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I've got 2 sim cards from the same mobile network provider with the same "unlimited" data plan.

Card number one works great when tethering from an android phone. And also from a 4G router (mifi) device.

Card number two sometimes works with that very same android phone. But get's blocked when I use a 4G router (get redirected to a web page stating that I'm up to no good). Sometimes, when tethering from an android phone, I get very slow speeds (<1Mbps down) but very fast speeds from the phone itself.

I know that it is possible to know when someone is tethering (something to do with TTL) but how exactly do they do it?

And why does it work for sim card number one but not for sim card number two with the same data plan?

Txugo
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1 Answers1

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1 - TTL detection: If the value of TTL is less than the expected value, they can assume that there is tethering. However you can tweak Windows / Linux to send a higher value than usual.

2 - User-agent sniffing and OS fingerprinting: When your browser requests a page, it sends its user agent, version and other parameters. Networks can detect if the version of Chrome or Firefox is a desktop version. The other thing that is easy to detect is OS. Check this if you want to know how much they can detect of you.

3- Traffic/port sniffing: Networks look at what UDP / TCP ports you are using and what kind of traffic is going over them. So they can detect videogames, bitttorent, etc.

Using a VPN you can at leat disguise your traffic in a way that it is harder to apply all these techniques.

jcbermu
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