorded in step 2.
  4. Press Ctrl-z to leave the configuration mode.

The prompt is now hostname#.

  1. Type write mem or copy running startup to commit the changes.
17.       Router>show version
18.       Cisco Internetwork Operating System Software
19.       IOS (tm) C800 Software (C800-Y6-MW), Version 12.1(1), RELEASE SOFTWARE (fc1)
20.       Copyright (c) 1986-2000 by cisco Systems, Inc.
21.       Compiled Tue 14-Mar-00 16:01 by cmong
22.       Image text-base: 0x000EA000, data-base: 0x005D3000
23.        
24.       ROM: TinyROM version 1.0(3)
25.       Router uptime is 2 days, 3 hours, 8 minutes
26.       System returned to ROM by power-on
27.       System image file is "flash:c800-y6-mw.121-1"
28.        
29.       Cisco C801 (MPC850) processor (revision 0) with 51428K bytes of virtual memory.
30.       Processor board ID JAD03050229
31.       CPU part number 33
32.       Bridging software.
33.       Basic Rate ISDN software, Version 1.1.
34.       1 Ethernet/IEEE 802.3 interface(s)
35.       1 ISDN Basic Rate interface(s)
36.       12M bytes of physical memory (DRAM)
37.       8K bytes of non-volatile configuration memory
38.       8M bytes of flash on board (4M from flash card)
39.        
40.       Configuration register is 0x2102
41.        
42.       !--- The router was just powercycled and during
43.       bootup a break sequence was sent to the router.
44.        
45.       TinyROM version 1.0(3)
46.       Fri Apr 30 18:22:12 1999
47.       Copyright (c) 1998-1999 by cisco Systems, Inc.
48.       All rights reserved.
49.        
50.       POST ......... OK. 12MB DRAM, 8MB Flash.
51.        
52.       boot# set ios-conf = 142
53.       boot# boot
54.        
55.       Booting "c800-y6-mw.121-1" ...,
56.               Restricted Rights Legend
57.        
58.       Use, duplication, or disclosure by the Government is 
59.       subject to restrictions as set forth in subparagraph
60.       (c) of the Commercial Computer Software - Restricted
61.       Rights clause at FAR sec. 52.227-19 and subparagraph
62.       (c) (1) (ii) of the Rights in Technical Data and Computer
63.       Software clause at DFARS sec. 252.227-7013.
64.        
65.             cisco Systems, Inc.
66.             170 West Tasman Drive
67.             San Jose, California 95134-1706
68.        
69.       Cisco Internetwork Operating System Software
70.       IOS (tm) C800 Software (C800-Y6-MW), Version
71.       12.1(1), RELEASE SOFTWARE (fc1)
72.       Copyright (c) 1986-2000 by cisco Systems, Inc.
73.       Compiled Tue 14-Mar-00 16:01 by cmong
74.       Image text-base: 0x000EA000, data-base: 0x005D3000
75.        
76.       Cisco C801 (MPC850) processor (revision 0) with 51428K bytes of virtual memory.
77.       Processor board ID JAD03050229
78.       CPU part number 33
79.       Bridging software.
80.       Basic Rate ISDN software, Version 1.1.
81.       1 Ethernet/IEEE 802.3 interface(s)
82.       1 ISDN Basic Rate interface(s)
83.       12M bytes of physical memory (DRAM)
84.       8K bytes of non-volatile configuration memory
85.       8M bytes of flash on board (4M from flash card)
86.        
87.        
88.           --- System Configuration Dialog ---
89.        
90.       Would you like to enter the initial configuration dialog? [yes/no]: n
91.        
92.        
93.       Press RETURN to get started! (press Enter)
94.        
95.       00:01:45: %SYS-5-RESTART: System restarted --
96.       Cisco Internetwork Operating System Software
97.       IOS (tm) C800 Software (C800-Y6-MW), Version 12.1(1), RELEASE SOFTWARE (fc1)
98.       Copyright (c) 1986-2000 by cisco Systems, Inc.
99.       Compiled Tue 14-Mar-00 16:01 cmong
100.   00:01:45: %LINK-5-CHANGED: Interface BRI0, changed state to administratively down 
101.   00:01:45: %LINK-5-CHANGED: Interface Ethernet0, changed state to administratively down 
102.   00:01:46: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0, changed state to down 
103.   00:01:46: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0, changed state to down 
104.   Router>en
105.   Router#copy start run
106.   Destination filename [running-config]? (press Enter)
107.   2010 bytes copied in 32.120 secs (62 bytes/sec)
108.   Router#
109.   Router#
110.   00:02:53: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state to down
111.   00:02:53: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:2, changed state to down
112.   Router#conf t
113.   Enter configuration commands, one per line. End with CNTL/Z.
114.   Router(config)#enable secret cisco
115.   Router(config)#
116.   00:03:39: %SYS-5-CONFIG_I: Configured from console by console
117.    
118.   Router#sh ip int brief 
119.   Interface   IP-Address      OK?    Method   Status                 Protocol
120.   BRI0        unassigned      YES    TFTP     administratively down  down
121.   BRI0:1      unassigned      YES    unset    administratively down  down
122.   BRI0:2      unassigned      YES    unset    administratively down  down
123.   Dialer0     unassigned      YES    TFTP     up                     up 
124.   Dialer1     192.168.32.1    YES    TFTP     up                     up
125.   Ethernet0   10.200.40.65    YES    TFTP     administratively down  down
126.   Router#conf t
127.   Enter configuration commands, one per line. End with CNTL/Z.
128.   Router(config)#int e 0
129.   Router(config-if)#no shut
130.   Router(config-if)#
131.   00:04:02: %LINK-3-UPDOWN: Interface Ethernet0, changed state to up
132.   00:04:03: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0, changed state to up
133.   Router(config)#config-reg 0x2102
134.   Router(config)#^Z
135.   Router#
136.   00:04:36: %SYS-5-CONFIG_I: Configured from console by console
137.   Router#write mem

