Is port 1645 (RADIUS Authentication (old)) dangerous?

Port 1645 is classified as medium risk. It is commonly exposed but consider using encrypted alternatives where available and monitor activity.

Should port 1645 be open on my firewall?

Port 1645 can be open but should be monitored closely. Keep the service updated and prefer encrypted alternatives where available.

What transport protocol does port 1645 use?

Port 1645 (RADIUS Authentication (old)) uses the UDP transport protocol and falls under the Security & VPN category.

:1645 (UDP)

RADIUS Authentication (old)

Medium Risk

UDP — Security & VPN

Port Overview

Port Number 1645

Service Name RADIUS Authentication (old)

Transport Protocol UDP

Category Security & VPN

Security Risk Medium

Port Range Registered (1024-49151)

What is Port 1645?

Port 1645 is an older, unofficial RADIUS authentication port used before the IANA officially assigned port 1812. Some legacy network devices and AAA servers still use this port for authentication. Network engineers managing older infrastructure may need to support both ports 1645 and 1812 simultaneously.

UDP Security & VPN

Security Considerations

Port 1645 (RADIUS Authentication (old)) 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.

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