Enex: Filtering effective, negligible impact

Enex: Filtering effective, negligible impact

Summary: Communications Minister Stephen Conroy today released the highly anticipated results of a test of ISP-based filtering technology, which appeared to show the technology was effective and delivered only negligible speed impact to users, within the parameters set by the communications regulator.


Communications Minister Stephen Conroy today released the highly anticipated results of a test of ISP-based filtering technology, which appeared to show the technology was effective and delivered only negligible speed impact to users, within the parameters set by the communications regulator.

Conroy grimace

Stephen Conroy's ISP filter works
(Credit: Liam Tung/ZDNet.com.au)

"Testing revealed that the three ISPs filtering only the [Australian Communications and Media Authority (ACMA)] blacklist had no noticeable performance degradation that could be attributed to the filter itself ... All participants in the pilot were successful in blocking 100 per cent of the ACMA blacklist. This was a requirement of the pilot," the Enex report stated.

The tests, conducted by Enex Testlabs along with nine ISP participants, broadly revealed that while ACMA's URL blacklist can be perfectly blocked, a more complex list of websites that can block all sites considered harmful to children would also result in significant over-blocking.

"Enex considers it unlikely that any filter vendor would achieve 100 per cent blocking of the URLs inappropriate for children without significant over-blocking of the innocuous URLs because the content on different commercial lists varies and there is a high rate at which new content is created on the internet. Enex has also noted, through previous testing, that the higher the accuracy the higher the over-blocking," Enex reported.

The tests revealed there were also problems with preventing circumvention of a filter that used ACMA's black list.

"A technically competent user could, if they wished, circumvent the filtering technology," said Enex. "Testing showed that the filters used for the ACMA blacklist only were more easily circumvented than other more complex filters used to cover a wider range and volume of material."

However, the report also found that "commercial lists", which go beyond ACMA's 1000-odd long list of banned URLs, would unlikely perfectly filter banned content due to content on those lists changing too frequently.

Attempts to prevent circumvention may also have a greater impact on an ISP's performance, according to the trial's results. While filters could detect an illicit content host's attempts to obfuscate the source of that content, thereby escaping the blacklist filter, Enex found that by doing so an ISP would sacrifice network performance.

Telstra, which had conducted its own filtering trials, said it did not test circumvention because it believed that any technically competent user could find a way around the filter.

Some ISPs, including Telstra and iiNet, have urged the government to release clearer policy around the filter. Issues included whether companies that have been added to the blacklist are not alerted to the fact, while there is no mechanism to redress incorrect inclusions on the list.

More to follow.

Topics: Censorship, Government AU, Telcos

Liam Tung

About Liam Tung

Liam Tung is an Australian business technology journalist living a few too many Swedish miles north of Stockholm for his liking. He gained a bachelors degree in economics and arts (cultural studies) at Sydney's Macquarie University, but hacked (without Norse or malicious code for that matter) his way into a career as an enterprise tech, security and telecommunications journalist with ZDNet Australia. These days Liam is a full time freelance technology journalist who writes for several publications.

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  • Ha

    Take that you haters. Conroy has proved all the doubters wrong. You must all be feeling very silly now.
  • Well done Conroy

    Another waste of money..
  • uhm..

    Obviously need to read the report, but the synopsis above shows that
    a) ACMA blacklist blocking works
    b) Other commerical style filters fail.

    As the ACMA blacklist material is ALREADY being blocked by ISP's, i'm not sure what this trial actually displayed except to confirm the fact that commercial style blocking doesn't work, which is what the industry said all along...
  • Proves nothing new

    From this article, it seems that the trial proved nothing that wasn't known beforehand i.e. that you can filter a blacklist of a thousand addresses with 100% effectiveness and with minimal impact. Honestly, a first year IT student could write a program to do that!

    This test only serves to impress the bureaucratic luddites who can now tick the "effective" box, conveniently overlooking the effectiveness of the blacklisting approach itself when dealing with over 180 million domains (according to verisign) holding billions of websites and registration of some 40 million new domains per year (with 30% of old ones being dropped each year).

    Quite frankly, when you look at the real challenge faced by internet filtering a "pilot" consisting of a 1000 site blacklist is a joke.
  • Wasteful

    A mandatory filtering system that can be easily circumvented. What a waste of money and time.
  • What were the parameters set for negligible performance hits?

    Ok, so we are now officially going to be no better off than we were 20 years ago, when maybe one or two companies had the internet

    I'd like to know what the heck the "regulator's limits were set to" 80% slow down? please get with the times people, this will not work, as is demonstrated with malware sites, phishing scams, spam, you take one down another 50 pop up in its place. someone should throw a shoe at conroy and his cronies
    that would mean on my DSL 2+ connection, i'll be back to what i got when i was on dial up oh say 8 or 9 years ago.
  • Re: Ha

    I don't care for Conroy, as I don't know him. But did you even read and understand the report carefully BEFORE typing on your keyboard?

    * Its approx 80 to 85% effective in blocking inappropriate content. This is ACMA blacklist IN ADDITION TO a content filtering list.

    When they say "successful in blocking 100 per cent of the ACMA blacklist"; they mean it blocks only the sites on the ACMA list. It doesn't NOT block all inappropriate material like people assume...The ACMA list alone is NOT ENOUGH to "protect our children". That's why they supplement it with a Content Filter list.

    * It does NOT block P2P, IRC or any other networking protocols one can use to share nasty material. ie: If one distributes or downloads kiddie porn via those protocols, this filter does NOTHING to stop it.

    *Its trivial to circumvent. ie: By VPN, SSL, TOR, etc.

    *It fails on high capacity sites like Youtube. (It even suggests ISPs will need to spend money on 4x bandwidth capacity to compensate the filter!...Which means your monthly ISP bill goes up to pay for it!)

    Who's silly now?

    It would cost the Australian public less to educate parents and children on web safety, than to introduce a blanket solution like this filter. (As suggested by the Australian child protection group; "Save the Children")

    Why not educate concerned parents in properly setting up their systems so their kids can't mess with it; and getting them to use OpenDNS for blocking inappropriate sites?

    Its reasonably easy to teach, and costs $0. (All one has to do is write up a guide or create a video and distribute it on the web).

    It would be more preferable if we spent that AUD$126 million of taxpayer's money on other things that actually need it over the next four years, than this fundamentally flawed policy.
  • Protection or censorship?

    Welcome to the peoples republic of China? The technical questions are irrelevnat - we know it can be done, BUT how often do we strongly criticise eastern-block countries for limiting internet access to their citizens through just these means? The only difference here is the content of the 'blacklist'... Overblocking is already recognised, and for now the contents 'blocked' are sensible - but what happens when a future government decides it doesn't like to be criticised?
  • Congratulations Australia!

    You are about to join China on the list of champions of free speech and internet access. Internet blacklists? That's so fascist or communist! I thought your country had more liberty than that. My condolences to freedom-loving Australians.
  • Catch the bad guys instead

    This whole filtering thing is back to front. Instead of spending money on the filter, the government should redirect the funds to law enforcement. There is already sufficient legislation to investigate and prosecute those who are engaged in creation, distribution and consumption of child porn. Give the police the funds to get these people behind bars. It'll be a lot more effective than a filter.