Multi Threaded TCP Port Scanner allows you to scan 65535 TCP ports on an IP address. You can specify how many threads to run and the timeout. Furthermore, it will tell you the MAC address of the target and the services that are running. You can scan IP addresses on your network and find out which open ports you have.
Tenable Nessus is a world-leader in active vulnerability scanners. It features high-speed discovery, configuration auditing, asset profiling, sensitive data discovery, and vulnerability analysis of your security posture. Nessus scanners may be distributed throughout an entire enterprise, inside DMZs, and across physically separate networks. It is free of charge for personal use in a non-enterprise environment.