Building Java Client/Server Applications with TCP. Part 3

Building Java Client/Server Applications with TCP. Part 3

Time for our third installment in the series. This time we look at the port scanner program.

 

3. The port scanner program

 

We’ll present a port scanner program that shows which ports are open on your computer, on someone else's computer, or on an Internet server. In order to achieve this, the program browses through a given range of ports, creates a socket and tries to connect to the server on each port.

port scanner program.PNG

 

In order to use this program, you have to pass 3 arguments to it: the server, the start port and the end port. This is the result of running the program with the arguments “www.google.com 70 90”.

port scanner program results.png

 

This shows that, on www.google.com, port 80 is open – it is the HTTP port waiting for connections.

 

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Tudose, Florin-Catalin , Java Champion; Java Chapter Lead; Author at Pluralsight and Manning

Tudose, Florin-Catalin Tudose author linkedin

Java Champion; Java Chapter Lead; Author at Pluralsight and Manning

Tudose, Florin-Catalin , Java Champion; Java Chapter Lead; Author at Pluralsight and Manning

Tudose, Florin-Catalin Tudose author linkedin

Java Champion; Java Chapter Lead; Author at Pluralsight and Manning