Break Key Sequence For Password Recovery in Cisco Router or Switch

If you forgot the password to your Cisco router,  The fastest solution is to  replace the Router or Switch is password recovery option. During the password recovery procedure, it is fundamental sent the correct ‘Break’ key sequence to login ROMMON mode, but, as you know, the ‘break’ sequence depends by the operating System and Terminal emulator software that you use on your personal computer.You need to access the router physically and plugged console cable to console port directly. The break key combinations is to login to ROMMON mode without password authentication. You can recover the lost password from Rommon Mode easily.

Below the standard break key sequence combinations for the most common operating systems.

Software Platform Operating System Try This
Hyperterminal IBM Compatible Windows XP Ctrl-Break
Hyperterminal IBM Compatible Windows 2000 Ctrl-Break
Hyperterminal IBM Compatible Windows 98 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
SecureCRT IBM Compatible Windows Ctrl-Break
Telix IBM Compatible DOS Ctrl-End
Telnet N/A N/A Ctrl-], then type ‘send brk’
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

Simulate a Break Key Sequence on Cisco Router or Switch

What can I do if I have tried all these sequence and nothing happens? It’s easy! You can simulate the ‘break’ key!

Break key sequence simulation is useful if your terminal emulator does not support the break key, or if a bug does not allow your terminal emulator to send the correct signal.

Complete these steps to simulate a break key sequence:

  1. Connect to the router with these terminal settings:
    • 1200 baud rate
    • No parity
    • 8 data bits
    • 1 stop bit
    • No flow control
    • You no longer see any output on your screen, and this is normal.
  2. Power cycle (switch off and then on) the router and press the SPACEBAR for 10-15 seconds in order to generate a signal similar to the break sequence.
  3. Disconnect your terminal, and reconnect with a 9600 baud rate. You enter the ROM Monitor mode.

Remember: The Electronic Industries Association leavingcisco.com RS-232 logic level uses +3 to +25 volts to signify a Space (Logic 0) and -3 to -25 volts for a Mark (logic 1). A break signal is when the data line remains in the space condition for a specified duration, usually 100 ms to ½ second. All characters begin with a start bit and end with a stop bit (and also a parity bit or two). The level condition of the start and stop bits is always opposite. So, no character combination can look like the break signal.
Remember: In some cases, the break sequence might not get transmitted properly when using a USB/Serial converter cable. In such cases, use a keyboard with a different connector port (for example, a PS/2).

 

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  1. Eva says:

    Hey, nice post on Password recovery break key sequence on cisco Router and Switch. I never heard of that before. Thanks. Bye, Eva.

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