Both ping(8) and ping6(8) obfuscate the transmitted monotonic clock values
by offsetting them with a random value.
ChaCha streams are used to vary every payload. This helps the user to hide the system time from the attacker and prevents OS detection.
More Details:
- OpenBSD 5.8 Changelog
- obfuscate the monotonic clock values we put on the wire by offsetting · openbsd/src@08eef1f · GitHub
- ping(8), ping6(8) - OpenBSD manpages