mIRC client usually uses what ports to connect to the IRC server? I'm not refering to the server ports, but the ports used to send data over to the IRC server, eg Dalnet:6662
When your computer communicates using TCP, it opens a random port (unless you're binding and listening for incoming connections like a server). mIRC doesn't open a specific port to send data, it's the OS itself. Try using: netstat -a in a cmd.exe window.