Access a Cisco Switch via USB Console

It may be that you want to use a USB cable, or it may be that just like me you forgot your USB to serial adapter, and now your faced with connecting to a Cisco switch with a USB cable rather than the serial cable on OSX.

Well how do we go about this, with Windows we could simply look up the port number in device manager, with OS X they do not use this reference, instead referring to the device as a TTY USB modem.

First we need to look up the device, which is contained with other devices in the folder /dev/, we also want to limit it to devices of the USB type so we are going to limit the command to that. Open terminal and type the following command;

ls -ltr /dev/*usb*

This will list all devices in the /dev/ directory (the devices directory) where it contains the key phrase usb within it, with all information, in a list with the most recently modified device (and therefore most likely the device we are looking for)

Your device will show up as something such as

tty.usbmodem.12a1

Now we have the path to the device, we need to open a console using it. In OS X the console utility screen is built in, so lets open it utilising this utility and a baud rate of 9600 which most devices will happily handle. To do this type;

screen /dev/tty.usbmodem.12a1 9600

What this command is stating is open screen on device /dev/tty/usbmodem.12a1 utilising a 9600 baud rate, no settings for stop bits etc are input, you can also utilise other baud rates if needed.

Your terminal will now connect to the console of the Cisco device, this should also however work for any other devices that utilises a USB chipset to communicate via serial emulation.

Justin

Written By Justin

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