IPアドレスとポート番号の基本理解

import socket

# サーバーのIPアドレスとポート番号を指定
server_ip = '127.0.0.1'
server_port = 8080

# ソケットを作成
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    s.bind((server_ip, server_port))  # IPアドレスとポート番号でバインド
    s.listen()
    print(f"Server running on {server_ip}:{server_port}")
    conn, addr = s.accept()
    with conn:
        print('Connected by', addr)
        while True:
            data = conn.recv(1024)
            if not data:
                break
            conn.sendall(data)

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
        int port = 8080;

        TcpListener server = new TcpListener(ipAddress, port);
        server.Start();

        Console.WriteLine($"Server running on {ipAddress}:{port}");

        while (true)
        {
            TcpClient client = server.AcceptTcpClient();
            NetworkStream stream = client.GetStream();

            byte[] buffer = new byte[1024];
            int bytesRead = stream.Read(buffer, 0, buffer.Length);
            stream.Write(buffer, 0, bytesRead);
        }
    }
}

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

int main() {
    int server_fd = socket(AF_INET, SOCK_STREAM, 0);
    sockaddr_in address;
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = inet_addr("127.0.0.1");
    address.sin_port = htons(8080);

    bind(server_fd, (struct sockaddr*)&address, sizeof(address));
    listen(server_fd, 3);

    std::cout << "Server running on 127.0.0.1:8080" << std::endl;

    int client_fd = accept(server_fd, nullptr, nullptr);
    char buffer[1024] = {0};
    read(client_fd, buffer, 1024);
    send(client_fd, buffer, 1024, 0);
    close(client_fd);
    close(server_fd);
    return 0;
}

import java.io.*;
import java.net.*;

public class Server {
    public static void main(String[] args) throws IOException {
        String ip = "127.0.0.1";
        int port = 8080;

        ServerSocket serverSocket = new ServerSocket(port, 50, InetAddress.getByName(ip));
        System.out.println("Server running on " + ip + ":" + port);

        while (true) {
            Socket clientSocket = serverSocket.accept();
            BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
            String line;
            while ((line = in.readLine()) != null) {
                out.println(line);
            }
        }
    }
}

const net = require('net');

const server = net.createServer((socket) => {
  socket.on('data', (data) => {
    socket.write(data);
  });
});

const host = '127.0.0.1';
const port = 8080;

server.listen(port, host, () => {
  console.log(`Server running on ${host}:${port}`);
});