How to disable CIFS Null Sessions on VNX FILE or Celerra?

## To disable CIFS Null Sessions (no data mover reboot is required)

[nasadmin@nyvnxcs0 ~]$ server_param server_2 -f cifs -modify nullSessionNotOnFS -value 0

server_2 : done

## To check current parameter value

[nasadmin@nyvnxcs0 ~]$ server_param server_2 -f cifs -info nullSession

server_2 :

name                    = nullSession

facility_name           = cifs

default_value           = 1

current_value           = 0

configured_value        = 0

user_action             = none

change_effective        = immediate

range                   = (0,1)

description             = Allows Null Session connection to share

The parameter cifs.nullSession allows client to use Null Session (no username, no password) to connect to a share.

By default, user will be able to login, but not read/write on the File System. The mapped UID for such user is -2 value.

param cifs nullSession=0 prevents clients from connecting to a share when using Null Session.

param cifs nullSession=1 allows clients to connect to a share without username and password.

Please also refer to cifs.nullSessionNotOnFS parameter.