is there a list of what ports are least likely to be blocked by firewalls?

@unnick 25565

realistically probably anything but email ports and udp RTMP and maybe SMB, with 80 and 443 being 100% available

@unnick Probably 80/443 or 53. Although on my school network it's actually everything but 80/443 (they have some sort of MitM proxy running on those ports but everything else is uncensored)