Filtering technically impossible for us, says NBN Co


The National Broadband Network Company late yesterday confirmed it wouldn’t be implementing the limited filtering scheme being implemented by other Australian telcos, noting that the national network it was constructing was 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 ISP industry’s peak representative body, the Internet Industry Association. The filter, which is being seen as a more moderate industry approach developed in reaction to the Federal Government’s much more comprehensive filter scheme, will see the ISPs block a “worst of the worst” list of child pornography sites generated by international police agency Interpol.

However, a NBN Co spokesperson said late yesterday that its network wasn’t compatible with the filter as the filtering took place at a different network layer. “NBN Co is building a layer 2 open access network moving bits of data from a premises to a Point of Interconnect,” the spokesperson said. “Any internet filtering would need to be implemented at Layer 3.”

Layer 3 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 2 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 are 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.

Image credit: Mike Gieson, royalty free


  1. This is what I’ve been trying to tell people since, oh, 2009… it was one of the first bits of FUD associated with the FTTH NBN… “they’re only building this so they can filter us!!” Nice to see it from the horses mouth.

      • “Cue FUD…”
        “people spouting that rubbish have no basic understanding of networking principles.”

        FUD, like beauty, is all in the eye of the beholder.

        As NBN states, their technology will not work with THIS particular type of filtering.

        There are plenty of lawful interception and filtering devices readily available for GPON from multiple vendors (even non-Israeli ones so that Lee Rhiannon can approve their purchase).

        • “There are plenty of lawful interception and filtering devices readily available for GPON”

          Indeed, just as there are plenty of similar devices which can be used on the copper network of today. Or indeed any type of network I imagine.

          What matters is the legislation which enables such lawful interception to take place, not the technical details of the network where it’s happening. In other words, the construction or otherwise of the NBN is irrelevant to this matter – which I think is the point this article is trying to make.

    • While NBNCo can’t technically filter in this current manner, this doesn’t stop them filtering transparently. Eg, it inspects what data is being sent, and either processes it, or not. Sort of like deep packet inspection, where they look at the contents of the payload, but instead, they’re looking at the lower level packet. Though that would be pretty inefficient, cost a lot, and from memory, the NBNCo won’t be handling any international traffic which limits this even further.

      However, this does not stop mandated filtering via policy. The NBNCo could be pressured (since they are somewhat independent) by government to (after it’s setup) only supply ISPs which provide some level of filtering. This means ISPs would be forced to filter. Many people suspect that this is why Telstra and Optus suddenly said they’d filter the internet, the same week (day?) that they were handed very favourable contracts from NBNCo. A benefit of this pseudo-political approach, would be that since NBNCo is centralized, and independent, it has the right to contract how it wants (to some extent), which means they could impose mandatory filtering, without having to go through the regular governmental bureaucracy.

      Either way, it would be wrong to say it isn’t completely impossible, as there are both technical possibilities, and political possibilities for it, but I believe, due to general public opinion, it is unlikely (given present circumstances).

      Either way, we’ll see.

      • “However, this does not stop mandated filtering via policy. The NBNCo could be pressured (since they are somewhat independent) by government to (after it’s setup) only supply ISPs which provide some level of filtering. This means ISPs would be forced to filter.”

        You’re looking at it backwards. If/when the legislation is put in place, ISPs would be forced to filter no matter what. The existence of NBNCo makes this no easier or harder; once it’s law everyone has to comply, no matter which wholesale network they’re accessing.

        To be clear I’m strongly opposed to any such legislation being put in place, I’m just trying to point out that this is a legislative issue, not a technical one.

    • No, the optical lint buildup is too great. You could send a flush of ultrablue through the fibre, but you can get some light scouring from the trapped photons that way.

  2. Unfortunately there are layer 2 censorware solutions.

    While I believe the NBNco spokesperson’s comment to be accurate and made in good faith I will continue to keep an eye on it. At least until the government of the day starts to show some commonsense regarding the Internet.

    I guess it will take a new generation of politicians to stop the rot. We wil get there I guess, even if it is one funeral at a time. ;)

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