Summary#

This is just some notes for connecting to the console port on Linux. This is a running post where I will be adding new methods for connecting to the console port on Cisco devices or any device that supports a serial console.

Finding The Console Port#

Finding the console port is pretty easy. But, I’m going to list it here just for reference.

sudo dmesg | grep -i tty

The output should look something like this.

[    0.168530] printk: console [tty0] enabled
[    0.790340] 0000:00:16.3: ttyS4 at I/O 0x3060 (irq = 19, base_baud = 115200) is a 16550A
[   14.803912] usb 1-2: pl2303 converter now attached to ttyUSB0
[   34.143924] Bluetooth: RFCOMM TTY layer initialized

Connecting With screen(1)#

Going to go through some methods for connecting, disconnecting, and detaching while using the screen(1) command.

Connect just using the TTY device.

sudo screen <tty device>

In this example. It would be the following command based on the output from dmesg(1). This will connect the screen console to ttyUSB0.

sudo screen /dev/ttyUSB0

Terminate the session while connected.

  • Ctrl + A and then K.

Detach from a session so it can be restored later.

  • Ctrl + A and then D.

To look for detached sessions. The following command can be used.

sudo screen -ls

Below is the ouput for this command. It shows that there is a screen(1) session that’s detached.

There is a screen on:
	6600.pts-2.rubik	(12/09/2022 07:59:27 PM)	(Detached)
1 Socket in /run/screen/S-root.

To attach back to the screen name. The following command can be used. One thing to think about. If there are multiple sessions open. The -x flag needs to have a unique value.

sudo screen -x 6600

These are just some notes for using screen(1) to connect to serial interfaces.