SCREENSY

                        Stef Gijsberts, Marijn van Wezel
                                August 2nd, 2021


Screensy is a simple screen sharing solution. Nothing more, nothing less.

It consists of two parts, the rendezvous part which runs on the server, and the
website part which runs in the user's browser. The rendezvous server is only
used for protocol negotiation and discovery of viewers. The video stream is
directly sent from the browser of the broadcaster to the browser of each
viewer. All traffic (between rendezvous and browser and between browsers) is
encrypted by default.

There are two ways to set up screensy. If you don't know which one to choose,
we recommend using Docker.


SERVER SETUP (WITH DOCKER)
--------------------------

1. Follow this guide to install Docker on your machine:

    https://docs.docker.com/engine/install/

2. Follow this guide to install Docker Compose on your machine:

    https://docs.docker.com/compose/install/

3. Clone this repository and navigate to it, using the following commands:

    git clone https://github.com/screensy/screensy.git
    cd screensy/

4. Change the first line of the included Caddyfile to your domain. For example
   if you want to host screensy on the domain "example.com", use this
   Caddyfile:

    example.com {
    	reverse_proxy website:80

    	@rendezvous {
    		header Connection *Upgrade*
    		header Upgrade websocket
    	}

    	reverse_proxy @rendezvous rendezvous:4000
    }

5. Change the value of the "external-ip" setting in the included
   "turnserver.conf" from "localhost" to your domain. For example if you want
   to host screensy on the domain "example.com", the first two lines of your
   "turnserver.conf" should look like this:

    # Set the value below to your public IP address or domain.
    external-ip=example.com

6. Make sure the required ports are accessible. We listed these ports at the
   bottom of this document. 

7. Start the Docker containers using Docker Compose, by running the following
   command:

    docker-compose up -d


SERVER SETUP (WITHOUT DOCKER)
-----------------------------

1.  Make sure you have the following software installed on your server:

     - NodeJS
     - A TypeScript compiler
     - A Go compiler
     - A reverse proxy that supports WebSocket (we recommend Caddy)
     - A STUN server (we recommend Coturn)
     - A TURN server (again, we recommend Coturn)

2.  Clone this repository and navigate to it, using the following commands:

     git clone https://github.com/screensy/screensy.git
     cd screensy/

3.  Install the required development dependencies for the rendezvous server,
    using the following command:

     cd screensy-rendezvous && npm install --only=development && cd ..

4.  Compile the TypeScript files in both the "screensy-rendezvous" as well as
    the "screensy-website" directory, using the following commands:

     cd screensy-rendezvous && tsc && cd ..
     cd screensy-website && tsc && cd ..

5.  Install the required dependencies for the webserver, using the following
    command:

     cd screensy-website && go get . && cd ..

6.  Make sure the required ports are accessible. We listed these ports at the
    bottom of this document.

7.  Start the webserver using the following command:

     cd screensy-website && go run main.go

    This starts the webserver on port 8080. We do not use the standard port
    "80" for this, as it will conflict with the reverse proxy we will set up in
    step 10.

8.  Set up the STUN and TURN server. Use the long-term credential mechanism
    with the username "screensy" and the password "screensy". We use the
    following "turnserver.conf" for this:

     external-ip=example.com
     listening-port=3478
     user=screensy:screensy
     lt-cred-mech
     realm=screensy

9.  Start the rendezvous server located in "screensy-rendezvous" directory,
    using the following commands:

     cd screensy-rendezvous
     npm install --only=production
     node server.js

    This starts a WebSocket server on port 4000.

10. Reverse proxy both the static file server and the rendezvous server. We use
    the following Caddyfile for this:

     example.com {
         reverse_proxy localhost:8080

         @rendezvous {
             header Connection *Upgrade*
             header Upgrade websocket
         }

         reverse_proxy @rendezvous localhost:4000
     }

    Keep in mind that most web browsers require HTTPS for WebRTC to work.


PORTS
-----

The following ports need to be accessible by the client for screensy to work.

+-------------+----------+-----------+
| Port number | Protocol | Service   |
+-------------+----------+-----------+
| 80          | TCP      | HTTP      |
| 443         | TCP      | HTTPS     |
| 3478        | TCP/UDP  | STUN/TURN |
| 49152-65535 | UDP      | TURN      |
+-------------+----------+-----------+