UDP Port 4500 – ipsec-nat-t

About UDP Port 4500

Port 4500 is registered with the Internet Assigned Numbers Authority (IANA) for ipsec-nat-t. The IANA description reads: ‘IPsec NAT-Traversal’. This port appears in 4 IDS rules and does not have notable malware activity indicators in our data.

IDS Rule References

4 IDS / security rules reference UDP port 4500. Presence in IDS rules does not mean traffic on this port is malicious. These are patterns security tools monitor.

Rule categories (top 2): attempted-recon (3), attempted-user (1).

Sample rule descriptions for UDP port 4500:

• SERVER-OTHER Cisco IOS Group-Prime memory disclosure exfiltration attempt
• SERVER-OTHER Cisco IOS Group-Prime MD5 memory disclosure attempt
• SERVER-OTHER Cisco IOS Group-Prime SHA memory disclosure attempt
• ET EXPLOIT IKEv2 Invalid Fragmented IKE_AUTH (CVE-2026-33824)

Data Sources

This information is compiled from: IANA Service Name and Transport Protocol Port Number Registry, Emerging Threats Open Ruleset (BSD 2-Clause / GPLv2 per SID range), and Snort Community Rules (GPLv2).