Virtual network interfaces for OS X
http://tuntaposx.sourceforge.net/ Formula was removed
Last versions were

Recent formula history

Anastasia Sulyagina tuntap: migrate to cask.
Viktor Szakats tuntap: use secure url in download hint, fix audit problem
Nikolaus Wittenstein Add descriptions to all remaining homebrew packages
Mike McQuaid unsigned_kext_req: use new cask/download DSL.
Mike McQuaid tuntap: set kext cask and binary.

Formula code at GitHub