Ports being used by a service

[dougie1809]

Hi,

Im writing a port scanner program in java, and when run it determines any ports opened in the system. How can I find what service is using that port being opened?
Thanks.

[eRaaaa]

You could use JNI (or a library that use it) and use system services/files e.g. /etc/services
Or if you have access to the internet you could ask IANA :D

		URL iana = new URL("http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml");
		int port = 80;
		String protocol = "tcp";
		DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
		Document doc = db.parse(iana.openStream());
		XPathExpression expr = XPathFactory.newInstance().newXPath().compile("//record[number="+port+" and protocol='"+protocol+"']/name"); //or/and description ...
		Node name = (Node) expr.evaluate(doc, XPathConstants.NODE);
		System.out.println(name.getTextContent()); //http

[dougie1809]

Oh I see. Thanks. But what this is doing is, searching the web for the ports that can be used by services?
What Im trying to do is to determine what opened ports are being used by what services on the local system. Because im only scanning my computer's ports, not remote computers.
Thanks

[eRaaaa]

"what opened ports are being used by what services on the local system. Because im only scanning my computer's ports, not remote computers"

its already clear to me, but about what services are you talking about? Well known ports? User ports? Dynamic ports? :D

[dougie1809]

Hm I suppose all ports :D. Like all tcp and udp ports ranging from 1-65535. If you open up the command prompt and type in 'netstat -an', you will see all ports which are opened, and they are the ports that I'd like to find what services are using those ports?
Thanks

[Tolls]

It is likely (unless there's a handy package somewhere in Java) that you'll have to do a Runtime.exec() using that command and then read the process stream to see what's returned. That might also be quicker than trying to find a proper Java package.

[dougie1809]

Oh yes, I actually have a method to take command String arguments which uses the command line and outputs the result in java. So I can use the command 'taskkill' to kill processes by their PID. But the porblem is, I dont know how to find out what ports they have opened? If I can find that command(s) to do so, that should be happy days :)
Thanks

[Tolls]

That becomes an OS question, really, as that is entirely OS-dependent.