Linux Firewalls, Third Edition

Greater Security with GrSecurity

GrSecurity, formally known as Greater Security, is a kernel patch and userspace program for enhancing the security of a Linux system. GrSecurity, also referred to as Grsec, closes some avenues for attack and makes others much more difficult. Grsec implements a sophisticated Access Control List (ACL) for objects in Linux. The ACL can be used to provide much more granular control over files and other resources. For example, using a Grsec ACL, you can control what files will be shown as the result of a find command or which processes are included in process accounting logs.

Grsec also enables a system called PaX to restrict the capability of processes to alter memory space. This aspect alone renders many types of ...