To use Kerberos authentication for NFS, GSS security must be enabled. To do so, select in the initial YaST dialog. Note, that you must have a working Kerberos server to install this feature. YaST does not set up the server but only uses the provided functionality. If you want to use Kerberos authentication, in addition to the YaST configuration, complete at least the following steps before running the NFS configuration:
Make sure that both the server and the client are in the same Kerberos domain. This means that they access the same KDC (Key Distribution Center) server and share their krb5.keytab file (the default location on any machine is /etc/krb5.keytab).
Start the gssd service on the client with rcgssd start.
Start the svcgssd service on the server with rcsvcgssd start.
For further information about configuring kerberized NFS, refer to the links in Section 28.5, For More Information.