gradm is used to manage the ACL system of GrSecurity. Please note that you will need a specially patched kernel for GrSecurity to work (see the kernel-patch-2.4-grsecurity Debian package). Also, gradm was deprecated together with the kernel patch, users are advised to upgrade to gradm2 and kernel-patch-grsecurity2 Debian package. You can find more information about GrSecurity at http://www.grsecurity.net/