FreeBSD Handbook
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2.12 Advanced Installation Guide

Contributed by Valentino Vaschetto.

This section describes how to install FreeBSD in exceptional cases.

2.12.1 Installing FreeBSD on a System without a Monitor or Keyboard

This type of installation is called a “headless install”, because the machine that you are trying to install FreeBSD on either does not have a monitor attached to it, or does not even have a VGA output. How is this possible you ask? Using a serial console. A serial console is basically using another machine to act as the main display and keyboard for a system. To do this, just follow the steps to create installation floppies, explained in Section 2.2.7.

To modify these floppies to boot into a serial console, follow these steps:

Enabling the Boot Floppies to Boot into a Serial Console

If you were to boot into the floppies that you just made, FreeBSD would boot into its normal install mode. We want FreeBSD to boot into a serial console for our install. To do this, you have to mount the kern.flp floppy onto your FreeBSD system using the mount(8) command.
```
# mount /dev/fd0 /mnt
```
Now that you have the floppy mounted, you must change into the /mnt directory:
```
# cd /mnt
```
Here is where you must set the floppy to boot into a serial console. You have to make a file called boot.config containing /boot/loader -h. All this does is pass a flag to the bootloader to boot into a serial console.
```
# echo "/boot/loader -h" > boot.config
```
Now that you have your floppy configured correctly, you must unmount the floppy using the umount(8) command:
```
# cd /
# umount /mnt
```
Now you can remove the floppy from the floppy drive.
Connecting Your Null Modem Cable

You now need to connect a null-modem cable between the two machines. Just connect the cable to the serial ports of the 2 machines. A normal serial cable will not work here, you need a null-modem cable because it has some of the wires inside crossed over.
Booting Up for the Install

It is now time to go ahead and start the install. Put the kern.flp floppy in the floppy drive of the machine you are doing the headless install on, and power on the machine.
Connecting to Your Headless Machine

Now you have to connect to that machine with cu(1):
```
# cu -l /dev/cuaa0
```

That's it! You should now be able to control the headless machine through your cu session. It will ask you to put in the mfsroot.flp, and then it will come up with a selection of what kind of terminal to use. Select the FreeBSD color console and proceed with your install!

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