[gst]

Slightly offtopic but related: One of my mobile providers supports configuring public (non firewalled) IP addresses for mobile devices and when choosing that option my phone battery drains very significantly faster than otherwise. I suspect it's because all the random packets that arrive every second or so on the public interface (when NAT and firewall are disabled) either cause the radio to use a lot more battery or prevent the CPU from going into sleep mode (or both of that).

[foobarian]

That reminds me of when I had a computer with spinning rust hard drives on my desk in grad school. At some point I was trying to focus but there was a periodic, roughly once a second hard drive noise that was driving me nuts. Went through the usual suspects at the time like the background locatedb updater, and eventually ended up finding that some bot was trying to ssh login once per second going down a list of passwords, and the errors were being logged to disk. Need I mention the computer had a public IP address?

[lxgr]

I've been wondering about that! A long time ago, I had a phone plan like that as well (in fact, a public IPv4 was the only option), and I was wondering if random port scanning would eventually use up all of my data allowance.

Turns out stateful firewalls aren't just a security factor on mobile internet connections.

[korhojoa]

I've luckily mostly been on unlimited data plans, so I don't know about it using up your data, but I guess it would? Your device is sending and receiving data. I don't think there's a distinction for externally made connections, otherwise vpn tunnels would have been really popular.

I did have an experience with my phone being suddenly used by random internet users. I had ampache running on my n900 (maemo/debian-based) and somebody found it on the internet and started streaming my music. :D I had a higher-than-normal amount of battery usage for a few days so I decided to see what's using it and discovered that my music was being played and downloaded.