Internet filtering ineffective in fight against terror

Cross "fighting terrorism" off the list of reasons Senator Stephen Conroy wants to introduce mandatory ISP-level Internet Filtering.

A new report penned by Tim Stevens and Dr Peter Neumann for the International Centre for the Study of Radicalisation and Political Violence (ICSR) assesses the pros and cons of various types of Internet Filtering and finds them ineffective in the fight against terror.

"Most governments have focused on technical solutions, believing that removing or blocking radicalising material on the internet will solve the problem," the report states.

"Yet, this report shows that any strategy that relies on reducing the availability of content alone is bound to be crude, expensive and counterproductive."

The report went into some detail around the ineffective nature of most types of Internet Filtering.

IP filtering, in which the IP address of a questionable site is blocked, suffers from misfiring, the report said.

"Problems with this method of filtering arise because some web hosts - each with a single IP address - provide a variety of services or host many websites with different domain names, which means that all these acceptable services and sites will be blocked as well. While cheap and easy to implement, its propensity for 'over-blocking' makes IP filtering a very crude method of interdicting banned material."

Content filtering, which interrogates every Internet Protocol packet for content that matches blacklisted keywords, is also criticised.

"This is an expensive means of filtering, because it requires whole data streams to be reassembled when keywords are split between different packets. Furthermore, because many sites that contain blacklisted keywords may not be extremist at all - some, in fact, may be dedicated to countering extremist propaganda - governments would also have to maintain (and constantly update) a 'white list' of permitted sites against which any request for information would be compared."

And while content filtering might be acceptable in communist China, the report doubts whether it would be acceptable in "most liberal democracies."

"The financial costs may be considered prohibitive in different national contexts. At a philosophical level, the idea that access to information is decided purely on the basis of automated judgement calls determined by software designers would probably be seen as unacceptable in most liberal democracies."

Proxy filtering, in which ISP-hosted local copies of web sites are used to allow or disallow requests, was also judged as being too expensive and inefficient.

"If the system were to be rolled out across entire networks and internet service providers failed to make substantial investments in the required hardware, it could slow down internet traffic substantially."

The ICSR had better things to say about hybrid IP and proxy filtering, a system used in Britain which overcomes the expense of proxy filtering and over-blocking of IP filtering.

"In the first instance, this system checks against a list of IP addresses, but does not block them immediately. Instead, all requests for 'problematic' IP addresses are channelled to a proxy server which inspects them for individual web pages and blocks them if required. The initial layer makes it possible for the vast majority of internet traffic to proceed without a full inspection, thus reducing the expense of straight proxy filtering."

But while hybrid filters provide the right trade-off between cost and accuracy, the report's authors said the method still "fails to capture dynamic content such as chat and instant messaging and relies on blacklists of banned web pages," which has some political implications.

The ICSR instead recommends the selective use of takedown notices in conjunction with prosecutions which clearly "signal that individuals engaged in online extremism are not beyond the law."

Australian law already accommodates this strategy.

"Any strategy that hopes to counter online radicalisation must aim to create an environment in which the production and consumption of such materials become not just more difficult in a technical sense but unacceptable as well as less desirable."

The report resonates with Australian academic John Selby, lecturer in business law at Macquarie University.

"What is needed in Australia is a more nuanced approach to this issue of the regulation of 'undesirable content' on the Internet," he told iTnews.

"Arguably, there is no silver bullet solution that we can just build and then forget because it will have solved this issue forever.

"As a nation, we should research and carefully evaluate the political, legal, social, economic and technical costs and benefits of a variety of strategies, including the current proposal from Senator Conroy, to determine which would be the most effective before we dedicate too many resources to any one particular strategy. "

The ISCR is run in partnership by Kings College in London, the University of Pennsylvania, Israel's Interdisciplinary Centre Herzliya and the regional centre for conflict prevention Amman.