在 Ubuntu 下進行 C++ 網絡編程實戰，你需要了解一些基本的網絡編程概念和相關庫

1. 安裝必要的庫和工具：

sudo apt-get update
sudo apt-get install build-essential g++ cmake

2. 創建一個新的項目文件夾并進入：

mkdir cpp_networking_project
cd cpp_networking_project

3. 創建一個名為 CMakeLists.txt 的文件，用于配置項目：

cmake_minimum_required(VERSION 3.10)
project(cpp_networking_project)

set(CMAKE_CXX_STANDARD 14)

add_executable(server server.cpp)
add_executable(client client.cpp)

4. 創建服務器（server.cpp）和客戶端（client.cpp）源代碼文件：

server.cpp:

#include<iostream>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <cstring>

const int PORT = 8080;
const int BUFFER_SIZE = 1024;

int main() {
    int server_fd, new_socket;
    struct sockaddr_in address;
    int addrlen = sizeof(address);
    char buffer[BUFFER_SIZE] = {0};
    char *message = "Hello from server!";

    // 創建 socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        std::cerr << "Socket creation failed"<< std::endl;
        return -1;
    }

    // 綁定 socket
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        std::cerr << "Bind failed"<< std::endl;
        return -1;
    }

    // 監聽連接
    if (listen(server_fd, 3) < 0) {
        std::cerr << "Listen failed"<< std::endl;
        return -1;
    }

    // 接受連接
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t *)&addrlen)) < 0) {
        std::cerr << "Accept failed"<< std::endl;
        return -1;
    }

    // 讀取客戶端發送的數據
    read(new_socket, buffer, BUFFER_SIZE);
    std::cout << "Message from client: "<< buffer<< std::endl;

    // 向客戶端發送消息
    send(new_socket, message, strlen(message), 0);
    std::cout << "Message sent to client"<< std::endl;

    // 關閉 socket
    close(new_socket);
    close(server_fd);

    return 0;
}

client.cpp:

#include<iostream>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <cstring>

const std::string SERVER_IP = "127.0.0.1";
const int PORT = 8080;
const int BUFFER_SIZE = 1024;

int main() {
    int sock = 0;
    struct sockaddr_in serv_addr;
    char buffer[BUFFER_SIZE] = {0};
    char *message = "Hello from client!";

    // 創建 socket
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        std::cerr << "Socket creation failed"<< std::endl;
        return -1;
    }

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);

    // 將 IP 地址轉換為二進制格式
    if (inet_pton(AF_INET, SERVER_IP.c_str(), &serv_addr.sin_addr) <= 0) {
        std::cerr << "Invalid address / Address not supported"<< std::endl;
        return -1;
    }

    // 連接到服務器
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        std::cerr << "Connection failed"<< std::endl;
        return -1;
    }

    // 向服務器發送消息
    send(sock, message, strlen(message), 0);

    // 從服務器接收消息
    read(sock, buffer, BUFFER_SIZE);
    std::cout << "Message from server: "<< buffer<< std::endl;

    // 關閉 socket
    close(sock);

    return 0;
}

5. 編譯并運行項目：

cmake .
make
./server &
./client

這個例子展示了如何在 Ubuntu 下使用 C++ 進行基本的網絡編程。你可以根據自己的需求修改代碼，實現更復雜的功能。