OpenBSD Implementation Random Number System Kernel: TCP ISN TCP Timestamp Ephemeral Source Port IPID, IPv6 Fragment ID Userland: BIND Time Protocols Obviously, we're ignoring pseudo-randomness we inject for explicitly cryptographic reasons in IPSec, ssh, carp, etc. In accordance with OpenBSD's "No useless buttons" policy, we turn these on by default. Actually, there is usually no way to turn them off - it's totally transparent to the user.