[Infowarrior] - How Comcast blocks your Internet traffic

[Richard Forno]

How Comcast blocks your Internet traffic

http://machinist.salon.com/

Bless the Associated Press for unearthing, through careful and diligent
investigation, Comcast's shameful, hidden Internet traffic-management
scheme.

Comcast, the AP determined, actively manages data on its network by using
software to essentially masquerade as its subscribers' machines. When
non-Comcast Internet subscribers request files from your Comcast-connected
machine -- as happens in peer-to-peer file-sharing applications -- Comcast's
technology steps in and tells the non-Comcast subscriber you're not
available.

This is a difficult story to explain, but it's quite important. For years,
consumer advocates have been demanding that Congress and/or the Federal
Communications Commission impose "network neutrality" regulations that would
force broadband providers (like Comcast) to treat all data on a network
equally. Lawmakers have so far failed to do so.

Broadband providers, meanwhile, insist that they do treat all traffic
equally, but they reserve the right to use certain technologies to "manage"
data on their network. The Comcast plan suggests that broadband providers
mean something very broad by "traffic management" -- including, it appears,
purposefully stepping into your network sessions to shut them down.

To understand why this whole process is so egregious, let's look at it in
FAQ format.

What is Comcast doing, and why?

The Internet is awash in peer-to-peer applications. In such programs, you
get (and send) pieces of a file from (and to) computers all over, rather
than communicating with a single big server (as you do, say, when you
download a YouTube video).

The technology first gained prominence with music- and movie-sharing apps --
Napster, Kazaa, etc. -- but today P2P tech is deployed in all kinds of
software, including for Internet phone services (Skype) and TV (Joost).
BitTorrent, one of the most popular peer-to-peer protocols, is used to
download all kinds of stuff, both legal and illegal.

Broadband providers have a love-hate relationship with peer-to-peer apps. On
the one hand, peer-to-peer programs increase the demand for high-speed
access -- many people decide to subscribe to broadband service only because
of amazing apps like Kazaa, BitTorrent, Skype and others.

But peer-to-peer programs also eat up space on a network, because every user
is downloading and uploading data for long periods of time. And for
providers, a clogged network costs money and hurts their reputation. (If
peer-to-peer users use up all the space, other users complain that their Web
surfing is too slow.)

Providers thus have an incentive to reduce peer-to-peer traffic on their
networks. But they can't do so openly because, remember, a lot of people
only pay for services like Comcast in order to use peer-to-peer programs.

Moreover, in their marketing copy, Comcast and other broadband companies
play up the "unlimited" nature of their plans. They don't really want to
tell people that, actually, they're managing their networks so that you
can't do all you want with it (though in the fine print that subscribers
never read, they all reserve the right to do so).

The upshot, then: Comcast wants to manage its traffic. It just doesn't want
people to know that it does.

So how does Comcast silently manage traffic?

The effort that the AP reports on was first discovered by Robb Topolski, a
software engineer who hangs out at the forums on DSLReports.com. In May, he
posted a detailed note on the forum describing Comcast's traffic management
operation.

The system works, Topolski guessed, by limiting communication at the
"boundary" of Comcast's network -- that is, the point where Comcast's
network connects with the larger Internet.

To detect peer-to-peer communication, Comcast inspects packets -- the
smallest meaningful bit of information on the Internet -- as they cross the
network boundary. If Comcast determines that there are too many peer-to-peer
users within its network sending files to people outside the network, it
begins to interrupt the connections between Comcast users and those beyond
Comcast.

To interrupt these communications, Comcast appears to be using technology
made by a network management company called Sandvine. What's remarkable is
how Sandvine manages to disrupt peer-to-peer traffic.

As Topolski describes it, Sandvine's system sends a "forged" packet to each
of the two computers engaged in a peer-to-peer transfer -- the forged packet
looks like it came from the other person's computer, and it basically tells
each machine that the other is unavailable, ending the transfer.

The AP describes this marvelously: "Each PC gets a message invisible to the
user that looks like it comes from the other computer, telling it to stop
communicating. But neither message originated from the other computer -- it
comes from Comcast. If it were a telephone conversation, it would be like
the operator breaking into the conversation, telling each talker in the
voice of the other: 'Sorry, I have to hang up. Goodbye.'"

So what? Isn't Comcast only stopping illegal file sharing?

No! Comcast's system doesn't look at the copyright status of the materials
you're trading -- it only looks at the technical protocols you're using to
conduct the trade, and blocks access based on those protocols alone. And
just because people use these technical protocols to trade illegal materials
doesn't mean that every use is illegal.

Case in point: To test how Comcast is managing traffic, AP reporters tried
to download a version of the King James Bible using BitTorrent. The Bible,
of course, is perfectly legal to trade; indeed, some people might say that
putting the good book up for others to download is a blessed thing.

But when AP reporters tried to download the Bible from Comcast subscribers
in Philadelphia and San Francisco, they found that the connections were
either blocked outright or delayed. (Downloads from other providers worked
fine.)

In his post, Rob Topolski points to another way Comcast's system can disrupt
legitimate traffic.

Say you have a band and you want to put up your CD on a file-sharing network
for others to download. If you're a Comcast subscriber, you would find this
very hard to do -- since Comcast limits peer-to-peer connections at the
network boundary, "the time it would take to get a complete copy of a music
file to a point outside of the Comcast network is dramatically increased,"
Topolski wrote.

OK, but so what? Even if Comcast is blocking peer-to-peer traffic, that
doesn't affect me -- all I'm doing is browsing the Web!

Sure, this only affects peer-to-peer transfers -- at least, as far as we
know. The most alarming thing about this scheme is that Comcast is
conducting it on the sly. It didn't alert anyone to its filtering mechanism
-- not its customers, not other ISPs, nobody.

Indeed, Comcast is still not coming clean. A company rep tells the AP: "We
rarely disclose our vendors or our processes for operating our network for
competitive reasons and to protect against network abuse," he said.

And then there's the sheer dishonesty of the practice. Comcast's system is
silently listening in to your Internet traffic and inserting itself into the
communication in order to shut it down.

If the company feels justified doing this on peer-to-peer connections,
what's to say it wouldn't feel similarly justified shutting down or slowing
down your communication with Amazon.com, or NYTimes.com, or YouTube or any
other online service (whether because it doesn't like the content, or
because it's got an economic incentive, or because it's just mean) -- and
all without telling us?

OK, so what can we do about this?

It'd be wonderful if the solution was to simply stop subscribing to Comcast.
If that would make you feel better, by all means, cancel your subscription.

But know this: Other broadband vendors have not distinguished themselves on
the issue of network neutrality. In general, major broadband companies say
they should be free to manage traffic on their networks, and it's impossible
to tell how expansively they understand that "management" role.

If Comcast is saving money by adopting such methods, you can bet others are
already doing so, or soon will. It would be shocking if Comcast were the
only one.

But there is an obvious solution. It has been obvious for some time. We need
a law!

Providers should be proscribed from interrupting customers' connections or,
at the very least, from doing so secretly -- if they're going to disrupt
your traffic in any way, they should be forced to tell you how.

Broadband companies have long argued that network neutrality regulations are
unnecessary. The Comcast scheme pretty definitively proves otherwise.

[Flickr picture by dmuth.