Network Requirements

Competition Control runs on one host computer at the venue. Client devices connect to it over the local network, and the host computer reaches the internet only to sign in and install updates. This page lists what the network needs so you can share it with the venue or your IT department ahead of time.

The short version: client devices must be able to reach the host computer over plain HTTP on the local network, and the host computer needs outbound HTTPS to a small set of RECF and Microsoft addresses. Nothing needs to reach the host computer from the internet.

Local Network

The host computer and every client device must be on the same local network, and that network must allow devices to talk to each other. Client devices never need internet access.

Requirement	Details
Protocol	HTTP and WebSocket over TCP, unencrypted. Client devices open the host computer's address with `http://`. The host computer also serves `https://` with a certificate it signs itself, which only browser devices that drive field controllers need (see below).
Host computer ports	TCP 80 and TCP 53243, plus TCP 443 and TCP 53244 for `https://`, inbound from the local network. The host computer listens on the well-known ports when it can (see below).
Device to device traffic	Must be allowed. Many school, hotel, and conference networks enable "client isolation" or "AP isolation" on Wi-Fi, which blocks exactly this. Ask for it to be turned off for the network you will use, or bring your own.
Discovery	UDP 5353 (mDNS) on the local network. Optional. It lets a second host computer find the event by name in the launcher. Everything still works without it if you type the address.
Addressing	The host computer should keep the same IP address for the whole event. Ask for a DHCP reservation or set a static address. If the address changes, every client device has to reconnect using the new one.
Wired connection	Recommended for the host computer when the venue offers one. It removes the most common source of dropped connections.

Which Port Client Devices Use

When the host computer starts an event, it listens on TCP 80 if that port is free and always on TCP 53243. Port 80 is the standard web port, so when it is available the Server address on the Devices page has no port number at all, for example http://192.168.1.20. Client devices can type just the IP address.

If something else on the host computer already uses port 80 (a web server, some printer software, or another copy of Competition Control), the address includes the fallback port instead, for example http://192.168.1.20:53243. Type the address exactly as the Devices page shows it. The QR code shown on a new client device and the kiosk URL for each display group always use whichever address is correct.

Allow both ports through the host computer's firewall so either one works. On Windows, choose to allow access if a firewall prompt appears the first time an event starts.

The Secure Address

The host computer also listens for https:// on TCP 443 when that port is free, and otherwise on TCP 53244. Only one kind of device needs it: a laptop that drives an OpenFC field controller from Chrome or Edge instead of the desktop app, because browsers allow serial ports only from a secure address. The Field Controllers page links to this address when it is opened over plain http://. The certificate is signed by the host computer itself, so the browser warns once and remembers the choice; every other device keeps using the plain http:// address.

If the Venue Network Does Not Cooperate

Bring a travel router or use a phone hotspot, and connect the host computer and every client device to it. A dedicated router is the most reliable option because it keeps the event traffic away from the venue's guest network, and the host computer's address does not change. Client devices do not need internet, so the router does not need an uplink. If the host computer has to sign in or update, connect it to a network with internet first, then move it to the event network.

Internet Access

Only the host computer needs internet access, and only at specific times. Once an event is open it runs fully offline.

When	What needs internet
Before the event	Download the installer, sign in with an RECF account, and install updates.
During the event	Nothing. Scoring, displays, rankings, and reports all run on the local network.
After the event	Publishing results to RECF, when that feature becomes available.

Addresses and Ports

Give this list to the IT department if the venue filters outbound traffic. All connections are outbound from the host computer over HTTPS on TCP 443. No inbound connections from the internet are needed.

Address	Purpose
`c2.recf.org`	The download page, this documentation, and the legal documents linked from the launcher.
`recf-competitioncontrol-prd-api.azurewebsites.net`	The RECF release service. The launcher checks it for updates and downloads the installer from it.
`*.ciamlogin.com`	RECF account sign in. The launcher opens this in your browser and then exchanges the result for a session.
`*.blob.core.windows.net`	Microsoft Azure storage. Installer and update downloads redirect here.

Sign in also uses a temporary connection on the host computer itself: the launcher listens on a random port bound to 127.0.0.1 so the browser can hand the result back. This never leaves the machine and needs no firewall rule.

Note
The exact address list can change between versions. When it does, the changelog will say so.

Summary for IT

Copy this into your venue request.

One host computer on the venue network needs a fixed IP address and inbound TCP 80, 443, 53243, and 53244 from other devices on the same network.
Client isolation must be off on the Wi-Fi network the event uses so tablets and displays can reach the host computer.
Client devices need no internet access.
The host computer needs outbound HTTPS (TCP 443) to c2.recf.org, recf-competitioncontrol-prd-api.azurewebsites.net, *.ciamlogin.com, and *.blob.core.windows.net before the event to sign in and update. It needs no internet during the event.
Optional: allow mDNS (UDP 5353) on the local network so the launcher can find the host computer by name.

Host Computer Setup for installing and signing in.
Client Devices for connecting tablets and laptops.
Troubleshooting for the messages devices show when they lose the connection.