You want to see what your PL does online @ home. You somehow know his connection IP address. Which software can help you to know his system's open ports?

This is an exact duplicate of question 15181. Nmap (Network Mapper) is the correct tool for port scanning. It's designed specifically to discover open ports and services on network targets. Given an IP address, nmap scans the target and enumerates open ports with service detection. Wireshark (formerly Ethereal) is for packet capture and analysis, not port scanning. 'Switch sniffer' is not a recognized security tool.