This how-to was forked from ageis' gist on building a grsec-patched kernel for Debian 8 and DigitalOcean.
grsecurity is "an extensive security enhancement to the Linux kernel that defends against a wide range of security threats through intelligent access control, memory corruption-based exploit prevention, and a host of other system hardening".
Note: The stable patches are not publicly available anymore, so we'll be applying the free 4.7.2 (test) patch. The URLs and filenames in this document may become outdated, so fetch the latest from grsecurity.net and kernel.org.
Install dependencies: