新人求助！golang 怎么实现服务器被外网访问

我按照gopl上写了一个聊天服务器程序，想运行在阿里云服务器上，阿里云服务器能跑nginx，设置应该没问题

代码如下

package main 

import(
    "fmt"
    "net"
    "log"
    "bufio"
)



type client chan<- string

var(
    entering = make(chan client)
    leave = make(chan client)
    messages = make(chan string)    
)

func main(){
    listenner, err := net.Listen("tcp", "120.78.169.107:8000")
    if err != nil{
        log.Fatal(err)
    }
    go broadcaster()
    for {
        conn, err := listenner.Accept()
        if err != nil{
            log.Print(err)
            continue
        }
        go handleConn(conn)
    }
}

func broadcaster(){
    clients := make(map[client] bool)
    for{
        select{
        case msg := <-messages:
            for cli := range clients{
                go func (cli client, msg string){
                    cli <- msg
                }(cli, msg)
            }
        case cli := <-entering:
            clients[cli] = true
        case cli := <-leave:
            delete(clients, cli)
            close(cli)
        }
    }
}

func handleConn(c net.Conn){
    ch := make(chan string)
    go clientWrite(c, ch)

    who := c.RemoteAddr().String()
    ch <- "Please input your name:"
    name := bufio.NewScanner(c)
    name.Scan()
    who = name.Text()
    ch <- "You are " + who
    entering <- ch
    messages <- who + " has arrived"
    input := bufio.NewScanner(c)
    for input.Scan(){
        messages <- who + ": " + input.Text()
    }

    messages <- who + " has left"
    leave <- ch
    c.Close()
}

func clientWrite(c net.Conn, ch  <-chan string){
    for msg := range ch{
        fmt.Fprintf(c, "\t%s\n", msg)
    }
}