Python--网络编程

3. 网络编程与Socket

3.1 Socket基础

创建Socket

import socket# TCP Socket
tcp_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)# UDP Socket
udp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

服务器端函数

函数	描述
​bind((host, port))​	绑定地址和端口
​listen(backlog)​	开始监听传入连接
​accept()​	接受连接，返回新Socket和客户端地址

客户端函数

函数	描述
​connect((host, port))​	连接到服务器
​send(data)​	发送数据（TCP）
​sendto(data, address)​	发送数据（UDP）

3.2 高级Socket功能

超时与异常处理

import sockets = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.settimeout(5)  # 设置超时为5秒
try:s.connect(("example.com", 80))
except socket.timeout:print("连接超时！")
except socket.error as e:print(f"连接错误: {e}")
finally:s.close()

多线程Socket服务器

import socket
import threadingdef handle_client(conn, addr):print(f"客户端 {addr} 已连接")data = conn.recv(1024)conn.send(b"Server: Received")conn.close()server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(("0.0.0.0", 8080))
server.listen(5)while True:conn, addr = server.accept()thread = threading.Thread(target=handle_client, args=(conn, addr))thread.start()

实现简单HTTP请求

# 发送HTTP GET请求
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("example.com", 80))
s.send(b"GET / HTTP/1.1\r\nHost: example.com\r\n\r\n")
response = s.recv(4096)
print(response.decode())
s.close()

3.3 TCP通信示例

服务器端：

server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.bind(("0.0.0.0", 8080))
server_socket.listen(5)
conn, addr = server_socket.accept()
data = conn.recv(1024)
conn.send(b"Received")
conn.close()

客户端：

client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client_socket.connect(("127.0.0.1", 8080))
client_socket.send(b"Hello Server")
response = client_socket.recv(1024)
client_socket.close()

3.4 UDP通信示例

服务器端：

udp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
udp_socket.bind(("0.0.0.0", 9090))
data, addr = udp_socket.recvfrom(1024)
udp_socket.sendto(b"ACK", addr)

客户端：

udp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
udp_socket.sendto(b"Hello", ("127.0.0.1", 9090))
response, addr = udp_socket.recvfrom(1024)

3.5 端口扫描与主机探测

使用 python-nmap​ 库进行端口扫描：

import nmapscanner = nmap.PortScanner()
scanner.scan("192.168.1.1", "1-1024", "-sS")  # SYN扫描
print(scanner.all_hosts())
print(scanner["192.168.1.1"].all_tcp())

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4. 工具与资源

• 正则表达式在线测试工具：https://regex101.com

• 网络调试工具：Wireshark、Postman、tcpdump

• Python库：

  • ​python-nmap​：pip install python-nmap​

  • ​requests​：HTTP请求库

  • scapy：构造和解析网络数据包。

    pip install scapy
    

  • asyncio：实现异步网络编程。

    import asyncioasync def tcp_echo_client(message):reader, writer = await asyncio.open_connection("127.0.0.1", 8888)writer.write(message.encode())data = await reader.read(100)print(f"Received: {data.decode()}")writer.close()asyncio.run(tcp_echo_client("Hello Server"))