PID randomization was never available in the mainstream Linux kernel. Apart from individual initiatives, for several years it was mainly available through grsecurity kernel patch, however it was removed in the late 2006:
grsecurity 2.1.10 was released today for Linux 2.4.34 and 2.6.19.2. Changes in this release include:
- Removal of randomized PIDs feature, since it provides no useful additional security and wastes memory with the 2.6 kernel's pid bitmap
This completes my randomized PID implementation comparison between Linux, OpenBSD and FreeBSD :).
