[peterwwillis]

When most mobile providers get you on the internet, it's through NAT. They're already terminating and re-creating your connections for you, and not providing your "real" tcp/ip packets to the internet, and thus neither the world's "real" internet packets to you. All you get is a translation.

You've never gotten "the real internet" on a mobile device. The idea that they may change one more part of your fake connection seems pretty irrelevant.

The same happens on "real" routers, firewalls, etc when they massage the traffic going through them. Sometimes they barely change anything at all. Sometimes they make minor adjustments. Sometimes major ones. You don't have an agreement with any of them specifically to modify your packets; they just do. So do you have a claim of harassment against your packets? Have they trespassed on your property? Are you trespassing on their routers?

The answer to all these questions is: nobody has ever guaranteed to you what you get from the internet, other than "availability" if you're a business user, and even that's not set in stone.

[srj]

NAT doesn't terminate and recreate connections. It modifies packet headers and forwards them.

Modifying headers in order to facilitate transit over a network is one thing, modifying the L7 payload is another.

[peterwwillis]

Well you're right in a sense. But it modifies packets to a point where they are indistinguishable from the original connection, and tracks the incoming and outgoing interface sides as if they were discrete connections (there are at least four flows for every NAT connection).

Often carrier-grade routers will replace every aspect of a tcp/ip packet, like sequence numbers, windows, flags, source and dest ports, etc. Routers like these see everything going through them as a form of NAT; it's just some connections are modified more than others. The exception to this would be interfaces in bridge or monitor mode.

To your second point that modifying some layers is OK but modifying other layers is not: what rationale explains this double standard? What about the application layer do you find to be unique in that there's some expectation of purity? Does a proxy not modify layer 7 to cache and pass traffic? Does DNS not do the same?

[selectodude]

Verizon LTE devices have a unique, publicly accessible IPv6 address.