Access to the console via AUX port

Often in a network environment, it is needed to manage a router/switch via console, but what can you do if you don’t have a computer with a serial interface? You can use another router!

It is easy to do it.

1) Connect the console interface of the router/switch to the router aux interface using a rollover cable. Rollover cables essentially have one end of the cable wired exactly opposite from the other. As you can see below, this essentially “rolls over” the wires.

2) Configure the router aux interface with the transport input (in my example, I enable the telnet protocol).

Ciscozine(config)#line aux 0
Ciscozine(config-line)#transport input telnet

3) Identify the AUX line using the command ‘show line’

Ciscozine#sh 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  -    -      -    -    -     0      0    0/0      -
*   514  514 VTY              -    -      -    -    -     3      0    0/0      -
    515  515 VTY              -    -      -    -    -     0      0    0/0      -
    516  516 VTY              -    -      -    -    -     0      0    0/0      -
    517  517 VTY              -    -      -    -    -     0      0    0/0      -
    518  518 VTY              -    -      -    -    -     0      0    0/0      -

Line(s) not in async mode -or- with no hardware support:
2-513

Ciscozine#

4) Access to the console via AUX port. To do this, you must telnet the address of the router. The port number is ‘2000+#line‘. In this example is 2001 (2000+1),.

Below the video with the example.

Remember:

  • To exit from the console type CTRL+SHIFT+6, then x.
  • Enter the session number to connect to the corresponding device. However if you hit the return key, you are connected to the current terminal session.
  • To ‘kill’ the session use ‘clear line’ or ‘disconnect’ command on the router.

Note: A good alternative is to make your remote console server using raspberry!

References:

7 COMMENTS

  1. i’m accessing router through aux; but password is not set there ……Can I access that without any password using my console cable???

  2. excuse me, in the command telnet ip + “200”,and port aux, is 200 or 2000? in the video is 200 but u explain 2000

    regards

  3. Hello Fab,
    Great thx for your work!
    I want to know whether the ip adress is for the local router or for the switch/router when you use telnet?

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