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AT&T trying to crackdown on unauth. tethering

arstechnica.com

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Re: AT&T trying to crackdown on unauth. tethering

#11

Post by reemrevnivek »

weaksauce wrote: post #3
paylesworth wrote: post #2

I'm curious to find out what you guys / gals think about this. Is this just a fear tactic? Or, does ATT have a legit way to check if you're doing unauthorized tethering. Any of you get hit with this text on accident (false positive)? EDIT Removed the '(Ars)' from the title. N00b mistake :)

They probably just see that you are using more bandwidth than a normal user and infer that way. If they were packet sniffing your non phone traffic they might be able to infer from a plethora of non phone headers that the system will invariably send out. (system update check in the background. Etc. )

In spite of all the other, technical ways of doing this (see your sibling comments), I fear that this is what they're doing.

Re: AT&T trying to crackdown on unauth. tethering

#12

Post by ceejayoz »

mattmanser wrote: post #7
gte910h wrote: post #5

Earlier quoted context omitted.

There are dozens of legit ways to automatically detect this, and dozens more if humans are involved. Requesting non-mobile versions of sites that do not have the option User Agent strings such as "Internet Explorer" or "Safari" in HTTP requests Sending screen sizes via relatively common web calls The use of UA-Pixels at all, especially when specifying large screen sizes. Use of protocols that are only seen in desktop…

How are any of these legit, all of that's illegal wiretapping.

It'd be illegal wiretapping if it were the government, perhaps, but I'd imagine the standard contract with AT&T permits this.

Re: AT&T trying to crackdown on unauth. tethering

#13

Post by kalvin »

Lots of discussion of this elsewhere. It looks like some people who don't tether (but use a lot of bandwidth) are also getting the message, leading people to believe to that AT&T is looking solely at bandwidth usage.

http://modmyi.com/forums/iphone-news/755094-t-cracking-down-...

I use TetherMe ($2 in the cydia store, instead of $10 for mywi, enables native tethering), and I haven't gotten this message.

Re: AT&T trying to crackdown on unauth. tethering

#15

Post by neilc »

bcrawford wrote: post #9
paylesworth wrote: post #2

I'm curious to find out what you guys / gals think about this. Is this just a fear tactic? Or, does ATT have a legit way to check if you're doing unauthorized tethering. Any of you get hit with this text on accident (false positive)? EDIT Removed the '(Ars)' from the title. N00b mistake :)

It is possible for them to detect this if they are doing Layer 7 inspection. All it would take is parsing the user agent to see that you're not on Mobile Safari. On the iPhone side, it just does a NAT and theoretically passes all information as the public IP of the phone itself. Honestly, any respectable nerd is going to have either a) a box to SSH to or b) a VPN endpoint... if you encrypt/encapsulate all traffic ori…

Assuming the IPv4 TTL issue can be worked around (see elsewhere in thread), a phone that does GBs/month of encrypted traffic over SSH would still be a signal that something suspicious is going on.

Re: AT&T trying to crackdown on unauth. tethering

#16

Post by eli »

ceejayoz wrote: post #12
mattmanser wrote: post #7

Earlier quoted context omitted.

How are any of these legit, all of that's illegal wiretapping.

It'd be illegal wiretapping if it were the government, perhaps, but I'd imagine the standard contract with AT&T permits this.

"AT&T may, but is not required to, monitor your compliance, or the compliance of other subscribers, with AT&T's terms, conditions, or policies"

And, of course, it's now well-known that the government WAS using deep packet inspection on AT&T internet traffic.

I would assume they're just looking at how much you download in a month, though. I don't think AT&T is worried about offending outliers using large amounts of mobile data by inaccurately accusing them of tethering.

Re: AT&T trying to crackdown on unauth. tethering

#17

Post by ben1040 »

kalvin wrote: post #13

Lots of discussion of this elsewhere. It looks like some people who don't tether (but use a lot of bandwidth) are also getting the message, leading people to believe to that AT&T is looking solely at bandwidth usage. http://modmyi.com/forums/iphone-news/755094-t-cracking-down-... I use TetherMe ($2 in the cydia store, instead of $10 for mywi, enables native tethering), and I haven't gotten this message.

I certainly wouldn't be surprised if that was the case that they're just going after high bandwidth users and not doing packet inspection (yet). I occasionally swap my iPhone 4 SIM to a Nexus One and use the built-in wifi tethering feature, and haven't heard from AT&T about it. On the other hand I only have used maybe 2GB of tethered data over the last year and in general run up no more than 800MB-1GB of mobile data a month.

There are people on that thread showing they used 10+GB/month, connecting their Xbox 360s to Live via their phones, etc. That certainly seems like a way to get "noticed" by AT&T.

edit: one guy on there pasted his usage from AT&T's account manager - 165 GB!

Re: AT&T trying to crackdown on unauth. tethering

#18

Post by yellowbkpk »

These e-mails from AT&T are almost always smoke and mirrors. I'm on the same data plan I had in the Cingular days and have received dozens of e-mails and texts warning me that I "may be violating my contract" and that they're going to switch me to the $60/mo plan.

I've yet to be switched away from my $10/mo data plan.

Re: AT&T trying to crackdown on unauth. tethering

#19

Post by ChuckMcM »

Add a bit of personal experience here. Google gave its employees unlocked Android phones (not once but twice :-) and some of us (like me), put our AT&T sim card into them and used them instead of our plan phone. There was a 'feature phone' data plan that was $15 unlimited and there was the $10/month 'tax' if you had an iPhone.

Using the cheaper unlimited plan worked for a long time, and then AT&T started 'automatically' switching people to the smartphone tax if their IMEI indicated they had an android phone. I did what any reasonable person would do, cancelled my AT&T contract and signed up with t-mobile :-)

Re: AT&T trying to crackdown on unauth. tethering

#20

Post by azim »

It's unlikely AT&T is doing anything fancy at this point, but there's potentially much more to detection than TTL. NAT devices make an attempt to be transparent at layer 4 and try not to interfere with it. Host OS fingerprinting can rely on a combination of options at that layer as well including but not limited to windowing scaling MSS. If AT&T cared to go the distance, it would be very difficult to get around detection without interfering with the TCP/IP stack.
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