UDP Port 139 – NetBIOS Session Service (SMB over NetBIOS)

About UDP Port 139

The Internet Assigned Numbers Authority (IANA) registers port 139 for netbios-ssn. The IANA description reads: ‘NETBIOS Session Service’. This port appears in 1 IDS rule and does not have notable malware activity indicators in our data.

IDS Rule References

1 IDS / security rule reference UDP port 139. Presence in IDS rules does not mean traffic on this port is malicious. These are patterns security tools monitor.

Rule categories (top 1): attempted-recon (1).

Sample rule descriptions for UDP port 139:

• ET SCAN Nessus Netbios Scanning

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), Snort Community Rules (GPLv2), and MITRE ATT&CK (Apache 2.0).