MTU

import socket
import struct
import time

def probe_mtu(target_ip, start_mtu=1480, end_mtu=1580):
    for mtu in range(start_mtu, end_mtu):
        # 创建UDP套接字
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        # 设置UDP数据包的大小
        sock.setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, mtu)

        try:
            # 发送一个只有几个字节的数据包
            sent_time = time.time()
            sock.sendto(b'X' * mtu, (target_ip, 33434))

            # 设置超时时间
            sock.settimeout(3)

            # 尝试接收数据，如果在超时时间内收到ICMP错误回应，则表明MTU值是正确的
            try:
                sock.recvfrom(1)
            except socket.timeout:
                print(f"Probe MTU: {mtu} succeeded")
                return mtu
            except socket.error as e:
                # 如果接收到其他错误，则可能是MTU值正确
                print(f"Probe MTU: {mtu} failed with error {e}")
                return mtu
        except socket.error as e:
            # 如果发送失败，则可能是MTU值太小
            print(f"Probe MTU: {mtu} failed with error {e}")

        finally:
            sock.close()

# 使用示例
target_ip = "223.5.5.5"  # 替换为目标设备的IP地址
mtu_value = probe_mtu(target_ip)
print(f"Estimated MTU of {target_ip} is {mtu_value} bytes.")