main里的可以，checkTcp里的没有
package main

import (
        "log"
        "net"
        "time"
)

func checkTcp(host string, timeout time.Duration) {
        conn, err := net.DialTimeout("tcp", host, 3*time.Second)
        if err != nil {
                log.Println("端口未打开:", err.Error())
        } else if conn != nil {

                log.Println("正常:", host)
        } else {
                log.Println("未知异常!")
        }
}

func main() {
        hostSlice := make([]string, 0)
        hostSlice = append(hostSlice, net.JoinHostPort("www.baidu.com", "80"))
        hostSlice = append(hostSlice, net.JoinHostPort("www.sina.com", "80"))
        for _, host := range hostSlice {
                log.Println(host)
                go checkTcp(host, 3*time.Second)
        }
}
--
FROM 221.219.185.*