pcap_get_selectable_fd(3) on FreeBSD
The text 4d6143436a49, as FreeBSD 10.4-RELEASE, FreeBSD 10.3-RELEASE, FreeBSD 10.2-RELEASE, FreeBSD 10.1-RELEASE, FreeBSD 10.0-RELEASE, FreeBSD 9.3-RELEASE, FreeBSD 9.2-RELEASE, FreeBSD 9.1-RELEASE shipped it.
get a file descriptor on which a select() can be done for a live capture