504
Citadel
Medium RiskTCP — Messaging
Port Overview
Port Number
504
Service Name
Citadel
Transport Protocol
TCP
Category
Messaging
Security Risk
Medium
Port Range
Well-Known (0-1023)
What is Port 504?
Port 504 is assigned to Citadel, an open-source groupware and messaging server providing email, calendaring, and bulletin board services.
TCP
Messaging
Security Considerations
Port 504 (Citadel) is classified as medium risk. While this service is commonly exposed, consider using encrypted alternatives where available.
Recommendation: Keep the service updated. Monitor logs for unusual activity.