Comment by lunar_rover

17 days ago

The most common use case for mobile data servers is probably pwned cheap/old phones forming DDoS swarms. Pure P2P over internet is very rare on mobile, no sense not blocking ingress from the perspective of ISPs.

However for that having the phone's IP not reachable has at best marginal benefits. The DDoS itself is an outgoing connection, and for command and control having the compromised phone periodically fetch instructions from a server is simpler to implement than the phone offering a port where it is reachable to receive instructions

I kind of doubt this, as the rapidly changing nature of mobile IP addresses would mean that a periodic outbound connection would still be necessary to keep the attack up-to-date on the compromised devices current IP address. At that point, you may as well have the compromised device periodically poll an attacker-controlled server for instructions rather than jump through a bunch of hoops by getting things to work over inbound connections.