I'm currently comparing random PID implementation on OpenBSD, FreeBSD and Linux from security perspective.
As long as OpenBSD and FreeBSD are concerned, my work is done. However, while the answer here states that random PID can be enabled on Linux just thanks to a
sysctl setting, I was not able to determine which setting it is.
Researches on Internet only lead to patches and discussions rejected in the mainstream Linux kernel, and it does not appear in the grsecurity features either (and obviously on my Linux boxes PIDs are incremental everywhere, with no
sysctl parameter name seeming related, and a few searches in the kernel source did not show anything relevant).
Is PID randomization really available on Linux?