Sysadmins slam ACMA web filtering study

Stephen Withers
Thursday, 31 July 2008 15:31

Business IT - Networking

The System Administrators Guild of Australia has criticised the Australian Communications and Media Authority's report on ISP-level content filtering, questioning its relevance to real-world conditions. A major objection is that the ACMA tests did not align with the actual bandwidth expected and demanded by today's Internet users.

SAGE-AU member Mark Newton questioned the validity of the baseline performance test conducted by ACMA.

"The baseline performance test featured 30 users on a gigabit switch saturating the test web server at 425 megabits per second (page 30), and stated that that would be equivalent to around 20,000 end users each on 1.5 Mbps connections (page 31)," said Newton. "However, 425 Mbps divided among 20,000 end users actually gives each user 21,250 bits per second, around half of what can be achieved with a dial-up modem."

"While it's probably true to say that filtering software doesn't present noticeable performance degradation when you've already artificially constrained the offered traffic rate to below dial-up speeds, it's difficult to see the relevance of that conclusion in a world where the Minister wants everyone in Australia to connect over 500 times faster," he added.

The Guild also expressed concerns about the false positives encountered during the ACMA test. The most accurate filter tested incorrectly blocked three percent of requests, but when scaled up to the traffic volumes of a medium to large ISP this would mean over 3000 requests would be blocked every second.

This would presumably generate a huge number of helpdesk requests, driving up the cost of Internet access and therefore increasing the digital divide.

What are the other limitations of filtering in SAGE-AU's view? Please read on.