1646
RADIUS Accounting (old)
Low RiskUDP — Security & VPN
Port Overview
Port Number
1646
Service Name
RADIUS Accounting (old)
Transport Protocol
UDP
Category
Security & VPN
Security Risk
Low
Port Range
Registered (1024-49151)
What is Port 1646?
Port 1646 is the legacy RADIUS accounting port, used before IANA standardized port 1813 for RADIUS accounting. It records network access session information such as duration, bytes transferred, and user identity. Many older RADIUS servers and network devices still support this port.
UDP
Security & VPN
Security Considerations
Port 1646 (RADIUS Accounting (old)) 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.