[Commotion-discuss] Ad Hoc WiFi MESH networks

[Josh King]

Hi Sritam,

Your understanding is basically correct, the Commotion firmware is installed on certain routers
which then form a mesh network over wifi. Other, non-mesh devices can then connect to the network
via a conventional wireless access point or via ethernet, at which point they are able to connect to
other services and devices that are connected to the network.

There are innumerable potential security challenges in working with multi-hop wireless networks. If
we're talking about just the challenges in adding new routers to an existing network, they can vary
widely depending on the management model of the network. They include but are not limited to:

* Authenticating a new router to the network. If you want to have a network that only allows
authorized routers to join, then you need a way of making sure that only certain routers are
authorized. This could potentially be accomplished with a PKI, but then requires that authentication
is centralized and also requires managing your own certificate authority (complicated). Commotion
requires by default that every router has a shared WPA key and optionally that it has a separate
shared key for signing management traffic. This has low overhead but requires a shared secret
between every node in the network.
* Being able to identify bad actor nodes in the network. Right now it is not easy to determine that
a particular router is misbehaving, and to drop them from the network. Ideally the authentication
system would allow for being able to drop routers from the network or mitigate their bad behavior
without rekeying the whole network.
* Protecting end-to-end network traffic. Traffic in Commotion is encrypted over each hop but is not
encrypted end-to-end. This means a bad actor node could potentially eavesdrop on user traffic.

These problems and others are made more complicated by some pretty significant constraints:
* Commotion at least has a goal of not relying on any centralized management platform. Therefore,
any fundamental security measure must at least be able to operate without centralized systems.
Commotion also must be capable of operating offline without any connection to the wider internet.
* Routers are bad at cryptography. They have extremely limited storage and processing power, and
little entropy. They also have fairly inaccurate clocks.
* Wifi is vulnerable to interference and jamming, either intentional or unintentional. There's
little that we can do about that.
* Due to the limited resources on routers, any solution must be extremely small (as far as code
size), efficient, and use as little airtime on the network as possible.

The stuff I'm working on will introduce opportunistic end-to-end encryption to much of the network
at very low overhead, while also pushing as much of the crypto to the edges of the network as
possible. But that's only a partial solution to some of these issues. So if you have any thoughts on
stuff you'd like to work on, I'd be interested to hear it! I hope this was helpful.

On Tue, 2017-03-14 at 13:58 +0000, Paltasingh, S. wrote:
> Dear Sir,
> 
> My master's thesis project is: Secure Commissioning (Forming/Joining) In Ad Hoc WiFi MESH
> networks. 
> 
> I read the documentation of commotion and this is what my understanding is:
> 1. Commotion software platform supports formation of Ad Hoc WiFi MESH network but confined to only
> routers.
> 2. In other words Commotion software platform  enables formation of Ad Hoc WiFi MESH network of
> routers.
> 3. Laptops (phones, tablets) will behave as legacy WiFi nodes and will connect to one of the
> commotion routers (in a star topology) which is having MESH connection with other commotion
> routers. The actual MESH is formed between the routers running the commotion software.
> 
> Is my understanding correct as per the documentation provided by commotion wireless project ??
> 
> If Yes, then is there any MESH security challenges that needs to be incorporated at the time of
> joining of a new router (running commotion firmware) to the existing MESH network. I can work on
> those security challenges and contribute to the commotion community as my master's thesis work is
> also related to finding solutions to those kind of security challenges.
> 
> Looking forward to your valuable comments and suggestions.
> 
> Thanks and Regards,
> Sritam Paltasingh.
> _______________________________________________
> Commotion-discuss mailing list
> Commotion-discuss at lists.chambana.net
> https://lists.chambana.net/mailman/listinfo/commotion-discuss
-- 
Josh King
PGP Fingerprint: 8269 ED6F EA3B 7D78 F074 1E99 2FDA 4DA1 69AE 4999
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