what the port 0 is used for?
 

recently I used a port-scan tool,and I found that the port 0 in my machine is openned for all,does it have any bad effect on the security of my system?and what is port 0 userd for?
Thanks for all in advance.

Kind Regards,
G.g

This link explains it. -->http://compnetworking.about.com/od/t...-numbers-0.htm

Thanks for all. the link is useful,content as below.
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. However, port 0 sometimes takes on a special meaning in network programming, particularly Unix socket programming. In that environment, port 0 is a programming technique for specifying system-allocated (dynamic) ports.
Configuring a new socket connection requires assigning a TCP or UDP port number. Instead of hard-coding a particular port number, or writing code that searches for an available port on the local system, 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.
Unix, Windows and other operating systems vary slightly in their handling of port 0.

Well, not sure I agree with that. Ports have been listed as common but there is no law that they must be on those ports. You don't need to register any port. You simply use a port as you wish. If it interferes then you would have to fix one or the other. I have used stuff over port 80 to get past firewalls for example. I know people who's ISP blocks port 80 at their home so they run http server on some other port that is open. Many people move remote desktop ports to help secure the connection.