pfsync(4) on OpenBSD
The text c73fc2bc45bf, as OpenBSD 5.6, OpenBSD 5.5, OpenBSD 5.4, OpenBSD 5.3, OpenBSD 5.2, OpenBSD 5.1, OpenBSD 5.0, OpenBSD 4.9, OpenBSD 4.8 shipped it.
packet filter state table sychronisation interface
The text c73fc2bc45bf, as OpenBSD 5.6, OpenBSD 5.5, OpenBSD 5.4, OpenBSD 5.3, OpenBSD 5.2, OpenBSD 5.1, OpenBSD 5.0, OpenBSD 4.9, OpenBSD 4.8 shipped it.
packet filter state table sychronisation interface