CODEWITHSUNDEEP
c#sockets
ShinoLexTazy
ShinoLexTazy

Reputation: 77

c# Socket.RemoteEndPoint shows different port that I'm using to connect

I've developed a basic console application that will work as server-client. My general workflow will be like, Server starts clients connect to server and once a client send something the server will receive it and send it to ALL clients. Currently I can do this with my codes but my question is when I send back I've tested Socket.RemoteEndPoint and I saw ports like 65xxx. Like my first client had 65020, second 65021 and so go on. I wonder why this happen since I connect with using 9001 port and listen to 9001 port on my computer. I've done a little bit research but couldn't find a solution to my question. Why do I get these port numbers when I use Socket.RemoteEndPoint? It's okay for me since I don't use firewall or anything while I'm testing to even if the clients connects from another ports it's fine by me as long as its works but what if I have a firewall and I open ONLY 9001 port? Will my client-server based programs work then?

Upvotes: 1

Views: 899

Answers (1)

Damien_The_Unbeliever
Damien_The_Unbeliever

Reputation: 239724

So far as the server/firewall on that machine is concerned, what normally matters is the server port. You wouldn't normally apply any filtering based on the client's port, which as I said in a comment, will normally be an ephemeral port. Under most circumstances, client code will make no effort to specify the local port or IP address and will let the OS pick appropriate values.

The Socket class's LocalEndPoint and RemoteEndPoint use "local" and "remote" to mean "from the perspective of the machine on which this code is running", not "who initiated the connection vs who was connected to".

So on the server, LocalEndPoint will give you information about the server end of the connection and RemoteEndPoint will give you information about the client end of the connection. Irrespective of who initiated the connection.

Upvotes: 2

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