March 21, 2006
I’ve written several times recently about the technical details of network discrimination, because understanding these details is useful in the network neutrality debate. Today I want to talk about the role of encryption.
Scenarios for network discrimination typically involve an Internet Service Provider (ISP) who looks at users’ traffic and imposes delays or other performance penalties on certain types of traffic. To do this, the ISP must be able to tell the targeted data packets apart from ordinary packets. For example, if the ISP wants to penalize VoIP (Internet telephony) traffic, it must be able to distinguish VoIP packets from ordinary packets.
One way for users to fight back is to encrypt their packets, on the theory that encrypted packets will all look like gibberish to the ISP, so the ISP won’t be able to tell one type of packet from another.
To do this, the user would probably use a Virtual Private Network (VPN). The idea is that whenever the user’s computer wanted to send a packet, it would encrypt that packet and then send the encrypted packet to a “gateway” computer that was outside the ISP’s network. The gateway computer would then decrypt the packet and send it on to its intended destination. Incoming packets would follow the same path in reverse – they would be sent to the gateway, where they would be encrypted and forwarded on to the user’s computer. The ISP would see nothing but a bi-directional stream of packets, all encrypted, flowing between the user’s computer and the gateway.
The most the user can hope for from a VPN is to force the ISP to handle all of the user’s packets in the same way. The ISP can still penalize all of the user’s packets, or it can single out randomly chosen packets for special treatment, but those are the only forms of discrimination available to it. The VPN has some cost – packets must be encrypted, decrypted, and forwarded – but the user might consider it worthwhile if it stops network discrimination.
(In practice, things are a bit more complicated. The ISP might be able to infer which packets are which by observing the size and timing of packets. For example, a sequence of packets, all of a certain size and flowing with metronome-like regularity in both directions, is probably a voice conversation. The user might use countermeasures, such as altering the size and timing of packets, but that can be costly too. To simplify our discussion, let’s pretend that the VPN gives the ISP no way to distinguish packets from each other.)
The VPN user and the ISP are playing an interesting game of chicken. The ISP wants to discriminate against some of the user’s packets, but doesn’t want to inconvenience the user so badly that the user discontinues the service (or demands a much lower price). The user responds by making his packets indistinguishable and daring the ISP to discriminate against all of them. The ISP can back down, by easing off on discrimination in order to keep the user happy – or the ISP can call the user’s bluff and hamper all or most of the user’s traffic.
But the ISP may have a different and more effective strategy. If the ISP wants to hamper a particular application, and there is a way to manipulate the user’s traffic that affects that application much more than it does other applications, then the ISP has a way to punish the targeted application. Recall my previous discussion of how VoIP is especially sensitive to jitter (unpredictable changes in delay), but most other applications can tolerate jitter without much trouble. If the ISP imposes jitter on all of the user’s packets, the result will be a big problem for VoIP apps, but not much impact on other apps.
So it turns out that even using a VPN, and encrypting everything in sight, isn’t necessarily enough to shield a user from network discrimination. Discrimination can work in subtle ways.
Originally posted by Ed Felten from Freedom to Tinker, remediated by yatta on Mar 21, 2006 at 11:23 PM
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We've been having a back channel conversation amongst the trackers at unmediated about how/whether to update the way in which we aggregate, present, and make useable the content on the site, in light of all the various aggregators, digg and its clones, and role model group blog sites that we all consume/use/hate/love. Since we all primarily support open media movements and the freedom of bits and so forth, and with all of us being busy with our primary projects, we are looking for ways to make getting content on the site easier and more streamlined, while making it obvious that we are presenting other sources content. With the availability of open API's for just about any type of media aggegration literally getting past the saturation point, and mashups taking every possible form, we are wondering, is it time to take a step back, or a step forward with how/what we do at umediated? In the course of my surfing today, i found this new site, Boxxet Which just might be the straw that breaks the camel's back in how we all perceive the current mix and match nature of the web as it now stands. What's different about Boxxet from other aggregators and mashups like the newest entry popurls, (which aggregates digg, slashdot, reddit, newsvine, tailrank, and flickr) is that Boxxet is a Website generator. Thats right, just pop in all the urls u want to aggregate (and WHAT from them) choose how u want to format it, plug in the url that u want it to be accessed at... and whammo: Your own site with everyone elses content, and all thats left to do is decide whether googleplex or yahooza is going to be the source of your linklove revenue. And if u have on older domain that u plug this into...well, we all know how the pageranking with search engines work by now. It used to be that u had to have a bit of code knowledge to make all this stuff work. Eyebeam's Re-blog engine which powers this site was not a simple undertaking at the time that Michael Frumin and Michael Migurski put it all together... a half a year before Marc Broadband-mechanicked the term Reblog as his latest buzzword before casting his attention on the ourmedia-meme. (kudo's, kudo's) But now, with the cut and paste mentality of webculture that we at unmediated have helped create, the pace at which people are remixing and repurposing code is accelerating at a rate similar to the curve that we saw with pro-sumer desktop video... almost anyone can do it. I have this sinking feeling in my gut that we will arrive sooner than later at the same existential threshold that the film studios and record labels are squirming under to our joyful cries of "die, dinosaurs, die!". What i am wondering, is how long until my hero of the open-information movement, Cory Doctorow, and the rest of our pals at BB will tolerate re-aggregation and repurposing of his content, (now that he is investing so much more time at the site) before he (or any of one us) screams, "FOUL!" Stewart Butterfield over at Flickr is dealing with this beast at the moment...and i have to admire the dryness with which he states, "I loaded the FlickrCentral pool and firefox got up to using 240mb of ram before dying. So that's not a great user experience, but it's really terrible for Flickr. If it catches on and you don't limit it, we'll have to cut you off :\" Sure, Stewart, blame it on the user experience and firefox. ;) I admire your candor, and personal attention/approach to what has become one of the hottest new BRANDS in Web 2.0 ...that u still have time to be personal and all flickr-fuzzy even after being acquired, but I am sure that your jeans feel like they're fitting a bit tighter all of a sudden. Pretty soon, I expect, a lot of us bell-bottomed infornistas are going to wake up in a similar pair of Jordaches. I'm curious which of us will cut the inseams and sew in another totally different material to keep our style,and which of us will claim that now that we're wearing skintight jeans ("they're really really comfortable...REALLY! You think i should get a pair of Reeboks to go with 'em?"), that the manufacture of bell-bottoms should be forbidden. I point this all out in good humour only to illustrate a point: The times, they are('nt) a changin'>, and Cory just might wake up one day soon in his magic kingdom, and say "Hey, man, where'd all my whuffie go? And he's going to have no choice but to join Walt's pinstripesuits in pushing for copyright extension. It's a pill i hope he (and we) never have to swallow. So i pose the question to our community readers: How do you see unmediated-Are we crossing the boundaries in how we repurpose content? Would you like to see more editorializing? Narrower/Broader scope? Are we a repository of information that you come back to use, or just part of your daily information addiction? Let us know... I, for one, would like to have an idea about what pair of jeans to wear this year ;) michael
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