What is port UDP 137 used for?

Port 137 is utilized by NetBIOS Name service. Enabling NetBIOS services provide access to shared resources like files and printers not only to your network computers but also to anyone across the internet.

What type of traffic is normally seen over UDP port 137?

NBNS traffic
The well known UDP port for NBNS traffic is 137. TCP: NBNS can also use TCP as its transport protocol for some operations, although this might never be done in practice.

What port number is 137?

Service Name and Transport Protocol Port Number Registry

Service Name Port Number Description
netbios-ns 137 NETBIOS Name Service
netbios-ns 137 NETBIOS Name Service
trim 1137 TRIM Workgroup Service
trim 1137 TRIM Workgroup Service

What is UDP port 445 used for?

Side note: UDP port 445 uses the Datagram Protocol, a communications protocol for the Internet network layer, transport layer, and session layer. This protocol when used over PORT 445 makes possible the transmission of a datagram message from one computer to an application running in another computer.

Is port 445 UDP or TCP?

TCP port 445 is used for direct TCP/IP MS Networking access without the need for a NetBIOS layer. In Windows NT it ran on top of NetBT (NetBIOS over TCP/IP, ports 137, 139 and 138/udp).

What’s the UDP traffic on ports 137 and 138?

I’m seeing a lot of broadcast UDP traffic on ports 137 and 138 being dropped that is coming from other workstations on the same network segment. I’ve already configured DHCP to set the NETBIOS setting to disable NETBIOS over TCP/IP, and I’ve verified that the setting has been disabled on the workstation NIC.

What does port 137 mean on the Internet?

NetBIOS name resolution is meant for LANs and WANs. The Internet is just one big WAN. NetBIOS is MS proprietary. Also if you tracert to a site, you’ll see TCP port 137 requests on every hop to that site, including the site.

Why does my computer send UDP packets to websites?

What I would like to understand is why browsing websites is causing my system to send UDP packets on port 137 to the websites I am browsing. NetBIOS over TCP/IP may be causing it, if you have it installed and enabled. Tribus: On a mote of dust suspended in a sunbeam.

Why do I See denied outbound SMB traffic?

You should see the denied outbound SMB traffic on our corporate firewall: 100 MB of logs every day. The reason you see it is because Windows is trying to resolve the remote host via NetBIOS name as well as with DNS. Do a tracert to *some web server*.