Cannot Close 137 udp port - ubuntu

if you face some complains about port 137 udp netbios-service is open on your server and firewall cannot close these ports then check if you have samba or cifs installed on your system, then remove this service completely unless you need it for an important application.
Uninstall cifs-utils from Ubuntu 16.04
To remove cifs-utils package :

 
sudo apt-get remove cifs-utils

Uninstall cifs-utils and it's dependent packages

 
sudo apt-get remove --auto-remove cifs-utils

delete configuration and data files of cifs-utils :

 
sudo apt-get purge cifs-utils

delete configuration and data files of cifs-utils and it's dependencies :

 
sudo apt-get purge --auto-remove cifs-utils