If you wanted to do this "enterprise port knocking" on OpenBSD, you could use pf to do this. https://www.openbsd.org/faq/pf/authpf.html https://www.openbsd.org

If you wanted to do this "enterprise port knocking" on OpenBSD, you could use pf to do this. https://www.openbsd.org/faq/pf/authpf.html https://www.openbsd.org/faq/pf/authpf.html The FAQ entry is about building an authenticated gateway, but the same technique can be applied to open individual ports.