Comments on: ISP Filtering: Where’s the Line?

By: fleeep

fleeep — Sun, 31 Aug 2008 02:51:16 +0000

Great post and great analysis, spam filtering can be such a double edged sword and blacklist/whitelist solutions seem inadequate in my experience. Dunno how much spam crap you get in your email/blog site but I’m really amazed these days at the sheer volume that gets through the filters.

By: jtgraves

jtgraves — Wed, 16 Jul 2008 22:42:59 +0000

That’s an excellent question about how the blocking will work. It probably won’t be any more granular than per-IP blocking. I can’t find any details on how the NCMEC will get the list of sites to Qwest, but my first guess would be a manual process involving phone calls or e-mails. Then again, maybe I’m underestimating the number of sites involved.

By: Michael Janke

Michael Janke — Tue, 15 Jul 2008 02:38:37 +0000

I’m curious how they block the sites. They presumably don’t have a giant web proxy or the great firewall of Qwest. Perhaps they’ll null route the offending IP addressed?

If so, the possibility for error exists, and could potentially be interesting. Suppose the NCMEC sends Qwest a list with a misplaced wildcard.

By: Derek Bambauer

Derek Bambauer — Tue, 15 Jul 2008 01:17:11 +0000

Jim, these are great points. The spam one is rarely mentioned in discussions of filtering. Virtually no one would contest that ISPs should filter spam e-mail messages. I proposed at one point that ISPs should filter the URLs contained in spam – in other words, if a user clicks a link in a spam message, the ISP would blackhole that HTTP request. (I still think this is a good idea, though it could be problematic.) Yet that’s also a form of information control, and it’s very hard these days to find an ISP who will let you receive all the spam you want.

Having ISPs block offshore child porn sites could be quite helpful – it would likely reduce the economic viability of such sites and, hopefully, reduce child abuse. There are 3 concerns here. First, URL filtering is expensive, and ISPs are going to be reluctant to do this on a large scale. This means they’ll likely either do this crudely (e.g., IP address blocking), or they’ll press the government to pay for it. Second, the information I’ve seen suggests that a fair amount of child porn is hosted here in the U.S. This is worrisome in its own right, and it also suggests that foreign filtering won’t be as helpful as we might think. Finally, child porn isn’t the only evil out there. I’m reluctant to recommend filtering – a blunt policy instrument – as a remedy, given that there will be advocates for other (entirely worthy) content restrictions who will want it as well.

Finally, you raise good points about the Center for Missing and Exploited Children. The situation seems analogous to the role of the Internet Watch Foundation in the UK, except possibly that the NCMEC operates (I believe) on less clear legal authority. Procedural protections seem particularly important when there is a quasi-NGO involved, and where authorities will (understandably) be reluctant to publish their block list.

Thanks for the cogent analysis!