Socket client - server: issue: port in use on client side

Question

C# socket application :

Ther server is runing on a dedicated port and client obtain connection to it along with the server IP adr. When I'm writing out information about the connection on serverside, i can see the client IP adress as well as the port used at client.  I have not spesified any dedicated port
to use on client side, guess it just pick a port not in use from the free range IP ports.

Using Async socket comunication, data transpher both ways.

The question: How can I controll the port in use on clientside when establish the connection against server ?


The underlying worry is when the application is to bee deployed in a seting where firewall has to bee configured on trafic in both direction - ther serverside wher port is set is no problem,
but I have so far not been able to take kontrol on client side port to bee used in the socket session

Tanks to contribution!