 

Cisco 802     IOS 12.0 (5)

DHCP on Cisco Routers

ip dhcp-server

To specify which Dynamic Host Configuration Protocol (DHCP) servers to use on your network, specify the IP address of one or more DHCP servers available on the network, use the ip dhcp-server global configuration command. Use the no form of the command to remove a DHCP server's IP address.

ip dhcp-server [ip-address | name]
no ip dhcp-server [ip-address | name]

Syntax Description

ip-address

(Optional) IP address of a DHCP server.

name

(Optional) Name of a DHCP server.

 

 

Default

The IP limited broadcast address of 255.255.255.255 is used for transactions if no DHCP server is specified. This allows automatic detection of DHCP servers.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0.

A DHCP server temporarily allocates network addresses to clients through the access server on an as-needed basis. While the client is active, the address is automatically renewed in a minimum of 20-minute increments. When the user terminates the session, the interface connection is terminated so that network resources can be quickly reused. You can specify up to ten servers on the network.

In normal situations, if a user's SLIP/PPP session fails (for example if a modem line disconnects), the allocated address will be reserved temporarily to preserve the same IP address for the client when dialed back into the server. This way, the session that was accidentally terminated can often be resumed.

To use the DHCP proxy-client feature, enable your access server to be a proxy-client on asynchronous interfaces by using the ip address-pool dhcp-proxy-client command. If you wish to specify which DHCP servers are used on your network, use the ip dhcp-server command to define up to ten specific DHCP servers.


Note To facilitate transmission, configure intermediary routers (or access servers with router functionality) to use an IP helper address whenever the DHCP server is not on the local LAN and the access server is using broadcasts to interact with the DHCP server. See "Configuring IP Addressing" in the Network Protocols Configuration Guide, Part 1.


The ip address-pool dhcp-proxy-client command initializes proxy-client status to all interfaces defined as asynchronous on the access server. To selectively disable proxy-client status on a single asynchronous interface, use the no peer default ip address interface command.

Example

The following command specifies a DHCP server with the IP address of 129.12.13.81:

ip dhcp-server 129.12.13.81

Related Commands

You can use the master indexes or search online to find documentation of related commands.

ip address-pool dhcp-proxy-client
ip helper address

peer default ip address pool
show dhcp

ip local pool

To configure a local pool of IP addresses to be used when a remote peer connects to a point-to-point interface, or to add a range of addresses to an existing pool, use the ip local pool global configuration command. To remove an address pool, or a range of addresses from a pool, use the appropriate no form of this command.

ip local pool {default | pool-name} low-ip-address [high-ip-address]
no ip local pool {default | pool-name}
no ip local pool {default | pool-name} low-ip-address [high-ip-address]


Note There are two ways to use the ip local pool command and its no forms; see the usage guidelines and examples for more explanation of use.


Syntax Description

default

Default local address pool that is used if no other pool is named.

pool-name

Name of a specific local address pool. (Always use the pool-name argument consistently.)

low-ip-address

Lowest IP address in the pool.

high-ip-address

(Optional) Highest IP address in the pool. If this value is omitted only the low-ip-address IP address is included in the local pool.

 

 

Default

No address pools are configured.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0. Enhancements to the command were made in Releases 11.3AA and 12.0, to support multiple address ranges.

Use the ip local pool command to create one or more local address pools from which IP addresses are assigned when a peer connects. The default address pool is then used on all point-to-point interfaces after the ip address-pool local global configuration command is issued. To use a specific, named address pool on an interface, use the peer default ip address pool interface configuration command.

Use the shorter no form of the command to remove the entire address pool (default or specific).Use the longer no form of the command with appropriate keywords and arguments to remove a range of addresses from a pool.

These pools can also be used with the translate commands for one-step vty-async connections and in certain AAA/TACACS+ authorization functions. Refer to the "Configuring Protocol Translation and Virtual Asynchronous Devices" chapter in the Dial Solutions Configuration Guide and the "System Management" part of the Configuration Fundamentals Configuration Guide for more information. Pools can be displayed with the show ip local pool command.

Example

The following command creates a local IP address pool by the name of quark, which contains all local IP addresses from 172.16.23.0 to 172.16.23.255:

ip local pool quark 172.16.23.0 172.16.23.255
 

The following example configures a pool of 1024 IP addresses:

 2511(config)#no ip local pool default
 2511(config)#ip local pool default 1.1.1.0 1.1.4.255
 2511(config)#^Z
 2511#show ip local pool
  Pool     Begin           End             Free InUse
  default  1.1.1.0         1.1.4.255       1024  0
 

The following example configures multiple ranges of IP addresses into one pool:

 7206-9(config)#no ip local pool default
 7206-9(config)#ip local pool default 9.1.1.0 9.1.9.255
 7206-9(config)#ip local pool default 9.2.1.0 9.2.9.255
 7206-9(config)#^Z

 
 7206-9#show ip local pool
  Pool     Begin           End             Free    In use   Cache Size
  default  9.1.1.0         9.1.9.255       2304       0          20
           9.2.1.0         9.2.9.255       2304       0
 

Related Commands

You can use the master indexes or search online to find documentation of related commands.

ip address-pool
show ip local pool