There should be consistency in /etc/group and /etc/gshadow.
Run the grpck command to check that these two files reconcile.
grpck
result:
no matching group file entry in /etc/gshadow add group 'sambasecureshare' in /etc/gshadow? y 'john' is a member of the 'sshusers' group in /etc/group but not in /etc/gshadow 'root' is a member of the 'tomcat' group in /etc/gshadow but not in /etc/group
As can be seen there are a number of inconsistencies.
Lets fix these.
Action: