How to make your Cisco router a terminal server

On more than one occasion I have needed to access the console port of a switch, but I wasn’t physically there but I did have a router near the unit.  You can easily setup your router to act as a Terminal server, allowing you to use a flat rolled cable between the Router’s AUX port and the switch’s CONSOLE port.  First you need to properly configure your AUX port:

line aux 0
    modem InOut
    transport input all
    stopbits 1
    flowcontrol hardware

Now in order to use this feature, log into your router and do the following:

  • from the command prompt enter: SHOW LINE
  • Find the line number for AUX (in this example it is Line 5)
  • Telnet to the IP address of the router you are logged into, but when you telnet you will need to indicate a specific port.  That port is 2000 + the line number.  So in this example your command would look like this: ‘telnet 172.17.10.1 2005’
  • This will get you access to the remote device
  • When you are finished with the session on the remote device break out with CTRL+ALT+6, followed by x one second later.  If you by chance use SecureCRT for your Telnet sessions you can setup a key map that sends the following ASCII standard for that command ‘\036\px’.  You can read more about this on VanDyke’s SecureCRT Forum.
  • Once you are back in the original device you can return to the remote device by simply pressing the ENTER key.
  • If you are finished with your remote session, you can issue a CLEAR command to close that connection.  In this example the command would be ‘CLEAR LINE 5’

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