Till Maas <till.m...@till.name> writes: >> |- if (!legal_ipv4_port (port)) >> |+ if (port != 0 && !legal_ipv4_port (port)) > > I am pretty sure that it is possible to listen on port 0,
not on linux; e.g. see in net/ipv4/inet_connection_sock.c the implementation of | /* Obtain a reference to a local port for the given sock, | * if snum is zero it means select any available local port. | */ | int inet_csk_get_port(struct sock *sk, unsigned short snum) and its caller. Windoze seems to have a similar mechanism accordingly http://msdn.microsoft.com/en-us/library/ms737550%28VS.85%29.aspx | Binding to a specific port number other than port 0 is discouraged for | client applications since there is a danger of conflicting with | another socket already using that port number on the local computer. RFC 768 states | Source Port is an optional field ... If not used, a value of zero is | inserted. which implies that port 0 is something special which is not to be used for normal communication. Enrico
