Specifically it decrements the TTL of routed packets, so hotspot traffic will tend to have a TTL of 63 instead of 64. You could theoretically disable this at the risk of creating infinite routing loops, although android probably makes it inaccessible if the kernel has a setting for it at all, so you might have to rewrite packets in user space.

Different applications on a single device can't apply different TTL's? I thought TTL was a pretty basic knob exposed to applications. e.g. A sensor that transmits fresh data every 20 seconds doesn't need stale packets bounding around clogging up the pipes, while a file transfer over an intermittently delayed link might benefit from a higher TTL.

Voluntarily tags specific TTL values much like your home router does. Some providers assign a different IP to hotspot users.

> voluntarily tags

Aah, you mean ‘snitches’. :P

Super easy to spoof too.