嗨！！！

在这个工具的帮助下，我设法将3000端口转发。https://www.yougetsignal.com/tools/open-ports/

我之所以转发这个端口，是因为我有一个聊天应用程序，我做的它在本地主机上运行得非常好。可悲的是，当我让我的朋友打开我的web聊天应用程序（http://mywebsite.com:81/chat/)时，javascript并没有通过3000端口连接到我的服务器上。。。

下面是我的一些代码:

server.js

const io = require('socket.io')(3000)

const users = {}

io.on('connection', socket => {
    // On message receive
    socket.on('msg', message => {
        //broadcast message
        socket.broadcast.emit('msg', {name: users[socket.id], msg: message});

        // If message starts with "/" AKA is a command
        if(message.startsWith("/")){
            message=message.split(" ");
            //message[0]= /help

            if(message[0] == "/say"){
                txt=message.splice(1).join(" "); // GET TEXT AFTER /help
                socket.emit('msg', {name: "TomatoBot", msg: txt});
            }else if(message[0] == "/help"){
                txt=message.splice(1).join(" "); // GET TEXT AFTER /help
                socket.emit('msg', {name: "TomatoBot", msg: "help dialog"});
            }else if(message[0] == "/list"){
                socket.emit('msg', {name: "TomatoBot", msg: users[socket.id]+" connected users:\n"});
            }else{
                //no commands found, throw error
                socket.emit('msg', {name: "TomatoBot", msg: "@"+users[socket.id]+"\nUnknown command: "+message[0]+". Type /help for a list of commands."});
            }
        }
    })

    // On user join
    socket.on('new', name => {
        users[socket.id] = name;
        socket.broadcast.emit('new', name);
    })

    // On user disconnect
    socket.on('disconnect', () => {
        socket.broadcast.emit('bye', users[socket.id]);
        delete users[socket.id];
    })
})

script.js（我的客户端脚本）

const socket = io(':3000'); // go from localhost:81 to localhost:3000!!
const form = document.getElementById('form');
const input = document.getElementById('input');
const msgbox = document.getElementById('msgbox');

const name = prompt('name?');
socket.emit('new', name);
appendMessage(name+' joined');
// etc etc.....

因此，正如我已经说过的，连接和消息在本地主机上通过，但只要我使用外部域/IP，就什么都不起作用了！！当从外部世界直接访问mywebsite.org:3000/socket.io/socket.io.js时，连接是有效的！！

我很迷路，一定是因为我的代码中有个愚蠢的错误。

谢谢大家的帮助！！