On Tue, 26 Nov 2013 at 12:09, Eric Koldeweij wrote:
The 65536 port limit is a client limit, not a server limit. A client can not have more than 65536 connections open to any other host at the same time (65536 is theoretical, in reality this number will be much lower).
A client can even have more connections to a single server as long as all combinations of local and remote port numbers are distinct. So, the actual (theoretical) limit is 64k^2 connections per unique combination of local and remote IP addresses.
Or in other words, it is the combination of local IP address, local port number, remote IP address and remote port number that uniquely identifies a TCP connection and if only one of these four values is different we are looking at two separate connections that can exist in parallel.