Why ISP-level Anti-Porn Filters will not Slow Down the Web

Quite often the same arguments are used by opponents of the introduction of voluntary IP-level filters that would prevent most pornography from coming into the home. These can be divided into technological and ideological arguments. This is the first in a series of articles which will address the concerns, starting with some of the technological points often raised. They are written in consultation with Leigh Porter, a Systems Architect who has worked at UK Broadband for several years who has kindly provided clarification and correction where it was needed.

Network Level Filters will Slow Down the Internet: It is argued by some that ISP-level anti-porn filters would slow down the speed of the web. This may have been true a few years ago, but is not true today as (1) infrastructure and analysis algorithms have improved and (2) only a limited amount of data needs to be filtered.

ISPs routinely use Deep Packet Inspection of all web traffic and data transfer, passing the data through DPI filters. DPI is used, in the US, to comply with Calea requirements. It is also used globally, among other things, to help with network security, enforce service level agreements and preferentially allow normal web traffic through while restricting the bandwidth used by Peer to Peer (P2P) services such as BitTorrent.

Modern DPI filters handle up to 30Gb per second (Gbps)of traffic. A few years ago DPI filters could only cope with up to 10Gbps speeds and DPI filtering could have some impact on network speeds. However, with the introduction of faster filters and better filtering algorithms this is no longer the case. As stated by TechRepublic:

“What makes DPI all the more impressive is that the packet analysis happens in real time, with data stream throughput approaching 20-30 Gb. … With no loss of throughput, ISPs … insert these devices directly in their data streams, forcing all traffic to pass through the devices. Procera, Narus, and Ellacoya are front-runners in development of this technology, having placed equipment throughout the world”

Google already provides SeafeSearch options for Google Search, providing filtering services for all traffic that proceeds through its servers while performing search. Other search engines also provide similar services and there are no reports of such activities slowing down user experience.

In addition, not web traffic will need to be filtered. Pornographic websites must be hosted on a server. All servers have IP addresses, and the filtering would only need to be applied to traffic directed to those servers. Thus, while servers can hold hundreds of websites each, only a relatively small number of servers would need to be monitored.

Added to this is the fact that filtering will only be required for clients who have chosen to have the ISP-level filter turned on. One last point is that the PC level filter, by the very way it works, directing traffic to a proxy that checks a list and then releases the request, is likely to be slower than the ISP-level filter.

Conclusion: It can be confidently stated that ISP-Level filters will not slow down web traffic.

© Peter Watts 2011

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5 Responses to “Why ISP-level Anti-Porn Filters will not Slow Down the Web”

  1. peterb Says:

    But what can dpi do against ssl encrypted traffic? Absolutely nothing, that’s what. Introducing this sort of tech will simply result in porn sites moving to using https rather than http, a trivial adjustment on their part. Appart from the fact that turning a network provider into a content filter is a bad idea, it’s simple to bypass.

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  2. pwatts2 Says:

    Hi Peter, this article was mostly about whether the use of ISP-level anti-pornography filters would slow down the web. I will be dealing with SSL and other issues later, otherwise it would have got too long! I think that DPI would still be able to interrogate the domain and server IP, which can then be used in filtering, but will come back to you on that when I have a proper answer.

    Another point is the use of proxies, but again I will address that in another article, along with SHH Tunnelling and some other concerns.

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  3. peterb Says:

    It wouldn’t need to be deep packet inspection to identify the domain or IP address, that’s way easy to do.

    My two objections to porn filtering at the ISP level remain completely unanswered:

    1) It is technically not possible, primarily due to SSL encryption (which I’d like to see used for all traffic), but also many other reasons.

    2) The introduction of a technology which enables an authority to block what can be seen (whether for the purposes of blocking ‘adult’ content or not) is going to give an opportunity for it to be used for something else, and then something else, and then something else. If Henry VIII had this technology William Tyndale would have never got his translation of the bible published.

    Why not use it to block all websites which have instructions to build a bomb?
    Why not use it to block all websites which have instructions on lock-picking?
    Why not use it to block all websites which deny the holocaust?
    Why not use it to block all websites which strongly support the traditional view of sexual morality.

    That might sound far-fetched, but I’m of the opinion that freedoms which are given away cheaply can only be bought back at a high price.

    A much better approach is for individuals to either specifically choose an ISP who offer this sort of thing as an additional service (http://www.christiantechnology.co.uk/ I think do this) or to configure your home router so that all traffic which passes through it can be filtered.

    The only winners in ISP-based filtering (as far as I can see) are going to be the manufacturers of the equipment used to do the filtering.

    I don’t mean to suggest that porn isn’t a problem, and I’d much rather it wasn’t there, but this sort of thing is the wrong solution, it won’t work and it will have a negative effect on the Gospel.

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  4. ISP anti-Pornography Fitlers: Easy to Break Them? « In 80 Clicks Says:

    […] In 80 Clicks Web ideas, issues and other thoughts. « Why ISP-level Anti-Porn Filters will not Slow Down the Web […]

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