RADIUS Accounting
What is Port 1813?
Port 1813 is the standard port for RADIUS accounting messages, defined in RFC 2866. While port 1812 handles authentication, port 1813 receives accounting records that track user session information — login time, logout time, data transferred, session duration, and other usage metrics. Network access servers send Accounting-Start records when a user session begins and Accounting-Stop records when it ends, with optional Interim-Update records during long sessions. This data is essential for ISP billing, network usage auditing, compliance reporting, and capacity planning. RADIUS accounting records are typically stored in databases or log files for analysis and reporting.
Common Uses
- ISP usage billing and subscriber tracking
- Network access logging and compliance auditing
- Wi-Fi usage statistics and reporting
- VPN session duration and bandwidth tracking
Technical Details
Copy-paste commands to check port 1813 (RADIUS Accounting) from your terminal
Test connectivity
nmap -p 1813 -sU -sV example.com
(echo > /dev/tcp/example.com/1813) 2>/dev/null && echo "open" || echo "closed"
Open port in firewall
sudo ufw allow 1813/udp
sudo iptables -A INPUT -p udp --dport 1813 -j ACCEPT
sudo firewall-cmd --permanent --add-port=1813/udp && sudo firewall-cmd --reload
Security Considerations
RADIUS accounting data should be protected as it reveals user activity patterns. Use the same security measures as authentication — strong shared secrets, encrypted transport, and access restrictions. Ensure accounting logs are tamper-proof for compliance. Implement log integrity monitoring and backup accounting records regularly.
Popular Ports Reference
The most commonly used and referenced network ports