Euh... t'as lu l'article ?
"Port 0 is officially a reserved port in TCP/IP networking, meaning that it should not be used for any TCP or UDP network communications."
"port 0 is a programming technique for specifying system-allocated (dynamic) ports"
"[] network programmers can instead specify port 0 as a connection parameter. That triggers the operating system to automatically search for and return the next available port in the dynamic port number range."
Donc si tu demandes le port 0 on t'en donne un automatiquement. Tu ne peux pas l'utiliser directement.