在Ruby中创建的简单服务器（TCPServer），如何从另一个IP访问？

Question

require 'socket'  # Provides TCPServer and TCPSocket classes

# Initialize a TCPServer object that will listen
# on localhost:2345 for incoming connections
server = TCPServer.new(2345)


loop do 
  # Wait until a client connects, then return a TCPSocket
  # that can be used in a similar fashion to other Ruby
  # I/O objects. (In fact, TCPSocket is a subclass of IO.)
  socket = server.accept

  socket.puts "What do you say?"

  they_said = socket.gets.chomp

  until they_said == "quit"
    socket.puts "You said: #{they_said}!"
    they_said = socket.gets.chomp
  end

  socket.puts "You said: #{they_said}. Goodbye!"

  # Close the socket, terminating the connection
  socket.close

  end

In above code I've created a simple server in ruby (a topic I've just been introduced to). As part of the exercise, I have following instruction:

"Connect to your pair's laptop from your laptop. You'll need the network IP address of the laptop with the server on it for this"

We were using telnet, but it looks like we can't use that with our Macs because it's not allowed on High Siera (at least without further configuration).

Can anyone suggest how we would do this, or point me in direction of material that will help?

Answer 1

If your OS does not accept connections then there is nothing you can do about it on the Ruby level. You will need to disable the Firewall or add an exception for this port.

Here are the three steps you'll need to take:

Make sure you bind the TCPServer to the "public" IP

Update: as @siegy22 pointed out in the comments: you can also use "0.0.0.0".

You can find it in the Network Preferences or through ipconfig

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
    ether ca:fe:ca:fe:ca:fe
    inet y.y.y.y netmask 0xffffff00 broadcast x.x.x.x
    media: autoselect
    status: active

Here yyyy is the IP you are interested in. Create the TCTServer like so:

TCPServer.new("y.y.y.y", 2345)

Stop the Firewall of your Mac (or allow specific connection to that Port)

This you can do in Preferences/Securiry Section.

RE-ENABLE it again after testing

Connect to the server from another computer

telnet y.y.y.y 2345

The above steps assume both computers are in the same Network, no connection through internet. Should you be on a different Network (eg bot connected to the internet) there are two solutions that come to my mind

1. Tunnel: Use a service such as ngrok ( https://ngrok.com/ ) to create a tunnel to your server with a public address. Follow the instructions and you will receive a public address that your peer can use to connect.
2. you could look up your public IP through a service (something like https://www.whatismyip.com/what-is-my-public-ip-address/ ) and then use this IP to connect. This might not work without further changes to your Network since your Router/Modem might/should block incoming connections and you would need to have some sort of forwarding to your Computer.

I suggest you try ngrok (or something similar) first.