I'm a network administrator at a small college. In the past, we've kept a fairly open wireless network, but recently a few throughput issue have made us consider locking it down a bit more, in a play we predict will potentially preserve packet-passing performance for peers. Students would still be able to do almost anything over the wired connection available in each room, but the wireless would for the first time require authentication and be limited to only certain ports. Currently we're considering 53(dns), 80 & 443(web), 143, 587, 993, and 995 (email), and 1935 (flash video).
The big issue here for us is that we also give each new full-time on-campus student an iPod Touch, and so we need to make sure these devices (which are wireless only) continue to work for our students as expected. So can anyone share any iOS apps or services that use other ports that we would need to open? For example, if iTunes purchases, Location Services, Push Notifications, FaceTime, or certain well known apps require other ports, which apps and what ports do they use?
The main push behind this is density in the dorms: at certain times of day we just have too many radios active in too small a space at one time, and throughput really suffers. So the idea is to force certain traffic (especially games and torrents) to the wired connections, which can handle this much better, and thus leave the air waves more open for other devices that don't need this capability. So this is about making things work better rather than being more restrictive just because we can.
Note that this will all probably come to nothing, but I do need to at least investigate it thoroughly.