10.7.2. Host Access in NFSv4

The release of NFSv4 brought a revolution to authentication and security to NFS exports. NFSv4 mandates the implementation of the RPCSEC_GSS kernel module, the Kerberos version 5 GSS-API mechanism, SPKM-3, and LIPKEY. With NFSv4, the mandatory security mechanisms are oriented towards authenticating individual users, and not client machines as used in NFSv2 and NFSv3. As such, for security reasons, Red Hat recommends the use of NFSv4 over other versions whenever possible.

Note

It is assumed that a Kerberos ticket-granting server (KDC) is installed and configured correctly, prior to configuring an NFSv4 server. Kerberos is a network authentication system which allows clients and servers to authenticate to each other through use of symmetric encryption and a trusted third party, the KDC.

NFSv4 includes ACL support based on the Microsoft Windows NT model, not the POSIX model, because of the former's features and wide deployment. NFSv2 and NFSv3 do not have support for native ACL attributes.

Another important security feature of NFSv4 is the removal of the use of the MOUNT protocol for mounting file systems. This protocol presented possible security holes because of the way that it processed file handles.

For more information on the RPCSEC_GSS framework, including how rpc.svcgssd and rpc.gssd inter-operate, refer to http://www.citi.umich.edu/projects/nfsv4/gssd/.