Enable Serial Console

Mon, Jun 1, 2009

Linux

This tutorial will show you how to set up a serial console on a Linux system, and connect to it via a null modem cable. This is quite useful as it allows you to easily get a console on the system if there are any problems with it and you cannot access it via ssh

Check that you have a serial port and it is enabled in your bios

dmesg | grep tty

root@duffys-place:~# dmesg | grep tty
serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
00:09: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

Configuring Lilo

  1. open up /etc/lilo.conf
    nano /etc/lilo.conf
  2. Find the the serial line and change it to the following:
    serial=0,38400n8
  3. Now edit your kernel settings so they include the line
    append="console=ttyS0,38400n8"

    It should look something like this

    default=Linux
    image=/vmlinuz
            label=Linux
            append = "console=ttyS0,38400n8"
            initrd=/initrd.img
  4. Run /sbin/lilo to apply the changes

Enable Logins

  1. Open up /etc/inittab
    nano /etc/inittab

    and add the following line

    T0:2345:respawn:/sbin/getty -L ttyS0 38400 vt100

Testing It

  1. Plug one end of your null modem cable into your server and the other into your computer
  2. Open your terminal client i used putty hyperterminal works fine too
  3. Use the following settings:
    Port: COM1 or COM2(what ever your serial port is)
    Bits per second: 38400
    Data bits: 8
    Parity: None
    Stop bits: 1
    Flow control: None
  4. You should be able to see your console. If you have any issues feel free to leave a comment
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