Build a PS2 Keyboard for use with WatchGuard Firebox devices


So you have an X-series firebox and flashed a new bios to allow serial console access to the system. Then you did something stupid like I have and somehow managed to disable your serial port in bios while replacing the CF card with a larger (4gb) card. You are left with a CF card that has died (or is unusable), the firebox won't talk over serial anymore because it hates you, and you are trying to use a Hard Drive now to replace the unreliable CF card...

Life can be annoying sometimes. For this, we hack stuff. In doing this, life is better! We will destroy a ps2 keyboard and internal firewire “expansion” cable to make this possible. We will gain a new keyboard built just for talking to a firebox. =) This might seem like overkill but hey, we have those “Ill use it someday” parts bins for this exact reason right? (Or at least thats what we tell the SO...)


We want to run pfSense on our nice shiny x550e firebox. However, to get everything up and running we need to get access to the bios. We are going to setup version 2.1.2 of Pfsense. This is the version that has the patch for “HeartBleed” that came out this week (4/12/2014). Yay for security exposure!


To modify a PS2 keyboard for use with a WatchGuard Firebox (x/e series or possibly others). For use with accessing the bios due to the lack of posts for USB or other connections. Attempts to use a USB expansion card on either of the PCIe slots have resulted in failure. Apparently most of the cheap cards require a driver to work correctly and will not allow you to interact with the bios. (Lesson Learned -- Card tested is an I/O CresT PCI-Express USB3.0 controller card, found on amazon SY-PEX20041).


1. You have an xSeries firebox. In this particular case we are using an x550e firebox. Anything from the x550e - x12+e should work here.

2. You have some minor soldering skills.

3. You have a PS2 keyboard you are ok with butchering.

4. You have an “internal firewire” or similar connector that you are ok butchering (this is only for the keyboard to motherboard connector. If you can source an 8-pin connector that will also fit you can use that instead. the pinout is the same). See the below image for an example.

5. You have a pci-e 1x-8x graphics card to display video output from the firebox with.


Image credit:


The keyboard we are using is an old HP PS2 keyboard. It has lived a long life and will be sacrificed for the greater good of making it easier to modify our firebox.

The first order of business is to chop the end of the PS2 keyboard cable off. Just leave yourself enough room to resplice/cut/etc the cable as needed.

We peel back the insulation to find a ~5 wires. The colors are listed below but different keyboards or reversions may use different colors.


Wire colors:





Unshielded (silver/ground)

See image to the right:

Once we have done this, it is time to chop up the firewire connector. The one that we are executing is intended to be used in the back of the pc in one of your expansion slot shields. The connector itself is 10-pin and colored red. It goes to a single firewire connector.


The coloring expressed is as follows.

1. Blue

2. Orange

3. Black

4. Black

5. Green

6. Red

7. Black

8. White

9. XXXX (key pin)

10. Black

See the image for reference.  

Note: The (1) in the top right can be considered “pin 1”.

We have a number of pins that we will not need to use. In this particular case we are only interested in the following.

1. (Blue)

2. (Orange)

4. (Black)

8. (White)

The rest can be considered extraneous.

Solder/connect the wires as follows:

Keyboard Wire

Firewire connector wire

Firewire Pin Number
















See the image for reference (sorry for the bad picture, I was in a hurry to get this done so there is no shrink-wrap to make it pretty).


You should now have a fully working PS2 keyboard for use with the x550e firebox.

Good Luck!