In part three of my series, “Technical Notes that Will Most Likely Be of No Interest to Anyone Except Myself,” I discuss how to connect a Gateway Solo 2500 laptop (a ten year old Celeron 333 with no hard drive or ethernet port) to a server running CentOS through a serial interface. Try to contain your excitement.

First, you need to setup the serial console on the CentOS box (basically the same as RHEL or RedHat). There’s a nice tutorial online, the gist of which is:

1. Check serial ports:

[root@navi root]# dmesg | grep tty
ttyS0 at 0×03f8 (irq = 4) is a 16550A
ttyS1 at 0×02f8 (irq = 3) is a 16550A

[root@navi root]# setserial -g /dev/ttyS[01]
/dev/ttyS0, UART: 16550A, Port: 0×03f8, IRQ: 4
/dev/ttyS1, UART: 16550A, Port: 0×02f8, IRQ: 3

2. Configure agetty in /etc/inittab:

# Run agetty on COM1/ttyS0 and COM2/ttyS1
s0:2345:respawn:/sbin/agetty -L -f /etc/issueserial 9600 ttyS0 vt100
s1:2345:respawn:/sbin/agetty -L -f /etc/issueserial 38400 ttyS1 vt100
#s1:2345:respawn:/sbin/agetty -L -i 38400 ttyS1 vt100

3. Create the /etc/issueserial file to be used by agetty (more info):

Welcome to \n.\o
Connected on \l at \b bps

4. Reload inittab with the following command:

[root@navi root]# init q

5. Check to make sure agetty is running. You should see two agetty processes running, one on ttyS0 and one on ttyS1, with the command:

[root@navi root]# ps -ef | grep agetty

6. Finally, if you want to allow root to login through the serial console, you need to modify /etc/securetty to include the serial devices after the “console” line:

ttyS0
ttyS1

That takes care of setting up the CentOS server to allow serial console logins. Now we need to setup the laptop.

The Gateway Solo 2500 was given to me by a friend, so I can’t really complain about its specs:

• 333 MHz Celeron
• 18-bit color 800×600 screen (important to note later on)
• NM2160, 2 MB video card
• 96 MB RAM
• No hard drive (it used to have a 4GB HDD, but that died, and I have no replacement)

Given these specs, I decided to use DSL (Damn Small Linux), since it can run off a CD and is very lightweight. Because the native screen specs are a bit unconventional, you can’t just simply boot up DSL, otherwise you’ll get a faded green screen with blurry, illegible text. Instead, at the boot screen you need to set the correct video mode with:

> dsl 2 vga=788

Once you’re at the shell prompt, run microcom to connect to the server (more info):

root@tty1[/]# microcom -D/dev/ttyS0

If all is well, you should get a login prompt for your server. We’re now able to use a ten year old laptop with no hard drive or ethernet port to manage a CentOS server. (This is the part where you say, “ooh! aah!”)