I see Fortuna as default now, before freebsd 10.4 yarrow algorithm enabled by default
kern.random.fortuna.minpoolsize: 64
kern.random.harvest.mask_symbolic: [UMA],[FS_ATIME],SWI,INTERRUPT,NET_NG,NET_ETHER,NET_TUN,MOUSE,KEYBOARD,ATTACH,CACHED
kern.random.harvest.mask_bin: 00111111111
kern.random.harvest.mask: