Networking

Participants join by opening an address on their phone, from the QR code or the join link. This page makes sure the right address is offered, then lists every connection the server makes to the outside.

The invitation address

In the lobby, the host’s console offers addresses under Invitation address:

• APP_PUBLIC_URL, first, when it is set;
• the server’s local network addresses: HOST_LAN_IPS when it is set, otherwise the addresses the application sees on its own network interfaces, Docker bridge addresses left out;
• the address of the page the console is open on;
• Other address…, to type any address.

The address chosen is kept for the game (the console, the projection and the share link agree), frozen once the game starts, and remembered by the browser for the next one.

What to configure, per setup

Setup	What the console offers by itself	Configure
A server with a domain name, behind a reverse proxy	The page’s address, which is the public one	APP_PUBLIC_URL=https://quiz.example.org to offer it first
Docker Desktop on a Mac or a PC	No local address: Docker’s virtual machine hides the computer’s network	HOST_LAN_IPS=192.168.1.20 (the computer’s address, from its network settings)
Linux server, the shipped Compose file or the standalone container with -p	No local address: the container sits on a Docker bridge network	HOST_LAN_IPS=192.168.1.20
Linux server, container on the host network (--network host)	The server’s local addresses, detected	Nothing, or HOST_LAN_IPS to offer only one
Console opened on localhost	“This page” is useless to phones: the console opens its help and preselects a local address when it knows one	One of the above

HOST_LAN_IPS takes bare IPv4 addresses, separated by commas. The console adds the scheme and the port of the page it is open on.

Both variables can also be set from Administration → Settings (level C3, applied at once).

Test it from a phone

The setup wizard and Administration → Health offer a phone test for each invitation address: a QR code to scan with a phone on the participants’ network. The page records which addresses a phone actually reached, and from Health an administrator makes a reached one the instance’s invitation address (APP_PUBLIC_URL). See Health.

When phones cannot reach it

• Same network. Phones must be on a network that routes to the server. A guest Wi-Fi often isolates its clients from the rest of the network.
• Firewall. The server’s firewall must let the published port through (HTTP_PORT, 18080 by default).
• HTTPS page, HTTP address. When the console is served over HTTPS, an http:// local address shows a warning on phones. A public address with a certificate avoids it.

Outgoing connections

The complete list of connections the server opens to the outside:

Connection	When	What the other side sees	Turn it off
Update check, to api.github.com	On by default. At most once a day (once an hour after a failure), only when an administration page, qd version or ./quizdock status asks	The server’s IP address and a QuizDock/<version> user agent	UPDATE_CHECK=false, or the quick setup’s offline answer
Community catalogue	Off by default. Only when QUIZ_STORE_URL is set, to the hosts it and QUIZ_STORE_HOSTS allow	The server’s IP address; no account, quiz or result is sent	Leave QUIZ_STORE_URL empty
Your OpenID Connect provider	OIDC mode only: discovery, tokens, keys	What sign-in requires	It can be on your internal network

Nothing else: no telemetry, no e-mail, no webhooks.

Outside the running server:

• The ./quizdock script downloads its files from raw.githubusercontent.com (at init), and Docker pulls the images from Docker Hub (at up and upgrade).
• Browsers, not the server, follow the links to free media libraries in the editor (MEDIA_LIBRARY_LINKS), the feedback links on the home page (APP_FEEDBACK_URL), and load the images a quiz’s text points to on the web.

A server with no Internet access at all: see Air-gapped installation.