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BAS Techs: Stop Guessing On Ports

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Purple Flower

Your quick port cheat sheet for Niagara, Distech, Tosi, Honeywell + JCI.

Why it Matters: When controllers won’t discover, stations won’t sync, or tools won’t connect… it’s almost always a port problem.

This is your fast reference.

Niagara 4 | Tosi | Distech | Honeywell | Johnson Controls

Niagara 4 (secure by design) - Prioritizes Secure Communication & Access:


  • TCP 443 (HTTPS/Fox over WS): For secure web access and communication that bypasses network restrictions.
  • TCP 4911 (Fox S): The default for secure Fox protocol (Workbench/Station-to-Station).
  • TCP 5011 (Platform TLS): Used for secure platform connections from Workbench to the station/JACE.

View the latest Niagara Hardening Guide can be found here.

Tosi Lock (Secure Access Gate): The Tosi lock handles initial and secure data connections:


  • 80/8000: Used for initial connections and general communication.
  • 443: Crucial for secure data transmission within the VPN tunnel.

Security Note: The Tosi lock's inbound port must be open for these ports plus any ports used by devices below it in the network hierarchy.

Heads up: Inbound port on Tosi must be open for these plus anything downstream.

Distech Controllers (Discovery & Services) - Distech controllers use ports for synchronization, discovery, and external services:


  • 123 (UDP - NTP): Sets the controller's real-time clock.
  • 53 (UDP/TCP - DNS): Provides URL name lookup.
  • 443 (TCP): Connects to Weather Service and the Licensing Server.
  • 5353 (UDP - mDNS): Enables controller discovery on the network.

View the full Distech Controllers list here.

Honeywell Controllers (Core Protocols & Web)- Honeywell devices support standard BAS and web protocols:


  • 47808 (UDP - BACnet/IP): The industry standard port for BACnet/IP communication.
  • 502 (TCP - Modbus/TCP): Used for Modbus/TCP network communication.
  • 80/443 (TCP - HTTP/S): For accessing embedded web servers for configuration.

Johnson Controls CCT (Database):


  • TCP 1433 (SQL Server): Essential for CCT to connect to its local or network SQL database for configuration data.

Bottom line: Ports matter. If you can’t connect… start here.

Need help? Stromquist can help techs troubleshoot, explain port dependencies, and verify what needs to be opened — for Niagara, Distech, Honeywell, Tosi, JCI and more.


Talk to Stromquist

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