Port 139 — NetBIOS-SSN

TCP · Port 139/TCP is used for the NetBIOS-SSN (Session Service) protocol, which enables communication between devices on a local network. This service is responsible for establishing and terminating connections between NetBIOS applications. It plays a crucial role in file sharing and printing services.

Port Number: 139
Service Name: NetBIOS-SSN
Protocol: TCP
Common Software: Samba, Windows

Security Notes

Review IANA registry for port 139 usage. Apply principle of least privilege - only open ports that are required.

FAQ

What is port 139 used for?

Port 139 is used for NetBIOS-SSN. Port 139/TCP is used for the NetBIOS-SSN (Session Service) protocol, which enables communication between devices on a local network. This service is responsible for establishing and terminating connections between NetBIOS applications. It plays a crucial role in file sharing and printing services. Common software: Samba, Windows.

Is port 139 dangerous to leave open?

Review IANA registry for port 139 usage. Apply principle of least privilege - only open ports that are required.

How do I check if port 139 is open?

Use nmap: nmap -p 139 <target> or check locally: ss -tlnp | rg 139