How To Build A ProxyHam Despite A Cancelled DEFCON Talk

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A few days ago, [Ben Caudill] of Rhino Security was scheduled to give a talk at DEFCON. His project, ProxyHam, is designed for those seeking complete anonymity online. Because IP addresses can be tied to physical locations, any online activities can be tracked by oppressive regimes and three letter government agencies. Sometimes, this means doors are breached, and “seditious” journalists and activists are taken into custody.

With the ProxyHam, the link between IP addresses and physical locations is severed. ProxyHam uses a 900MHz radio link to bridge a WiFi network over miles. By hiding a ProxyHam base station in a space with public WiFi, anyone can have complete anonymity online; if the government comes to take you down, they’ll first have to stop at the local library, Starbucks, or wherever else has free WiFi.

[Ben Caudill] will not be giving a talk at DEFCON. It wasn’t the choice of DEFCON organizers to cancel the talk, and it wasn’t his employers – [Ben] founded and is principal consultant at Rhino Security. The talk has been killed, and no one knows why. Speculation ranges from National Security Letters to government gag orders to a far more pedestrian explanations like, “it doesn’t work as well as intended.” Nevertheless, the details of why the ProxyHam talk was cancelled will never be known. That doesn’t mean this knowledge is lost – you can build a ProxyHam with equipment purchased from Amazon, Newegg, or any one of a number of online retailers.

How To Build A ProxyHam

Image from the original Wired Announcement

In the Wired article trumpeting the ProxyHam to the world. [Ben Caudill] is shown with a laptop wired to a small box with a rather large yagi antenna. This antenna is pointed well above the horizon, indicating the device is not being used, but that’s completely besides the point. The ProxyHam box contains something with an RJ45 connector on one end, and two RF connectors on the other. A quick perusal of Newegg lands on this. a radio base station designed to bridge networks via 900MHz radio. You’ll need to buy two of those to replicate the ProxyHam.

The Wired article describes the ProxyHam further: “…a Raspberry Pi computer connected to a Wi-Fi card and a small 900 megaherz antenna…” Newegg also stocks Raspberry Pis. antennas. and WiFi adapters. You might want to pick up a few SD cards too.

900MHz router seen in the original promo image

To set up the ‘throwaway’ part of the ProxyHam, you’ll need to first connect to the desired WiFi network, then bridge the WiFi and wired connections. Bridging networks with the Raspberry Pi is left as an exercise for the reader with sufficient Google-fu. Of course the 900MHz base station must also be configured, but according to the user guides on the Ubiquiti product page  it’s not much

harder than configuring a WiFi router. Set the radio to ‘bridge’ mode.

From there, it’s a simple matter of connecting a large yagi antenna to the ‘mobile’ part of the ProxyHam. Here’s how you build one. Configure the base station, and plug an Ethernet cable into a laptop. Congratulations, you’ve just replicated a talk at DEFCON by buying stuff from Newegg.

That’s how you build a ProxyHam. That’s also how to violate the FCC Part 97 prohibition against encryption – you can not use SSH or HTTPS over amateur radio. It’s also how you can be charged with the Computer Fraud & Abuse Act; connecting to a library’s WiFi from miles away is most certainly, “exceeding authorized access.”

Do not attempt this build. It’s illegal, it’s dumb, and the 900MHz band is flooded anyway. Also, if your plan for anonymity online revolves around stealing WiFi from Starbucks, why not just steal Starbucks WiFi from the McDonald’s across the street?

Let’s Speculate Why The ProxyHam Talk Was Cancelled

It’s July. In a few weeks, the BlackHat security conference will commence in Las Vegas. A week after that, DEFCON will begin. This is the prime time for ‘security experts’ to sell themselves, tip off some tech reporters, exploit the Arab Spring, and make a name for themselves. It happens every single year.

The idea the ProxyHam was cancelled because of a National Security Letter is beyond absurd. This build uses off the shelf components in the manner they were designed. It is a violation of the Computer Fraud & Abuse Act, and using encryption over radio violates FCC regulations. That’s illegal, it will get you a few federal charges, but so will blowing up a mailbox with some firecrackers.

If you believe the FBI and other malevolent government forces are incompetent enough to take action against [Ben Caudill] and the ProxyHam, you need not worry about government surveillance.  What you’re seeing is just the annual network security circus and it’s nothing but a show.

The ProxyHam is this year’s BlackHat and DEFCON pre-game. A marginally interesting security exploit is served up to the tech media and devoured.  This becomes a bullet point on the researcher’s CV, and if the cards land right, they’re able to charge more per hour. There is an incentive for researchers to have the most newsworthy talk at DEFCON, which means some speakers aren’t playing the security game, they’re playing the PR game.

In all likelihood, [Ben Caudill] only figured out a way to guarantee he has the most talked-about researcher at DEFCON. All you need to do is cancel the talk and allow tech journos to speculate about National Security Letters and objections to the publication of ProxyHam from the highest echelons of government.

If you think about it, it’s actually somewhat impressive. [Ben Caudill] used some routers and a Raspberry Pi to hack the media. If that doesn’t deserve respect, nothing does.


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