Port
Port 138 — NetBIOS datagram
Port 138 (UDP) is used by NetBIOS datagram. NetBIOS Datagram Service.
Port 138 at a glance
| Property | Value |
|---|---|
| Port number | 138 |
| Transport | UDP |
| Service | NetBIOS datagram |
| Category | Well-known port |
What it is used for
NetBIOS Datagram Service.
Security considerations
Block at the perimeter.
See our full TCP/UDP port reference and learn how firewalls filter ports in the CyberOps course.
Frequently asked questions
What is port 138 used for?
Port 138 (UDP) is used by NetBIOS datagram. NetBIOS Datagram Service.
Is port 138 TCP or UDP?
Port 138 uses UDP.
Is it safe to open port 138?
Block at the perimeter.
Related
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