How to disable port 137 to 139 netbios in debian 03.08.17

find out what app is using it.
most properly its samba,
uninstall it if you don't need it:

apt-get remove samba

if you get like:
Dear Sir or Madam,

NetBIOS defines a software interface and a naming convention.
NetBIOS over TCP/IP provides the NetBIOS programming interface
over the TCP/IP protocol.

Over the past months, systems responding to NetBIOS nameservice
requests from anywhere on the Internet have been increasingly
abused for DDoS reflection attacks against third parties.
The NetBIOS nameservice uses port 137/udp.

Please find below a list of affected systems hosted on your network.
The timestamp (timezone UTC) indicates when the openly accessible
NetBIOS nameservice was identified.

We would like to ask you to check this issue and take appropriate
steps to secure the NetBIOS nameservices services on the affected
systems or notify your customers accordingly.

If you have recently solved the issue but received this notification
again, please note the timestamp included below. You should not
receive any further notifications with timestamps after the issue
has been solved.

Additional information on this notification, advice on how to fix
reported issues and answers to frequently asked questions:
<BSI - CERT-Bund Reports>

This message is digitally signed using PGP. Information on the
signature key is available at the aforementioned URL.

Please note:
This is an automatically generated message. Replies to the
sender address <reports@reports.cert-bund.de> will NOT be read
but silently be discarded. In case of questions, please contact
<certbund@bsi.bund.de> and keep the ticket number [CB-Report#...]
of this message in the subject line.

https://www.myridia.com/bsi.bund.de

Anonymous

How to disable port 137 to 139 netbios in debian 03.08.17

Information Epoch 1762616807