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DEF CON 20 - Josh "m0nk" Thomas and Jeff "stoker" Robble - Off-Grid Communications with Android

486 views · Published 30 October 2013 · 50:01 · Indexed 22 September 2026

Channel: DEFCONConference · 2013 · Science & Technology

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Copy of the slides for this talk are here:https://media.defcon.org/dc-20/presentations/m0nk/DEFCON-20-m0nk-Off-Grid-communications-with-Android.pdf
Whitepaper: https://media.defcon.org/dc-20/presentations/m0nk/DEFCON-20-m0nk-Off-Grid-communications-with-Android-WP.pdf

Off-Grid Communications with Android: Meshing the Mobile World
Josh "m0nk" Thomas Breaker of Things @ The MITRE Corporation
Jeff "stoker" Robble MITRE Corporation

Before they were a team, the members of project SPAN thought it was highly limiting to only be able to network smart phones over standard Wi-Fi or with a Cellular infrastructure. Honestly, the SPAN team isn't a big fan of infrastructure-based networks in general. They wanted a headless, dynamic network that allowed for resilient communications when the other infrastructure either wasn't available or when they just didn't feel like using it. They also really liked the idea of a communication system where there was no central router, server or other central point of sniffing of data. With this in mind, they teamed up and created project SPAN (Smart Phone AdHoc Networks). They decided to open source the project and to share not only the code (initial release to coincide with the presentation) but also the whole process and idea with the community at large. The team is annoyed that the current generation smart phone radios have the intrinsic ability to communicate directly with one another, but hardware vendors and mobile OS frameworks don't make it easy to do so. Let us show you how it can be done and the fun that can be had from it.

Join the SPAN team for a deep dive into the Android network stack implementation and its limitations, an analysis of the Wi-Fi chipsets in the current generation of smart phones and a collection of lessons learned when writing your own network routing protocol (or 5 of them). The team will also share a "How To" walkthrough into implementing your own Mesh network and incorporating general "Off Grid" concepts into your next project; this will include securing your mesh from outside parties while tunneling and bridging through the internet. The team will delve into specific Android limitations of Ad-Hoc networking and provide workarounds and bypass mechanisms. Lastly, the team will give an overview of the implementations and network surfaces provided by the new collection of networking alternatives, including NFC and Wi-Fi Direct.

Josh "m0nk" Thomas is a Security researcher, mobile phone geek, mesh networking evangelist and general breaker of things electronic. His past projects have commonly spanned the hardware / software barrier and rarely have a UI. He's spent the past 12 years poking at embedded systems, networks, IP stacks, AI and right-time communication systems. A code monkey at heart, m0nk has spent the last year digging deep into Android and iOS internals, with a major focus on both the network stack implementations and the driver / below driver hardware interfaces. He uses IDA more frequently than Eclipse, really just likes playing with gadgets and wants to make the world a better place. His life dream is to ride a robot unicorn on a moonlit beach.
Twitter: @m0nk_dot

Jeff "stoker" Robble has been writing Java and Android software for quite a while now and he's become bored pushing blinky lights to the screen. He wanted to dig deeper into the internals of network stacks and smart phone handsets and SPAN was the perfect opportunity. At last count, Stoker was seen carrying 14 Android devices in his backpack and was mumbling something about Ice Cream Sandwich and WiFi Direct scalability.

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