It would be technically possible for the National Broadband Network Company (NBN Co) to filter internet websites, according to Mark Riley, chief technology officer of internet security company ContentKeeper Technologies, based on technology that the company already has in place.
At the beginning of this month, Telstra and Optus, among others, have begun to filter a blacklist of the "worst of the worst" child abuse sites developed by the international policing agency Interpol, under framework developed by the Internet Industry Association (IIA).
NBN Co, the company in charge of rolling out the Federal Government's $35.9 billion fibre to the home network, has previously said that as a layer two wholesale provider of internet services, it is unable to filter content. On layer two of the Open Systems Interconnect (OSI) model, NBN Co is simply responsible for "moving bits of data from a premises to a Point of Interconnect" (PoI). According to the company, all filtering would need to be on layer three — or the network layer — where data is addressed (eg, with an Internet Protocol address).
However, according to Riley, the filter provided by ContentKeeper in operation for Canberra-based internet service provider (ISP) CyberOne is blocking content over the Ethernet on layer two.
"We're actually doing the work as it leaves the CyberOne network and it goes to their upstream bandwidth provider," he told ZDNet Australia.
Riley said that filtering on this layer overcomes the simple bypass that can allow users to get around the DNS-based filters and access blocked sites by changing their DNS to one outside of the control of their internet service provider.
"Obviously, we're not vulnerable to that kind of bypassing, because the customer could be using the DNS on Mars, and we could still pick up that they were trying to get to one of the Interpol websites," he said. "Because we actually do the work at the Ethernet level, we aren't affected by DNS look ups."
Riley said that ContentKeeper had been working with the Australian Federal Police and Interpol for a year to get the filtering technology ready to market and said that ISPs are unable to dictate what content is and isn't blocked.
"We actually take an update list from Interpol, and that then goes into our system, and there's no actual way for our clients to interfere with the data. What we get from Interpol is exactly what goes into the product."
Although the company has been a supporter of the voluntary filtering scheme, Riley said that the ContentKeeper remains concerned about the government's planned mandatory internet filtering scheme.
"We've been very vocal about how concerned we are about that whole concept, particularly in terms of scope creep," he said.
Riley said that the two schemes differed, because in blocking the "worst of the worst" of child abuse websites, there were a number of steps to verify what is actually being blocked.
"Multiple police officers specialising in this field from multiple countries [are] all signing off on any particular domain, so the checks, cross-checks and balances are really well thought through and probably gold standard, as far as making sure that what actually goes on that list is the Real McCoy," he said. "It would be extremely difficult to make a mistake to the point where you get something that shouldn't be on the list being added to it."
ZDNet Australia approached NBN Co to ask whether it would be possible to use this filter, but the company had yet to provide comment at the time of publication.