From the 4.2 release page: http://www.dragonflybsd.org/release42
> The SCTP protocol (an alternative to TCP and UDP) has been removed. Its code was originally written at the beginning of the 2000s and having never been updated since then, it was starting to become a problem for the general evolution of the network stack. Not having had any known user in 15 years, its removal was an obvious choice.