jnetcap port obtainer

package io.github.wreed12345;

import java.util.ArrayList;
import java.util.List;

import org.jnetpcap.Pcap;
import org.jnetpcap.PcapIf;
import org.jnetpcap.packet.PcapPacket;
import org.jnetpcap.packet.PcapPacketHandler;
import org.jnetpcap.protocol.tcpip.Tcp;

public class Main {

	public static void main(String[] args) {
		List<PcapIf> alldevs = new ArrayList<PcapIf>(); // Will be filled with
														// NICs
		StringBuilder errbuf = new StringBuilder(); // For any error msgs

		/***************************************************************************
		 * First get a list of devices on this system
		 **************************************************************************/
		int r = Pcap.findAllDevs(alldevs, errbuf);
		if (r == Pcap.NOT_OK || alldevs.isEmpty()) {
			System.err.printf("Can't read list of devices, error is %s",
					errbuf.toString());
			return;
		}

		System.out.println("Network devices found:");

		int i = 0;
		for (PcapIf device : alldevs) {
			String description = (device.getDescription() != null) ? device
					.getDescription() : "No description available";
			System.out.printf("#%d: %s [%s]\n", i++, device.getName(),
					description);
		}

		PcapIf device = alldevs.get(0); // We know we have atleast 1 device
		System.out.printf("\nChoosing '%s' on your behalf:\n",
				(device.getDescription() != null) ? device.getDescription()
						: device.getName());
		
		/*************************************************************************** 
         * Second we open up the selected device 
         **************************************************************************/  
        int snaplen = 64 * 1024;           // Capture all packets, no trucation  
        int flags = Pcap.MODE_PROMISCUOUS; // capture all packets  
        int timeout = 10 * 1000;           // 10 seconds in millis  
        Pcap pcap =  
            Pcap.openLive(device.getName(), snaplen, flags, timeout, errbuf);  
  
        if (pcap == null) {  
            System.err.printf("Error while opening device for capture: "  
                + errbuf.toString());  
            return;  
        }  
        
        /*************************************************************************** 
         * Third we create a packet handler which will receive packets from the 
         * libpcap loop. 
         **************************************************************************/  
        PcapPacketHandler<String> jpacketHandler = new PcapPacketHandler<String>() {  
  
            public void nextPacket(PcapPacket packet, String user) {  
                
                Tcp tcp = new Tcp();
                
                if(packet.hasHeader(tcp)) {
                	if(tcp.destination() == 80)
                		System.out.println("Web request");
                	else if(tcp.destination() == 443)
                		System.out.println("Secure Web request");
                }
            }  
        };  
        
        /*************************************************************************** 
         * Fourth we enter the loop and tell it to capture 10 packets. The loop 
         * method does a mapping of pcap.datalink() DLT value to JProtocol ID, which 
         * is needed by JScanner. The scanner scans the packet buffer and decodes 
         * the headers. The mapping is done automatically, although a variation on 
         * the loop method exists that allows the programmer to sepecify exactly 
         * which protocol ID to use as the data link type for this pcap interface. 
         **************************************************************************/  
        pcap.loop(1000000, jpacketHandler, "");  
  
        /*************************************************************************** 
         * Last thing to do is close the pcap handle 
         **************************************************************************/  
        pcap.close();  
	}
}