Should port 1646 be open on my firewall?

Port 1646 is generally safe to have open. Apply standard security practices: keep software updated and monitor access logs.

What transport protocol does port 1646 use?

Port 1646 (RADIUS Accounting (old)) uses the UDP transport protocol and falls under the Security & VPN category.

:1646 (UDP)

RADIUS Accounting (old)

Q: Is port 1646 (RADIUS Accounting (old)) dangerous?

Port 1646 is classified as low risk. This service uses encryption or has a minimal attack surface, making it relatively safe to expose with standard security practices.

Low Risk

UDP — 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.

Related Ports — Security & VPN

31 MSG-AUTH 48 Auditd 49 TACACS 56 XNS-AUTH 62 ACA Services 65 TACACS-DS 88 Kerberos 90 DNSIX Security

Related Terms

SSL/TLS Certificate DDoS DNS Spoofing Encryption Firewall HTTPS