Filter technically impossible for us: NBN Co

The National Broadband Network Company (NBN Co) confirmed late yesterday that it wouldn't be implementing the limited filtering scheme being put into place by other Australian telcos, noting that the national network it is constructing is incompatible with the type of technology being used in the filter.

Along with Telstra, Optus has pledged to implement a voluntary filtering framework, developed by the internet service provider industry's peak representative body, the Internet Industry Association (IIA). The filter will see the ISPs block a "worst of the worst" list of child pornography sites generated by international police agency Interpol.

However, NBN Co said late yesterday that its network isn't compatible with the filter, as the filtering took place at a different network layer. "NBN Co is building a layer two open access network, moving bits of data from a premises to a Point of Interconnect," it said. "Any internet filtering would need to be implemented at layer three."

Layer three is otherwise known as the network layer under the widely used seven-layer model of computer networking, and is responsible for routing delivery of network packets. The filtering scheme being promulgated by the IIA sees the ISPs add a blacklist of banned addresses into ISPs' DNS servers.

In comparison, NBN Co is building its own network on layer two of the seven layers, otherwise known as the link layer. This layer oversees the transfer of data between adjacent network nodes. An example of a data link layer might be the Ethernet or PPP network standards.

The move will allay fears that NBN Co could impose the voluntary filter on customers of its wholesale service. The government-owned telco does not aim to provide retail services to customers, but, rather, will only sell its services to other telcos, who will then provide services to end-users. Eventually, every major telco and ISP in Australia will be expected to be using NBN Co's network in some way.

The news comes as a substantial split has emerged in the ranks of Australia's ISPs regarding the IIA's scheme. Telstra and Optus, which between them boast the majority of Australia's broadband customers, are supporting the IIA's framework, and Telstra's implementation of the filter has already gone live.

However, others, such as Internode, iiNet and TPG, are not implementing the filter for now, preferring instead to see how the issue plays out from a law enforcement point of view. With telcos such as Optus admitting that the filter can be defeated with trivial changes to users' DNS settings on their PCs, Internode and digital rights group Electronic Frontiers Australia have labelled the IIA's initiative as "security theatre" — an initiative which won't actually increase security, just the appearance of it.