Improve documentation for the TLS setup (#6)

* Update README.md

Add the TLS documentation

* Update README.md

The URL variable must point to the nginx proxy

* Update README.md

Add the TLS details and the usage with a TLS server

README.md

@@ -30,3 +30,66 @@ incoming shares (i.e. `tty-share` clients), and 5000 is the port of the web
 interface through which remote users can connect. You can override the
 defaults by specifying a different port mapping on the command line, e.g.
 `-p 7654:6543 -p 80:5000` to listen on `7654` and serve on `80`.
+
+
+## TLS Setup
+
+You'll need a certificate and the associed key file.
+Here is an example for a setup with `nginx` as proxy
+The idea is use nginx as
+  * reverse proxy for the web interface at port 5000 (listen at 443, terminate the TLS, and redirect to  localhost:5000)
+  * TLS endpoint at port 7654, and redirect to localhost:6543
+
+The client usage (after this TLS setup): `tty-share -server server:7654`  
+
+
+### nginx config for the web/browser side (http+websockets connection)
+This section can go for example in `/etc/nginx/site-enabled/default`
+
+    server {
+        server_name _;
+        listen 443 ssl default_server;
+        listen [::]:443 ssl default_server;
+        ssl_certificate /etc/ssl/certs/server.crt;
+        ssl_certificate_key /etc/ssl/private/server.key;
+        proxy_send_timeout 1600;
+        proxy_read_timeout 1600;
+        ########### tty-server application
+        # the /s/, /ws/ and /static/ locations - all used by the actual tty-server.
+        location / {
+                proxy_pass              http://localhost:5000;
+                proxy_redirect off;
+                proxy_set_header        Host $host;
+                proxy_set_header        X-Real-IP $remote_addr;
+                proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
+                proxy_set_header        X-Forwarded-Proto $scheme;
+
+                # Allow websocket upgrade
+                # https://iota.stackexchange.com/questions/2535/hornet-dashboard-not-working-the-client-is-not-using-the-websocket-protocol
+                proxy_set_header Upgrade $http_upgrade;
+                proxy_set_header Connection "Upgrade";
+        }
+    }
+
+### nginx config for the tty-share command line client (TLS connection)
+For the stream , you'll need the stream module from nginx. This configuration cannot go in the `site-enabled/` because it's limited to the http module and not the stream module. Store it in `/etc/nginx/modules-enabled/99-tty-server-stream.conf`, for example
+
+    stream {
+        server {
+            # https://nginx.org/en/docs/stream/ngx_stream_core_module.html#server
+            # the tty-server tcp connection ssl proxy
+            listen 7654 ssl so_keepalive=30m::10;
+            proxy_pass localhost:6543;
+            ssl_certificate /etc/ssl/certs/server.crt;
+            ssl_certificate_key /etc/ssl/private/server.key;
+        }
+    }
+
+You'll have to adapt the URL variable to use the nginx URL:
+
+    docker run \
+      -p 6543:6543 -p 5000:5000 \
+      -e URL=https://server.domain.com \
+      --cap-drop=all --rm \
+      tty-server
+