Wi-Fi Mini Honeypot
Do you have an old, unused wireless router collecting dust? Have some fun and make a Wi-Fi honeypot with it!
Recently, I've been playing with some new wireless gear. It's nothing special: 200mW Atheros-based transceiver and 18dBi yagi antenna. I'm living in an apartment in a city of about 640,000 people. I've pointed the antenna to a window and passively received about 30 wireless ESSIDs, three of which were unsecured (open) and six secured with WEP (easily crackable). I haven't connected to any of them, of course, but that gave me some ideas.
What if I deployed a wireless access point deliberately open? Some people eventually will connect and try to use it for Internet access—some might be malicious, and some might think that it's a hotspot. And, what if I deployed a similar access point, but secured with easily crackable WEP this time? Well, in my humble opinion, it's not possible to unconsciously crack WEP. If somebody that I don't know connects to this AP, I've just been attacked. All I need to do is to monitor.
That's exactly a wireless honeypot: fake access point, deliberately unsecured or poorly secured and monitored, so you can get as much information about attackers as you want. Such honeypots are especially useful in large networks as early threat indicators, but you also can play with them on your home network, just for fun and research.
You can build a wireless honeypot with old hardware, some spare time and, of course, a Linux-based solution. OpenWrt and DD-WRT are the two most popular Linux-based firmware projects for routers. I use them and some old spare routers in this article to show you how to build three kinds of honeypots: a very basic one that logs only information about packets sent by users into its memory, a little more sophisticated one with USB storage that logs a few more details about malicious clients to the storage, and finally, a solution that redirects HTTP traffic through a proxy that not only can log, but also interfere with communication.
Basic Honeypot with DD-WRT
Building a very basic wireless honeypot shouldn't take you more than an hour or two. Just grab your old router and pick up the firmware. Be sure to look at supported routers for both DD-WRT and OpenWrt. In my case, it came up that the router is supported only by DD-WRT, as it has 32MB of RAM and 4MB of Flash memory. OpenWrt's hardware requirements are a little bigger.
Next, flash your router (that's the risky part). Basically, you need to download the firmware for your machine and upload it to the memory. On some routers, it's as easy as clicking a button on the Web interface. On others, you have to connect through a serial cable, for example. Remember, this step can be dangerous. Make a backup first and be sure to read the instructions carefully on the DD-WRT/OpenWrt sites.
After successfully flashing your router, you should see an enhanced (as compared to the original one) Web interface. Now, set up SSH access and wireless network parameters. If you don't know how, you can find detailed instructions on the DD-WRT home page. As it is going to be a honeypot, I would suggest WEP, which should attract potential attackers. At the same time, it won't be so vulnerable to false positives—people with devices automatically connecting to an open network.
If you can log in as root and see the prompt, you're ready for the next step: enabling system logging. You can do this using the Web interface: Services→Services→System Log and Security→Log Enable (Figure 1).
Figure 1. Enabling System Logging
You also can set a few ESSIDs instead of just one: Wireless→Basic Settings→Virtual Interfaces. After that, your honeypot will be seen as a few networks—at least at first glance. This increases the probability of attacks, especially when there are many other networks in your neighborhood.
Marcin Teodorczyk is a GNU/Linux user with more than 12 years of experience. For the past four years, he's been using Arch Linux exclusively on his personal computers.