991
NAS
Low RiskTCP/UDP — Other
Port Overview
Port Number
991
Service Name
NAS
Transport Protocol
TCP/UDP
Category
Other
Security Risk
Low
Port Range
Well-Known (0-1023)
What is Port 991?
Netnews Administration System (NAS), defined in RFC 4707, for centralized management of NNTP news server configurations. Usenet has significantly declined.
TCP/UDP
Other
Security Considerations
Port 991 (NAS) is classified as low risk. This service uses encryption or has a minimal attack surface, making it relatively safe to expose.
Recommendation: Standard security practices apply. Keep software updated and monitor access.