For Norton Internet Security for Windows 2000: 3 rules are needed to get VisionGS to work with dynamic DNS update.

Rule 1:

Name: Webcam Software
Action: Permit
Direction: Inbound
Protocol: TCP

Application: C:\Program Files\VisionGS PE\visiongs.exe
Service: Any service for Remote Service; List of services (http and http-proxy) for Local Service
Address: Any address for Remote Address; Any address for Local Address

Rule 2:

Name: Webcam Software
Action: Permit
Direction: Inbound
Protocol: TCP

Application: C:\Program Files\VisionGS PE\visiongs.exe
Service: Any service for Remote Service; Single service (http) for Local Service
Address: Host address (your host name e.g., happycam.dyndns.tv) for Remote 
Address; Any address for Local Address

Rule 3:

Name: Webcam Software
Action: Permit
Direction: Outbound
Protocol: TCP

Application: C:\Program Files\VisionGS PE\visiongs.exe
Service: Single service (http) for Remote Service; Any service for Local Service
Address: Host address (e.g. members.dyndns.org) for Remote Address; Any address for Local Address