Hi folks if anyone can help me with this it would be appreciated as its been a while since i have programmed Below are two sets of code. The first draws a simplegui with a textarea. The second is a piece of code given to me to capture packets off the network card and displays them in a terminal. If anyone knows how it will be possible so that when the start button on my application is pressed the packets are printed to the gui text area. I have added an actionlistener to the button but i am unsure of the next step. i have been told one option is to have my program implement jpcap handler but as i havent programmed for a while im struggling with syntax. If anyone has suggestions they would be appreciated. Heres my code any how: import javax.swing.*; import java.awt.*; import java.awt.event.*; import jpcap.*; public class Servercapture extends JFrame implements ActionListener { private JFrame window; private MenuBar bar; private MenuItem about; private Menu help; private MenuItem start; private Menu capture; public Servercapture() { // Create frame and panels for GUI window = new JFrame("Network Packet Sniffer"); window.setSize(700,500); window.setVisible(true); window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel panel = new JPanel(); GridLayout gridLayout = new GridLayout(2,1); panel.setLayout(gridLayout); // Add textarea for packet capture diaplay TextArea text = new TextArea("Packet Capture Off",18, 30, TextArea.SCROLLBARS_NONE); panel.add(text); window.getContentPane().add(panel); window.show(); bar = new MenuBar(); window.setMenuBar(bar); about = new MenuItem("About"); help = new Menu("Help"); start = new MenuItem("Start"); start.addActionListener(this); capture = new Menu("Capture"); capture.add(start); bar.add(capture); help.add(about); bar.add(help); window.setVisible(true); } public void actionPerformed(ActionEvent e){ Object source = e.getSource(); if (source == start) { } } public static void main(String[] args){ Servercapture s = new Servercapture(); } } ******************************************************************** import jpcap.*; class Tcpdump implements JpcapHandler { public void handlePacket(Packet packet){ System.out.println(packet); } public static void main(String[] args) throws java.io.IOException{ String[] lists=Jpcap.getDeviceDescription(); System.out.println("Start capturing on "+lists[0]); Jpcap jpcap=Jpcap.openDevice(Jpcap.getDeviceList()[0],1000,false,20); jpcap.loopPacket(-1,new Tcpdump()); } Thanks folks

I just combined your 2 classes, with some minor mods to Servercapture (TextArea is now member variable, NOT local to constructor), implements JpcapHandler, and loopPacket (in menu handler) is passed 'this' as the Handler object. import javax.swing.*; import java.awt.*; import java.awt.event.*; import jpcap.*; public class Servercapture extends JFrame implements ActionListener, JpcapHandler { private JFrame window; private MenuBar bar; private MenuItem about; private Menu help; private MenuItem start; private Menu capture; private TextArea text; public Servercapture() { // Create frame and panels for GUI window = new JFrame("Network Packet Sniffer"); window.setSize(700,500); window.setVisible(true); window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel panel = new JPanel(); GridLayout gridLayout = new GridLayout(2,1); panel.setLayout(gridLayout); // Add textarea for packet capture diaplay text = new TextArea("Packet Capture Off",18, 30, TextArea.SCROLLBARS_NONE); panel.add(text); window.getContentPane().add(panel); window.show(); bar = new MenuBar(); window.setMenuBar(bar); about = new MenuItem("About"); help = new Menu("Help"); start = new MenuItem("Start"); start.addActionListener(this); capture = new Menu("Capture"); capture.add(start); bar.add(capture); help.add(about); bar.add(help); window.setVisible(true); } public void actionPerformed(ActionEvent e){ Object source = e.getSource(); if (source == start) { try { String[] lists=Jpcap.getDeviceDescription(); text.setText("Start capturing on "+lists[0]+"\n"); Jpcap jpcap=Jpcap.openDevice(Jpcap.getDeviceList()[0],1000,false,20); jpcap.loopPacket(-1,this); } catch (java.io.IOException ex) { System.err.println("Error: " + e) ; } } } public void handlePacket(Packet packet){ text.append(packet.toString() + "\n"); } public static void main(String[] args){ Servercapture s = new Servercapture(); } } It works when I run it to monitor PPP adapter, so I don't see why it wouldn't work with NIC.