The TCP Port Scan tool allows for TCP ports to be scanned to see if they are in use. This can only be done to a networked device. If the functions of a server are well defined, then the administrator will be able to justify the existence of each and every open port. An external tool is the best method to determine that no additional ports are active. This would indicate that unnecessary services are running, and therefor there is unnecessary additional risk of an external exploit being used against the host. The presence of unexplainable ports may indicate that the system has been compromised to some extent.
To use the tool, enter the host, select the IP address that you wish to send requests from (they must be an IP configured for your computer), select the range and click on the Go button. The scanner makes use of 'Half Open' port technique to obtain the fastest results. You should ONLY scan systems that are under your administration or for which you have explicit permission to scan. Administrators take a grim view to others scanning their systems.
The advanced options include a Delay (in milliseconds) and a Timeout (in Seconds). The Delay defines the time waited between each pocket sent. Without a delay your system will become very sluggish during the scan. The Time-Out defines how long the system will wait for a response, before deciding that no response will be received.
During a scan a progress bar is shown next to the query. Any ports found are shown along with the name of the port. The name is obtained from RFC1700. If you wish to alter the names or add additional then edit the RFC1700.txt with any text editor.