网络协议分析-http/https/tcp/udp
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文章目录
TCP三次握手/TCP三次挥手
“三次握手”的目的是“为了防止已失效的连接请求报文段突然又传送到了服务端，因而产生 错误”。主要目的防止 server 端一直等待，浪费资源。换句话说，即是为了保证服务端能收 接受到客户端的信息并能做出正确的应答而进行前两次(第一次和第二次)握手，为了保证客 户端能够接收到服务端的信息并能做出正确的应答而进行后两次(第二次和第三次)握手。
“四次挥手”原因是因为 tcp 是全双工模式，接收到 FIN 时意味将没有数据再发来，但是还是 可以继续发送数据。
TCP三次握手
TCP四次挥手
完整报文
# 三次握手:SYN=1 Seq=0No. Time Source Destination Protocol Length Info 50 7.055660280 127.0.0.1 127.0.0.1 TCP 74 44156 → 12345 [SYN] Seq=0 Win=65495 Len=0 MSS=65495 SACK_PERM TSval=2731439096 TSecr=0 WS=128Frame 50: 74 bytes on wire (592 bits), 74 bytes captured (592 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.312489778 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.312489778 seconds [Time delta from previous captured frame: 0.004110298 seconds] [Time delta from previous displayed frame: 0.000000000 seconds] [Time since reference or first frame: 7.055660280 seconds] Frame Number: 50 Frame Length: 74 bytes (592 bits) Capture Length: 74 bytes (592 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP SYN/FIN] [Coloring Rule String: tcp.flags & 0x02 || tcp.flags.fin == 1]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 44156, Dst Port: 12345, Seq: 0, Len: 0# 三次握手:SYN1 ACK=1 Seq=0No. Time Source Destination Protocol Length Info 51 7.055692471 127.0.0.1 127.0.0.1 TCP 74 12345 → 44156 [SYN, ACK] Seq=0 Ack=1 Win=65483 Len=0 MSS=65495 SACK_PERM TSval=2731439096 TSecr=2731439096 WS=128Frame 51: 74 bytes on wire (592 bits), 74 bytes captured (592 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.312521969 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.312521969 seconds [Time delta from previous captured frame: 0.000032191 seconds] [Time delta from previous displayed frame: 0.000032191 seconds] [Time since reference or first frame: 7.055692471 seconds] Frame Number: 51 Frame Length: 74 bytes (592 bits) Capture Length: 74 bytes (592 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP SYN/FIN] [Coloring Rule String: tcp.flags & 0x02 || tcp.flags.fin == 1]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 12345, Dst Port: 44156, Seq: 0, Ack: 1, Len: 0# 三次握手:Ack=1 Seq=1No. Time Source Destination Protocol Length Info 52 7.055725041 127.0.0.1 127.0.0.1 TCP 66 44156 → 12345 [ACK] Seq=1 Ack=1 Win=65536 Len=0 TSval=2731439096 TSecr=2731439096Frame 52: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.312554539 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.312554539 seconds [Time delta from previous captured frame: 0.000032570 seconds] [Time delta from previous displayed frame: 0.000032570 seconds] [Time since reference or first frame: 7.055725041 seconds] Frame Number: 52 Frame Length: 66 bytes (528 bits) Capture Length: 66 bytes (528 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP] [Coloring Rule String: tcp]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 44156, Dst Port: 12345, Seq: 1, Ack: 1, Len: 0# 客户端发送消息 Hello, server!.No. Time Source Destination Protocol Length Info 53 7.057834891 127.0.0.1 127.0.0.1 TCP 81 44156 → 12345 [PSH, ACK] Seq=1 Ack=1 Win=65536 Len=15 TSval=2731439098 TSecr=2731439096Frame 53: 81 bytes on wire (648 bits), 81 bytes captured (648 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.314664389 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.314664389 seconds [Time delta from previous captured frame: 0.002109850 seconds] [Time delta from previous displayed frame: 0.002109850 seconds] [Time since reference or first frame: 7.057834891 seconds] Frame Number: 53 Frame Length: 81 bytes (648 bits) Capture Length: 81 bytes (648 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp:data] [Coloring Rule Name: TCP] [Coloring Rule String: tcp]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 44156, Dst Port: 12345, Seq: 1, Ack: 1, Len: 15Data (15 bytes)0000 48 65 6c 6c 6f 2c 20 73 65 72 76 65 72 21 0a Hello, server!.# 服务端应答No. Time Source Destination Protocol Length Info 54 7.057859991 127.0.0.1 127.0.0.1 TCP 66 12345 → 44156 [ACK] Seq=1 Ack=16 Win=65536 Len=0 TSval=2731439098 TSecr=2731439098Frame 54: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.314689489 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.314689489 seconds [Time delta from previous captured frame: 0.000025100 seconds] [Time delta from previous displayed frame: 0.000025100 seconds] [Time since reference or first frame: 7.057859991 seconds] Frame Number: 54 Frame Length: 66 bytes (528 bits) Capture Length: 66 bytes (528 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP] [Coloring Rule String: tcp]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 12345, Dst Port: 44156, Seq: 1, Ack: 16, Len: 0# 服务端发送消息 Server received: Hello, server!.No. Time Source Destination Protocol Length Info 55 7.059237157 127.0.0.1 127.0.0.1 TCP 98 12345 → 44156 [PSH, ACK] Seq=1 Ack=16 Win=65536 Len=32 TSval=2731439100 TSecr=2731439098Frame 55: 98 bytes on wire (784 bits), 98 bytes captured (784 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.316066655 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.316066655 seconds [Time delta from previous captured frame: 0.001377166 seconds] [Time delta from previous displayed frame: 0.001377166 seconds] [Time since reference or first frame: 7.059237157 seconds] Frame Number: 55 Frame Length: 98 bytes (784 bits) Capture Length: 98 bytes (784 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp:data] [Coloring Rule Name: TCP] [Coloring Rule String: tcp]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 12345, Dst Port: 44156, Seq: 1, Ack: 16, Len: 32Data (32 bytes)0000 53 65 72 76 65 72 20 72 65 63 65 69 76 65 64 3a Server received:0010 20 48 65 6c 6c 6f 2c 20 73 65 72 76 65 72 21 0a Hello, server!.# 客户端还给了一个回应No. Time Source Destination Protocol Length Info 56 7.059273656 127.0.0.1 127.0.0.1 TCP 66 44156 → 12345 [ACK] Seq=16 Ack=33 Win=65536 Len=0 TSval=2731439100 TSecr=2731439100Frame 56: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.316103154 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.316103154 seconds [Time delta from previous captured frame: 0.000036499 seconds] [Time delta from previous displayed frame: 0.000036499 seconds] [Time since reference or first frame: 7.059273656 seconds] Frame Number: 56 Frame Length: 66 bytes (528 bits) Capture Length: 66 bytes (528 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP] [Coloring Rule String: tcp]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 44156, Dst Port: 12345, Seq: 16, Ack: 33, Len: 0# 四次挥手 1 FIN=1 Ack=33 Seq=16No. Time Source Destination Protocol Length Info 57 7.062253079 127.0.0.1 127.0.0.1 TCP 66 44156 → 12345 [FIN, ACK] Seq=16 Ack=33 Win=65536 Len=0 TSval=2731439103 TSecr=2731439100Frame 57: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.319082577 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.319082577 seconds [Time delta from previous captured frame: 0.002979423 seconds] [Time delta from previous displayed frame: 0.002979423 seconds] [Time since reference or first frame: 7.062253079 seconds] Frame Number: 57 Frame Length: 66 bytes (528 bits) Capture Length: 66 bytes (528 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP SYN/FIN] [Coloring Rule String: tcp.flags & 0x02 || tcp.flags.fin == 1]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 44156, Dst Port: 12345, Seq: 16, Ack: 33, Len: 0# 四次挥手 2 ACK=17 Seq=33No. Time Source Destination Protocol Length Info 58 7.110165407 127.0.0.1 127.0.0.1 TCP 66 12345 → 44156 [ACK] Seq=33 Ack=17 Win=65536 Len=0 TSval=2731439151 TSecr=2731439103Frame 58: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.366994905 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.366994905 seconds [Time delta from previous captured frame: 0.047912328 seconds] [Time delta from previous displayed frame: 0.047912328 seconds] [Time since reference or first frame: 7.110165407 seconds] Frame Number: 58 Frame Length: 66 bytes (528 bits) Capture Length: 66 bytes (528 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP] [Coloring Rule String: tcp]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 12345, Dst Port: 44156, Seq: 33, Ack: 17, Len: 0# 四次挥手: 3 Fin=1 Ack=17 Seq=33No. Time Source Destination Protocol Length Info 61 7.390471256 127.0.0.1 127.0.0.1 TCP 66 12345 → 44156 [FIN, ACK] Seq=33 Ack=17 Win=65536 Len=0 TSval=2731439431 TSecr=2731439103Frame 61: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.647300754 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.647300754 seconds [Time delta from previous captured frame: 0.000234452 seconds] [Time delta from previous displayed frame: 0.280305849 seconds] [Time since reference or first frame: 7.390471256 seconds] Frame Number: 61 Frame Length: 66 bytes (528 bits) Capture Length: 66 bytes (528 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP SYN/FIN] [Coloring Rule String: tcp.flags & 0x02 || tcp.flags.fin == 1]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 12345, Dst Port: 44156, Seq: 33, Ack: 17, Len: 0# 四次挥手 4 Ack=34 Seq=17No. Time Source Destination Protocol Length Info 62 7.390499061 127.0.0.1 127.0.0.1 TCP 66 44156 → 12345 [ACK] Seq=17 Ack=34 Win=65536 Len=0 TSval=2731439431 TSecr=2731439431Frame 62: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface lo, id 0 Section number: 1 Interface id: 0 (lo) Encapsulation type: Ethernet (1) Arrival Time: Aug 29, 2023 08:26:32.647328559 EDT [Time shift for this packet: 0.000000000 seconds] Epoch Time: 1693311992.647328559 seconds [Time delta from previous captured frame: 0.000027805 seconds] [Time delta from previous displayed frame: 0.000027805 seconds] [Time since reference or first frame: 7.390499061 seconds] Frame Number: 62 Frame Length: 66 bytes (528 bits) Capture Length: 66 bytes (528 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP] [Coloring Rule String: tcp]Ethernet II, class="lazy" data-src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)Internet Protocol Version 4, class="lazy" data-src: 127.0.0.1, Dst: 127.0.0.1Transmission Control Protocol, class="lazy" data-src Port: 44156, Dst Port: 12345, Seq: 17, Ack: 34, Len: 0实例代码
HttpSampleClient
