PortWalker

PortWalker is a port scanning application with lots of features enabling you to analyze your network for security leaks and other information. You can find out who has port 80 opened, what IPs are hosted by printers or just what ports you have opened. Search for ports of a specific IP or scan the whole network for one port.
Therefore it connects to a specific ip:port using TCP. This takes one second, but the application uses multiple threads (100+) to brute force faster.

If you want to find out more about a specific IP address, click on "Remote information" and find out everything about the target computer.