Whiteboard
Language note: Media and interface labels remain in their original language. Firewall domains and rules are preserved exactly.
Introduction
Section titled “Introduction”The Slingui Whiteboard uses a secure WebSocket connection (wss://slingui-whiteboard.com) for real-time collaboration between students and teachers. In environments with restrictive firewalls (such as schools and universities), the firewall must be configured to allow access to the Slingui Whiteboard WebSocket, hosted on tldraw’s architecture on Cloudflare, as described in this documentation.
Important: If you are not a network administrator, share this document with your institution’s IT department.
Why Do I Need to Allow Access Through the Firewall?
Section titled “Why Do I Need to Allow Access Through the Firewall?”Firewalls in educational environments often block WebSocket connections or restrict access to unfamiliar domains. This can cause the following whiteboard issues:
- ❌ Failure to connect to the whiteboard in real time
- ❌ Changes do not synchronize between users
- ❌ Error messages such as “Não foi possível se conectar ao servidor” (Unable to connect to the server) or “Conexão WebSocket fechada” (WebSocket connection closed)
- ❌ Incomplete loading of the whiteboard interface
What Needs to Be Allowed?
Section titled “What Needs to Be Allowed?”Domains (Allowlist)
Section titled “Domains (Allowlist)”Add the following domains to the firewall’s exception list:
wss://slingui-whiteboard.comslingui-whiteboard.com*.slingui-whiteboard.comslingui.comNote: The URL
wss://slingui-whiteboard.comis a secure WebSocket endpoint that runs over HTTPS and uses Cloudflare’s proxy. Make sure both the domain and its subdomains are allowed.
Ports (TCP)
Section titled “Ports (TCP)”Secure WebSocket (WSS) uses the same port as HTTPS:
| Protocol | Port | Purpose |
|---|---|---|
| TCP | 443 | Secure WebSocket connection (WSS) |
Important: Unlike AWS Chime, the whiteboard does not require UDP, only TCP on port 443.
For Teachers/Students (Without Firewall Access)
Section titled “For Teachers/Students (Without Firewall Access)”Send the following email to your IT department:
Subject: Request to allow firewall access for the Slingui.com collaborative whiteboard
Dear IT Department,
To use the Slingui.com collaborative whiteboard in our academic activities, we request that the following settings be allowed through the firewall:
Domains to allow (allowlist):
Section titled “Domains to allow (allowlist):”wss://slingui-whiteboard.comslingui-whiteboard.com*.slingui-whiteboard.comslingui.comcloudflare.com*.cloudflare.comPorts to allow:
Section titled “Ports to allow:”| Protocol | Port | Purpose |
|---|---|---|
| TCP | 443 | Secure WebSocket connection (WSS) |
These exceptions are essential for the collaborative whiteboard to work.
Thank you for your attention. We remain available for any clarification.
Kind regards,
[Your Name / Department]
[Educational Institution]