If you are exporting file systems using NFS service, be sure to configure the /etc/exports file with the most restrictive access possible. This means not using wildcards, not allowing root write access, and mounting read-only wherever possible.
Example 5.1. Export file systems using NFS
Edit the exports file vi /etc/exports and add:
/dir/to/export host1.mydomain.com(ro,root_squash)
/dir/to/export host2.mydomain.com(ro,root_squash)
Where:
[root@deep]# /usr/sbin/exportfs -a