Information
For each NFS export, ensure that the secure option is selected.
Rationale:
Secure NFS uses DES encryption or Kerberos to authenticate hosts involved in RPC transactions. RPC is a protocol used by NFS to communicate requests between hosts. Secure NFS mitigates attempts by an attacker to spoof RPC requests by encrypting the time stamp in the RPC requests. A receiver successfully decrypts the time stamp and confirms that it is correct. This serves as a confirmation that the RPC request came from a trusted host.
Solution
Use chnfsexp to change/validate this value for all NFS exported filesystems:
chnfsexp -d <fs> -S <sec>
The available security method options are:
sys - UNIX authentication
dh - DES authentication
none - Use the anonymous ID if it has a value other than -1
krb5 - Kerberos. Authentication only
krb5i - Kerberos. Authentication and integrity
krb5p - Authentication, integrity, and privacy '
Once all exported filesystems have been successfully validated or changed, re-export the filesystems and directories to activate the new options:
exportfs -a
Default Value:
N/A
Additional Information:
Reversion: Copy back the original /etc/exports:
cp -p /etc/exports.pre_cis /etc/exports