Port 1812 — RADIUS auth
Quick reference for TCP/UDP port 1812, used by RADIUS auth. Includes what the service does, security guidance and related ports.
What is port 1812?
RADIUS authentication.
What port does RADIUS auth use?
RADIUS auth listens on port 1812 by default.
Is port 1812 open? How to check
Run one of these from your computer, replacing HOST with the IP address or domain you want to test.
nc -zvu HOST 1812
Test-NetConnection HOST -Port 1812
nmap -sU -p 1812 HOST
A refused or timed-out connection means the port is closed or filtered by a firewall.
Security guidance
Medium risk — open with care
Port 1812 (RADIUS auth) can safely face the internet if you keep the software up to date, restrict admin endpoints, and use TLS where possible. Audit who can reach it and watch your logs.
Related ports
Frequently asked
What is port 1812 used for?+
Port 1812 is the standard TCP/UDP port for RADIUS auth. RADIUS authentication.
What port does RADIUS auth use?+
RADIUS auth listens on port 1812 by default.
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