blackhole(4) on FreeBSD

The text e4edba6b6434, as FreeBSD 4.3-RELEASE, FreeBSD 4.2-RELEASE, FreeBSD 4.1.1-RELEASE, FreeBSD 4.1-RELEASE, FreeBSD 4.0-RELEASE shipped it.

a sysctl(8) MIB for manipulating behaviour in respect of refused TCP or UDP connection attempts.