Port Scanning with Java (#12767)

core-java-modules/core-java-networking-3/src/main/java/com/baeldung/portscanner/PortScanner.java

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+package com.baeldung.portscanner;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.Socket;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class PortScanner {
+    private static final int poolSize = 10;
+    private static final int timeOut = 200;
+
+    public void runPortScan(String ip, int nbrPortMaxToScan) throws IOException, RuntimeException {
+        ConcurrentLinkedQueue openPorts = new ConcurrentLinkedQueue<>();
+        ExecutorService executorService = Executors.newFixedThreadPool(poolSize);
+        AtomicInteger port = new AtomicInteger(0);
+        while (port.get() < nbrPortMaxToScan) {
+            final int currentPort = port.getAndIncrement();
+            executorService.submit(() -> {
+                try {
+                    Socket socket = new Socket();
+                    socket.connect(new InetSocketAddress(ip, currentPort), timeOut);
+                    socket.close();
+                    openPorts.add(currentPort);
+                    System.out.println(ip + " ,port open: " + currentPort);
+                } catch (IOException e) {
+                    System.err.println(e);
+                }
+            });
+        }
+        executorService.shutdown();
+        try {
+            executorService.awaitTermination(10, TimeUnit.MINUTES);
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+
+        List openPortList = new ArrayList<>();
+        System.out.println("openPortsQueue: " + openPorts.size());
+        while (!openPorts.isEmpty()) {
+            openPortList.add(openPorts.poll());
+        }
+        
+        openPortList.forEach(p -> System.out.println("port " + p + " is open"));
+    }
+}

core-java-modules/core-java-networking-3/src/test/java/com/baeldung/portScanner/PortScannerUnitTest.java

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+package com.baeldung.portScanner;
+
+import com.baeldung.portscanner.PortScanner;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+
+class PortScannerUnitTest {
+
+    private static final int nbrPortMax = 1000; // Max is 65535, number of available ports
+    private static final String ip = "127.0.0.1";
+    PortScanner portScanner = new PortScanner();
+
+    @Test public void when_Run_then_lunchPortScan() throws IOException, RuntimeException {
+        portScanner.runPortScan(ip, nbrPortMax);
+    }
+}