Posts Tagged ‘algorithms’

Introducing Anonymity to Youtube

The video sharing giant, YouTube has introduced a long needed feature to protect peoples anonymity – the ability to blur peoples faces.  For many years activists and protestors living in police states and under dictators have used social media sites to inform the world of events in their countries.  Often with communications locked down and extensive surveillance in place these sites are the only ways that people can communicate with the outside world.  Unfortunately in countries like Syria, Iran and many of the ex-Russian states the authorities use these videos for their own security requirements.

Just think about it – these protest videos will commonly involve activists speaking out against regimes, close pictures and video streams of protests – all identifying leading activists and protesters.  All the regimes have to do is identify them and go and pick them up.  They also use them for real time security operations, videos are often uploaded live during meetings and protests.  Security services can use them to quickly identify locations and send people in to disrupt or arrest individuals involved.

There are no specific figures on how many people have been arrested across the world because of these videos, but it is certainly in the thousands judging on the number of stories that circulate.  Giving users the ability to quickly blur faces and other recognisable features in a video will go a long way to protecting the safety of activists in countries like Iran.  It of course doesn’t offer the true panacea of online anonymity that sites like this aspire to – http://www.onlineanonymity.org/  but it offers an important level of protection.  It also raises awareness of the dangers that posting these videos online can cause.  Many videos are uploaded by bystanders or angry young people who perhaps don’t consider the consequences of identifying activists on the front line.

There are other issues with uploading and identifying individuals online, there are definitely other dangers too.  Many people fail to consider that their IP address is logged, by many different servers while they are online.  Records exists in ISPs and on the web servers you connect to.  The only way to protect this is to obscure your real IP address and encrypt your connection.   Ironically although not advocated as a security precaution – this video about watching the BBC outside the UK  http://www.iplayerabroad.com/, demonstrates one method of uploading videos anonymously.

The technology is not quite perfect and we are unsure behind the effectiveness of the algorithm that detects and blurs the faces.  This is not a selective technology either at the moment with YouTube only offering the facility to blur all faces (not select which to blur and which to leave). Whatever it’s initial shortcomings though, it’s certainly an important step in offering some level of privacy online and hopefully we’ll see similar measures being implemented at other video and photo sharing sites shortly.

 

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The Nagle Algorithm

On many networks you’ll find lots of little packets of data flying all over the place.  These small packets are commonly known as tinygrams and on most standard Local area networks they are not really an issue.  This is basically because your average local network is not really congested and this data doesn’t cause much of an issue.  However when you are using a slower Wide Area Network (WAN) then they become a very big problem.  RFC was released containing an elegant solution to this problem and it’s called Nagle’s algorithm.

This algorithm states that when a TCP connection is still waiting for an acknowledgement, then no small segments can be sent until the ack is received.  Instead then small parcels of data are collected by TCP and sent in a single segment when the acknowledgement is received.   The real advantage of this algorithm is that it is self clocking.  The faster the ACKs are received then the quicker the data is sent out.  This can help greatly on a slower WAN as it will significantly reduce the number of these tinygrams which are sent across the network.

It has been so successful that it is currently enabled on all Microsoft Operating systems.  However some gamers insist that it can affect performance. Of course when that single delay on a click, command can deal your character a premature death – this stuff is important. Although if you’re playing a game based across the Atlantic then you may be better advised to invest in a US IP address  instead and not mess around with your registry.  It’s the safest option if you can afford it and you can find more information on this page – http://www.proxyusa.com/usvpn

If you do want to turn it off them you’ll need to modify the following registry key –

HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters\\Interfaces

Under here you’ll see your network interfaces listed. Pick the one which you want to modify (i.e. your internet facing card) and then you need to create a couple of new entries. You need two new Dwords – first one called TcpAckFrequency and the second one TCPNoDelay (both case sensitive). Then set the values of both these settings to Value Data = 1, that’s all their is to it. You can then reboot your machine and the Nagle Algorithm settings will not apply to that interface.

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