Kyle Brandt

Original computing and productivity articles by a Linux administrator

How-To: Connecting to a CISCO Router Console Port with USB and Linux

I was lucky enough to be loaned a couple of CISCO 1720 routers by my office today. Connecting to them was pretty straight forward.

What you will need:

1. A roll-over cable (aka Cisco Console Cable). These are usually RJ-45 on the router side and serial on the PC side.

2. If your computer doesn’t have a serial port (like mine) you can get a 9-pin D-sub serial to USB cable. I got the Gigaware cable from RadioShack for thirty dollars.

Get Connected:

The following worked for me with Hardy Heron installed on my MSI Wind.

1. Connect all the cables: USB — > Serial –> Crossover –> Console Port
2. Download and install Minicom: sudo apt-get install minicom
3. Make sure that the USB to serial cable is recognized. lsusb should list something like Bus 001 Device 002: ID 05ad:0fba Y.C. Cable U.S.A., Inc.
4. Type ls /dev/tty* to make sure /dev/ttyUSB0 or something similar is listed.

Update: In my search to reset the password to the router, I needed to send a break to the console. I was finally able to do this using GNU screen. Screen is easier than minicom, all you need to do is type screen /dev/ttyUSB0 instead of the remaining steps five through eight. I was then able to send my break using [meta-command]-B or [meta-command]-b (Not sure which it was).

5. Start minicom with minicom and hit CTRL-A and then O to open the options. (All commands in minicom start with CTRL-A, like GNU Screen).
6. Enter A to change the serial device setting to /dev/ttyUSB0 or whatever you found in step 4.
7. Select “Save setup as dfl”
8. Hit CTRL-A X to exit and then restart minicom, the port should be displayed as /dev/ttyUSB0
9. When it restarted all I had to do was hit enter to get the prompt of my CISCO 1720

with 4 comments

August 11th, 2008 at 3:29 pm

Posted in Linux, Networking

Tagged with ,

4 Responses to 'How-To: Connecting to a CISCO Router Console Port with USB and Linux'

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  1. Hi Kyle, I installed everything as you suggested on my Ubuntu Gutsy, but I am not getting the console prompt on minicom when I hit enter (as per the last step). Anything you could suggest?

    Sudipta Chatterjee

    18 Sep 08 at 11:52 pm

  2. Oh never mind the last comment — screen /dev/ttyUSB0 worked and I have the prompt! Thanks a ton for posting this!! :)

    Sudipta Chatterjee

    18 Sep 08 at 11:54 pm

  3. Thanks, great help

    luquiton

    27 Mar 09 at 6:40 am

  4. Thanks a lot, a great help!

    berry

    5 Apr 09 at 6:30 pm

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