Tuesday, June 21, 2011

WiFi Sniper Rifle

I'm working an insane amount. Between the hospital and school, it doesn't leave much time. I stuff that time with the consulting work, and efforts on a new project to make a fair amount of money.

This post is about none of that.

One of my classes last semester was Wireless Network Security. It seemed to me that like many security problems, this was one of access. To top it off, because many people (and still some organizations) use shoddy security, if you can just get access, you are on the network. I've sat in a couple of dining rooms and offices showing clients how quickly their network can be compromised by not using their security tools correctly.

I'm also getting ready to go on vacation in the wilds of Canada. I'll be honest, I like my internet to be readily available, wherever I go. The last time I was there, we had some issues with signal and antenna aiming. I've been thinking about that problem ever since.

I had some parts lying around the house. Specifically for this project I used only a couple of real parts:
1x 802.11 2.4GHz "25dBi" antenna (Supposedly it works on 5GHz as well, I haven't tried)
1x 802.11n MIMO USB adapter, with two removable antennas
1x AR-15 Lower Receiver with handle (Airsoft Surplus, no modifications needed)
1x Removable stock
1x Cheap Bushnell Scope w/mounts
1x Short length of P-rail to mount the scope

I also used some PVC piping (1 inch, I think) to act as a pillar for the antenna, lower receiver and scope to attach to. I made a small acrylic block and secured it to the PVC pipe as a connection point between the PVC and the lower receiver. Various screws, nuts and some scrap wood were used (The scrap wood was planed to fit in the butt of the PVC, to further secure the PVC to the lower receiver. Another plug was fit to secure the pistol grip to the lower receiver).

I sent a picture to a friend of mine. I think I need to do this with all of my kit-bashes from now on. In the past he's typically been working next to me, when I do these things. He frequently says things like "Are you sure you want to....", or "Hey man, that's not real smart....", or "Is something burning?"
In short, he's the safety cut-out for many of my projects (Despite the fact that he literally has an entire self-inflicted injury category named after him).

His first reaction "Dude! (He's 37 or something) Dude! Is that a railgun?"

So I disappointed my best friend, but again, he probably saved me some grief by showing me a big problem.

This thing looks just like a firearm. More to the point, it's a scary firearm that will make everyone twitch if they see it. Not exactly the kind of thing you want to hang out with on a hill, and point at random dwellings to get an idea of its range.

Now, as an aiming device, this thing is going to be great. I'll be able to visualize my target antenna, and then slowly move the system around to get the best signal. However, I already recognize the difficulty of typing while shouldering the "rifle".

To combat that (and the scary pointing issue), I'm working on a tripod mount for the antenna and PVC assembly. Once the signal is established, I can disassemble the stock and lower receiver around the antenna/PVC assembly, which are secured using a stable tripod.

This is going to work really well in the Wilds of Canada (It sounds cooler when I capitalize it), and at home, I probably won't need the extreme range features of the whole build. I may look at a method of just securing a hand grip directly to the PVC. Then it's going to look like I'm aiming a giant linear antenna, instead of a railgun.

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