Tuesday, October 26, 2010

New Wi-Fi Direct Protocol We've Got Some Answers

I've seen a lot of discussion over the new Wi-Fi Direct protocol and it seems like no one can really nail down all the specifics. So I've decided to do a little digging and do my best to answer a few questions that I've seen posted. Some of these answers and more can be found via the Wi-Fi Alliance Frequently Asked Questions page.

Backward Compatibility - One of the most often asked question is will it work with legacy Wi-Fi devices. The answer is yes and no. Legacy devices will be supported for connecting to a new Wi-Fi Direct certified device but your older devices will not support the new protocol to do any routing or directing of network traffic as a Wi-Fi Direct device would.

Will A Software Update Make My Device Wi-Fi Direct? - It is my understanding that only new Wi-Fi Direct certified devices, which there are some already out there, can use the new protocol. So no AFAIK a software update will not work to make your older device into a Wi-Fi Direct device. I believe these are new chips and a new protocol so until I hear otherwise I'll stand by that assumpotion

How many devices can connect? - This is a tough one to answer as it really depends on your devices. A Wi-Fi Direct-certified network can be one-to-one, or one-to-many. The number of devices in a Wi-Fi Direct network is expected to be smaller than the number supported by traditional standalone access points.

Your Router or AP can connect literally hundreds of devices a Wi-Fi Direct network is really only meant to handle a few devices at one time. Some devices will limit the number of connections to multiple other devices as this is an optional feature that will not be supported in all Wi-Fi Direct-certified devices; some devices will only make 1:1 connections, some will allow several devices to be connected at once.

How far will a Wi-Fi Direct connection travel? - Just like any standard Wi-Fi device in use now a Wi-Fi Direct devices will have a variable range. Things like dense walls, interference from other devices ect will have an undoubtedly have an affect on your range. The max advertised distance is 200m but that's not likely to happen. So I'd say like most standard Wi-Fi devices your range should be expected to be wide enough to reach throughout your entire house.

How About Security? Is Wi-Fi Direct Secure? - I'm on the fence about this one. Wi-Fi Direct uses forced WPA2 authentication and encryption which can not be disabled. That's all great and all but that doesn't help once a device is connected. P2P connections are inherently insecure and without a firewall or added security allowing device like cameras, smartphones and god knows what to become a node for network you might be asking for trouble. Of course its assumed that you are only going to be making connections with 'trusted' sources, but is that really likely?

Part of the problem I see is the Wi-Fi Direct program use a service discovery association which relies on a simple handshake protocol for a connection. Basically any one can see your Wi-Fi Direct device that is 'discoverable' and can ask you for a connection or they can be 'discoverable' themselves and allow you a connection. This opens a ton of doors to several types of attacks namely "man in the middle attacks". I also see the potential for brute force attacks that can result in a device being forced to accept a connection. WPA has already been cracked and hackers can already insert malicious code into transmissions so I really question the security here.

The Wi-Fi Alliance says Wi-Fi Direct defines a new pre-association discovery method, which limits the amount of information given about device services prior to association (and before having an IP address). From my understanding this should provide some added security as an attacker won't know much about the device they are connecting to thus limiting there attack. But again I see many areas of concern!

If I make a Wi-Fi Direct connection will others see the contents of my device? - This is one major area of concern! If you've ever been to an internet cafe and browsed any of the other connection you know many times users have file and network sharing on. Essentially providing an open door to shared files on their PCs. Apparently this won't be an issues as nothing is shared without your permission. The content available over a Wi-Fi Direct group connection is driven by the applications you are using. While there may be applications which allow an authorized use to “browse” the content on your device, most applications will have a specific focus (e.g., sharing a game application or transferring photos).

Again, this is another issue that is very much in a grey area so users will want to make sure their Apps aren't sharing more than they want them to. I can already see this as being potentially exploited so make sure you are safe!

My Conclusion:

For now it seems as though there are a ton more questions than there are answers. I've seen numerous discussions on several sites as to how and why you'd implement Wi-Fi Direct. To be honest for an average user that already has a home wireless network you aren't going to gain much by upgrading to new devices.

One area that would be helpful that I didn't touch on is the use of a Wi-Fi Direct device as an AP to share a network connection. This could potentially be useful for users that need to expand their coverage throughout there house or for families that use multiple devices connected to a single wireless broadband connection.

The tone of my article might be a bit negative and admittedly I'd say I don't like the idea of my 'dumb' devices potentially being nodes for everyone else to connect to. I'll also say I'm not big on all my devices being wired into each other. But I do see some potential upsides here.

If you want more details checkout the Wi-Fi Alliance Wi-Fi Direct Page:

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