Client server commuincation

Question

When a client communicates with the server, the destination port of the traffic sent to the server, is say x, while the source port is a random number say y. While establishing multiple connections with server on the same the destination port & IP address, can it be tied to the same source port & same IP address? Is this possible? If yes, can you give any example?

Answer 1

No. The combination of [SourceIP]:[SourcePort] <-> [DestinationIP]:[DestinationPort] has to be unique for each TCP or UDP connection so for TCP or UDP there can only be one connection per tupelet.

The TCP and UDP protocols are separate though, so TCP port N and UDP port N are entirely different. This means that you could have connections that appear to share the same [SourceIP:SourcePort] and [DestinationIP:DestinationPort] as one is TCP and the other is UDP, however because of the protocol difference they don't.

Answer 2

Although IP / Port has to be unique on each end of the connection, the server will be LISTENING on a specific address / port, when the server ACCEPTS the connection it will be accepted on a DIFFERENT port. This is how the server can handle many different clients at the same time.