Linux - connect to a serial port with screen
There are a bunch of programs out there, that can get you connected to a serial port of a switch, but using screen
was the best and easiest solution I've found. Works perfectly in the CLI, can be run in the background, and easy to set up - if it is not already installed.
It worked with various combinations of serial-to-usb-cables, Cisco switches, and Linux machines. Let us start with the command itself:
-
sudo screen /dev/ttyUSB0 9600
-
sudo screen
- runscreen
as sudo -
/dev/ttyUSB0
- the tty number of the usb cable / adapter -
9600
- the speed of the serial connection
-
You can kill the session with CTRL
+ a
, then k
, and confirm it with y
.
Finding the device / the tty number
Find the tty number while you are already connected:
sudo dmesg | grep tty
Output:
kuser@pleasejustwork:~$ sudo dmesg | grep tty [ 0.134050] printk: console [tty0] enabled [1724834.635665] usb 3-1: FTDI USB Serial Device converter now attached to ttyUSB0
Shows the device while plugging it in:
sudo dmesg -wH | grep tty
Output:
kuser@pleasejustwork:~$ sudo dmesg -wH | grep tty [sudo] password for kuser: [ +0,000022] printk: console [tty0] enabled [ +0,001283] usb 3-1: FTDI USB Serial Device converter now attached to ttyUSB0
This is helpful if you are connected to multiple devices.
Finding the correct speed
I haven't had to change this yet, but just in case:
sudo stty -F /dev/ttyUSB0
Output:
kuser@pleasejustwork:~$ sudo stty -F /dev/ttyUSB0 speed 9600 baud; line = 0; -brkint -imaxbel
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