go实现测试端口是否打开

package main

import (
	"fmt"
	"net"
	"time"
)

func checkUDPPort(address string, timeout time.Duration) (bool, time.Duration) {
	var conn net.Conn
	var err error
	start := time.Now()
	conn, err = net.DialTimeout("udp", address, timeout)

	if err != nil {
		// fmt.Println("DialTimeout error:", err)
		return false, time.Since(start)
	}
	defer conn.Close()

	// Send a message to the server
	_, err = conn.Write([]byte("Hello, World!"))
	if err != nil {
		// fmt.Println("Write error:", err)
		return false, time.Since(start)
	}

	// Set a deadline for reading
	conn.SetReadDeadline(time.Now().Add(timeout))

	// Try to read from the server
	buf := make([]byte, 1024)
	_, err = conn.Read(buf)
	if err != nil {
		// fmt.Println("Read error:", err)
		return false, time.Since(start)
	}
	return true, time.Since(start)
}

// checkPort 检测端口是否开放
func checkTCPPort(address string, timeout time.Duration) (bool, time.Duration) {
	start := time.Now()
	conn, err := net.DialTimeout("tcp", address, timeout)
	if err != nil {
		// fmt.Println(err)
		return false, time.Since(start)
	}
	conn.Close()
	return true, time.Since(start)
}

func main() {
	ports := []int{22, 23, 53, 80, 443, 10080, 3306, 25}
	addr := "192.168.140.3"
	timeout := 1 * time.Second

	for _, port := range ports {
		address := fmt.Sprintf("%s:%d", addr, port)

		// 检测TCP端口
		isOpen, duration := checkTCPPort(address, timeout)
		fmt.Printf("TCP %s open: %t (checked in %s)\n", address, isOpen, duration)
	}
	for _, port := range ports {
		address := fmt.Sprintf("%s:%d", addr, port)

		// 检测UDP端口
		isOpen, duration := checkUDPPort(address, timeout)
		fmt.Printf("UDP %s open: %t (checked in %s)\n", address, isOpen, duration)
	}
}

注意：

由于UDP协议的无连接特性，单纯发送数据包并等待响应可能无法判断端口是否开放。

许多UDP服务不会响应任何的UDP数据包，而只有在收到特定格式的数据包后才会响应。

可以使用UDP探测工具，例如Nmap，这样的工具能够更好地检测UDP端口的状态。