We recently got a complaint from our Information Security Office indicating that our Master server was attempting to connect to all of the virtual machines in our virtual environment over port 137. The firewall between the master server and the virtual machines was alerting them that there were excessive firewall denies. I created a new case with Veritas, and asked them to provide documentation on what purpose this communication served. They couldn't explain what the communication was for. Since we couldn't determine what the communication was for, we had to turn off NetBIOS over TCP/IP on that interface, which stopped the problem.
However, in order to upgrade the software, we have to have NetBIOS over TCP/IP enabled.
Does anyone know why this port would be used, and why it would be attempting to connect to all the virtual machines? According to the Firewall Port Requirements, port 137 is only used for SQL client hosts using a "remote registry service." But there are no SQL clients in that vCenter.