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    Console Serial Connections To Cisco Devices On Nix

    Posted on 2 mins

    Cisco Linux Console

    Table of Contents

    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.

    Detach from a session so it can be restored later.

    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.