Deciphering blocked connection attempts

In the past couple days, there has been an upsurge in blocked connection attempts--it is almost continuous.  Here for instance, is the information indicated in the inspector window.

 

Direction: Incoming

Action: Denied

Type: User-defined setting

Protocol: UDP

IMCP info:

Remote Address: 192.168.1.2

Port: 137

Host: 192.168.1.2

Local Address: 192.168.1.3

Port: 49189

Host: 192.168.1.3

 

Remote address always ranges from 192.168.1.2 through 192.168.1.4.  It seems to be scanning systematically going from port 49189 to 49190 to 49191 and so on.

 

I would appreciate any assistance deciphering these connection attempts.

 

Thanks in advance.