If you are using putty with serial port. To access rommon mode press
Ctrl + Shift + Break or Pause.
And if you are using Terra Term with serial port press
Alt + B
Configure aux 0 for reverse telnet.
conf term line aux 0 modem InOut transport input all exit !
How to find line number for aux 0
R01#show line
Tty Line Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
0 0 CTY - - - - - 0 0 0/0 -
* 1 1 AUX 9600/9600 - inout - - - 0 0 0/0 -
* 514 514 VTY - - - - 50 1 0 0/0 -
515 515 VTY - - - - 50 0 0 0/0 -
!
Now that found line number for aux 0 is line number 1.
IP address of the router 2000 + line number 1
Is telnet 10.1.1.1 2001
R01#telnet 10.1.1.1 2001 Trying 10.1.1.1, 2001 ... % Connection refused by remote host R01#clear line 1 [confirm] [OK] R01#telnet 10.1.1.1 2001 Trying 10.1.1.1, 2001 ... Open User Access Verification Username: admin Password: PPPOE# PPPOE# PPPOE#
Then what to do with reverse telnet how to access rommon mode ?
( Ctrl + Shift + 6 ) release and then press B
System Bootstrap, Version 12.4(13r)T11, RELEASE SOFTWARE (fc1) Technical Support: http://www.cisco.com/techsupport Copyright (c) 2009 by cisco Systems, Inc. Initializing memory for ECC . c2811 platform with 262144 Kbytes of main memory Main memory is configured to 64 bit mode with ECC enabled Upgrade ROMMON initialized PC = 0xbfcd0d54, Cause = 0x2000, Status Reg = 0x3040a803 monitor: command "boot" aborted due to user interrupt rommon 1 > rommon 1 > rommon 1 > rommon 1 > confreg 0x2142 You must reset or power cycle for new config to take effect rommon 2 > reset
After reset.
Router>en Router#copy start running-config Destination filename [running-config]? 2991 bytes copied in 12.400 secs (241 bytes/sec) PPPOE# PPPOE#conf term Enter configuration commands, one per line. End with CNTL/Z. PPPOE(config)#config 0x2102 PPPOE(config)#end PPPOE# *Apr 30 04:55:47.419: %SYS-5-CONFIG_I: Configured from console by console PPPOE#show version Configuration register is 0x2142 (will be 0x2102 at next reload) PPPOE#
Then to exit reverse telnet.
( Ctrl + Shift + 6) release and then press X
https://networklessons.com/network-services/cisco-terminal-server-configuration-example/
http://ciscofaq.blogspot.com/2005/05/how-to-i-reverse-telnet-out-my-aux.html
https://supportforums.cisco.com/discussion/10680346/me-3400-password-recovery