blackhole(4) on FreeBSD

The text 8efa8c881525, as FreeBSD 5.5-RELEASE, FreeBSD 5.4-RELEASE, FreeBSD 5.3-RELEASE, FreeBSD 5.2.1-RELEASE, FreeBSD 5.2-RELEASE shipped it.

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