I have a Little Snitch (a third-party firewall application) on my Macbook running OS 10.11.1.
I noticed that because of my settings to deny most incoming connections from the LAN, the launchd process automatically denied an attempted incoming connection from an internal IP address (192.168.0.2) on UDP port 137 (NBNS).
I'm aware that NBNS is related to NetBIOS but I'm still not too sure of what it actually does. Was a machine on my LAN attempting to connect to mine in order to find out what the basics of my machine (like model or make or something)? I've never noticed a connection like this before so I'm curious if I should be worried.
In the screenshot: despite the arrow next to the IP address going rightwards, there's a symbol next to the log that indicates it was incoming.