Category Archives: Ubuntu

Mactel, Ubuntu and Serial Console

I have been using an older HP 6730b for a few years mainly because of the hardware serial port, but it has been getting a bit long in the tooth and it was time to replace it.

I picked up a second hand Macbook pro 13″ with an SSD off a co worker as they were upgrading. I am a reformed windows user that switched to ubuntu about 8 months ago, on both my home and work desktop so I found the move to OSX a frustrating experience.

After some research I found that Ubuntu would actually run on my macbook so I went ahead and installed it. Everything works quite well, but as it does not have a hardware serial port I need to use a usb to serial converter.

I did not know how to get a serial console up and running in linux, until a co worker suggested that I use the screen application. The usb to serial converter does not need a driver to be installed, I just plug it into my macbook and use screen by doing the following:

  • Open a terminal window
  • sudo screen /dev/ttyUSB0

One thing I was stuck on is how to send a break command when a router or switch boots.   To break into rommon mode, as the macbook does not have a break key.], I found that you can use the following key combination:

  • ctrl + a then ctrl + b

You can also avoid having to use the sudo command when running screen by adding the user to the dialout group, giving the user correct permissions to access the console:

  • sudo adduser < username > dialout
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