Dec
7
2010

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.

References:

Summary
Access to the console via AUX port
Article Name
Access to the console via AUX port
Description
What can you do if you don't have a computer with a serial interface? You can use another router!
Author
  • Franz

    WOW!!!!!! I TRIED!! VERY GOOD!!!

    THANKS TO YOUR BLOG!!

  • max

    Why we need to manage a router/switch via console ? if we have connect to the router from telnet

  • In case of emergency situation: for instance when you have wrong the configuration and you can’t access to the terminal via telnet.

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

  • Yes, you can access to console via aux without a password

  • Yhor

    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

  • Hi, how you can see in the video the port is 2000 + the port number. For instance, if you line is ‘1’, you have to telnet the tcp port 2001 (2000 + #line)

  • You need telnet a physical or virtual internface (you can use a loopback interface..).

  • Manish

    Nice! This was very useful while I was managing WAN network spread across many countries and often getting someone to hook up a PC to get console access can itself be a task. This is very easy but handy.