网络协议分析-http/https/tcp/udp

赵健zj2023-08-30 11:01

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

bash 复制代码 
# 三次握手:SYN=1 Seq=0
No.     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=128

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 44156, Dst Port: 12345, Seq: 0, Len: 0

# 三次握手:SYN1 ACK=1 Seq=0
No.     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=128

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 12345, Dst Port: 44156, Seq: 0, Ack: 1, Len: 0

# 三次握手:Ack=1 Seq=1
No.     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=2731439096

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, 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=2731439096

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 44156, Dst Port: 12345, Seq: 1, Ack: 1, Len: 15
Data (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=2731439098

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, 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=2731439098

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 12345, Dst Port: 44156, Seq: 1, Ack: 16, Len: 32
Data (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=2731439100

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 44156, Dst Port: 12345, Seq: 16, Ack: 33, Len: 0

# 四次挥手 1 FIN=1 Ack=33 Seq=16
No.     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=2731439100

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 44156, Dst Port: 12345, Seq: 16, Ack: 33, Len: 0

# 四次挥手 2 ACK=17 Seq=33
No.     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=2731439103

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 12345, Dst Port: 44156, Seq: 33, Ack: 17, Len: 0

# 四次挥手: 3 Fin=1 Ack=17 Seq=33
No.     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=2731439103

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 12345, Dst Port: 44156, Seq: 33, Ack: 17, Len: 0

# 四次挥手 4 Ack=34 Seq=17
No.     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=2731439431

Frame 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, 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, Src: 127.0.0.1, Dst: 127.0.0.1
Transmission Control Protocol, Src Port: 44156, Dst Port: 12345, Seq: 17, Ack: 34, Len: 0

实例代码

HttpSampleClient

java 复制代码 
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

java 复制代码 
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

java 复制代码 
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

java 复制代码 
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

bash 复制代码 
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

bash 复制代码 
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

bash 复制代码 
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

bash 复制代码 
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

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