import java.io.BufferedReader;import java.io.InputStreamReader;import java.net.HttpURLConnection;import java.net.URL;public class HttpSampleClient { public static void main(String[] args) { try { URL url = new URL("http://localhost:8080"); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); int responseCode = connection.getResponseCode(); System.out.println("Response Code:" + responseCode); // read content BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream())); String line; StringBuilder response = new StringBuilder(); while ((line = reader.readLine()) != null) { response.append(line); } reader.close(); System.out.println("Response Body: " + response); connection.disconnect(); } catch (Exception e) { e.printStackTrace(); } }}HttpSampleServer
import com.sun.net.httpserver.HttpExchange;import com.sun.net.httpserver.HttpHandler;import com.sun.net.httpserver.HttpServer;import java.io.IOException;import java.io.OutputStream;import java.net.InetSocketAddress;public class HttpSampleServer { public static void main(String[] args) { try { // create http server to bind 8080 HttpServer server = HttpServer.create(new InetSocketAddress("127.0.0.1", 8080), 0); // bind path server.createContext("/", new MyHandler()); server.start(); System.out.println("Http Sever started on port 8080"); } catch (Exception e) { e.printStackTrace(); } } static class MyHandler implements HttpHandler { // 设置响应头c @Override public void handle(HttpExchange exchange) throws IOException { String response = "Hello from the local HTTP server!"; exchange.sendResponseHeaders(200, response.getBytes().length); // 获取输出流并写入响应内容 OutputStream os = exchange.getResponseBody(); os.write(response.getBytes()); os.close(); } }}HttpsSampleClient
import javax.net.ssl.*;import java.io.BufferedReader;import java.io.InputStreamReader;import java.io.PrintWriter;public class HttpsSampleClient { public static void main(String[] args) { try { // Create and configure the SSL context SSLContext sslContext = SSLContext.getInstance("TLS"); sslContext.init(null, new TrustManager[]{new X509TrustManager() { public java.security.cert.X509Certificate[] getAcceptedIssuers() { return null; } public void checkClientTrusted(java.security.cert.X509Certificate[] certs, String authType) { } public void checkServerTrusted(java.security.cert.X509Certificate[] certs, String authType) { } }}, new java.security.SecureRandom()); // Create an SSL socket SSLSocketFactory sslSocketFactory = sslContext.getSocketFactory(); SSLSocket socket = (SSLSocket) sslSocketFactory.createSocket("localhost", 12345); // Get input and output streams for secure communication BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream())); PrintWriter writer = new PrintWriter(socket.getOutputStream(), true); // autoFlush // Send a message to the server String message = "Hello, server!"; writer.println(message); // Read response from the server String serverResponse = reader.readLine(); System.out.println("Server response: " + serverResponse); // Close resources reader.close(); writer.close(); socket.close(); } catch (Exception e) { e.printStackTrace(); } }}HttpsSampleServer
import javax.net.ssl.*;import java.io.BufferedReader;import java.io.FileInputStream;import java.io.InputStreamReader;import java.io.PrintWriter;import java.security.KeyStore;public class HttpsSampleServer { public static void main(String[] args) { String keystorePath = "./keystore.jks"; char[] keystorePassword = "flannery".toCharArray(); try { // Load the keystore containing the server's SSL certificate KeyStore keystore = KeyStore.getInstance("JKS"); keystore.load(new FileInputStream(keystorePath), keystorePassword); // Create and configure the SSL context KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509"); kmf.init(keystore, keystorePassword); SSLContext sslContext = SSLContext.getInstance("TLS"); sslContext.init(kmf.getKeyManagers(), null, null); // Create an SSL server socket SSLServerSocketFactory sslServerSocketFactory = sslContext.getServerSocketFactory(); SSLServerSocket serverSocket = (SSLServerSocket) sslServerSocketFactory.createServerSocket(12345); System.out.println("Server listening on port 12345..."); // Wait for a client to connect SSLSocket clientSocket = (SSLSocket) serverSocket.accept(); System.out.println("Client connected: " + clientSocket.getInetAddress().getHostAddress()); // Get input and output streams for secure communication BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); PrintWriter writer = new PrintWriter(clientSocket.getOutputStream(), true); // autoFlush // Read data from client and respond String clientMessage; while ((clientMessage = reader.readLine()) != null) { System.out.println("Received from client: " + clientMessage); writer.println("Server received: " + clientMessage); } // Close resources reader.close(); writer.close(); clientSocket.close(); serverSocket.close(); } catch (Exception e) { e.printStackTrace(); } }}TcpSampleClient
import java.io.*;import java.net.Socket;public class TcpSampleClient { public static void main(String[] args) { try { // Create a socket to connect to the server Socket socket = new Socket("localhost", 12345); // Get input and output streams for the socket InputStream inputStream = socket.getInputStream(); OutputStream outputStream = socket.getOutputStream(); // Create readers and writers for easier communication BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream)); PrintWriter writer = new PrintWriter(outputStream, true); // autoFlush // Send a message to the server String message = "Hello, server!"; writer.println(message); // Read response from the server String serverResponse = reader.readLine(); System.out.println("Server response: " + serverResponse); // Close resources reader.close(); writer.close(); socket.close(); } catch (IOException e) { e.printStackTrace(); } }}TcpSampleServer
import java.io.*;import java.net.ServerSocket;import java.net.Socket;public class TcpSampleServer { public static void main(String[] args) { extracted(); } private static void extracted() { try { // Create a server socket ServerSocket serverSocket = new ServerSocket(12345); System.out.println("Server listening on port 12345..."); // Wait for a client to connect Socket clientSocket = serverSocket.accept(); System.out.println("Client connected: " + clientSocket.getInetAddress().getHostAddress()); // Get input and output streams for the socket InputStream inputStream = clientSocket.getInputStream(); OutputStream outputStream = clientSocket.getOutputStream(); // Create readers and writers for easier communication BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream)); PrintWriter writer = new PrintWriter(outputStream, true); // autoFlush // Read data from client and respond String clientMessage; while ((clientMessage = reader.readLine()) != null) { System.out.println("Received from client: " + clientMessage); writer.println("Server received: " + clientMessage); } // Close resources //reader.close(); //writer.close(); //clientSocket.close(); //serverSocket.close(); } catch (IOException e) { e.printStackTrace(); } }}UdpSampleClient
import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;public class UdpSampleClient {public static void main(String[] args) { try { DatagramSocket clientSocket = new DatagramSocket(); String message = "Hello, server!"; byte[] sendData = message.getBytes(); InetAddress serverAddress = InetAddress.getByName("localhost"); int serverPort = 12345; DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, serverAddress, serverPort); clientSocket.send(sendPacket); byte[] receiveData = new byte[1024]; DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length); clientSocket.receive(receivePacket); String serverResponse = new String(receivePacket.getData(), 0, receivePacket.getLength()); System.out.println("Server response: " + serverResponse); clientSocket.close(); } catch (IOException e) { e.printStackTrace(); } }}UdpSampleSever
import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;public class UdpSampleSever { public static void main(String[] args) { try { DatagramSocket serverSocket = new DatagramSocket(12345); System.out.println("Server listening on port 12345..."); byte[] receiveData = new byte[1024]; while (true) { DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length); serverSocket.receive(receivePacket); String clientMessage = new String(receivePacket.getData(), 0, receivePacket.getLength()); System.out.println("Received from client: " + clientMessage); InetAddress clientAddress = receivePacket.getAddress(); int clientPort = receivePacket.getPort(); String serverResponse = "Server received: " + clientMessage; byte[] sendData = serverResponse.getBytes(); DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, clientAddress, clientPort); serverSocket.send(sendPacket); } } catch (IOException e) { e.printStackTrace(); } }}资料
超详细的wireshark抓包使用教程
jks证书文件的生成步骤
如何使用wireshark抓取HTTPS数据包？
wireshark抓包分析HTTPS
Burp Suite的基本介绍及使用
渗透测试工具Burp Suite详解
vmware ctrl键粘滞的问题
wireshark过滤规则
Burp Suite HTTPS详解
来源地址：https://blog.csdn.net/AdrianAndroid/article/details/132568972
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