First excuse if this text doesn't go in this thread of the forum or this solution already exists in the forum, but I eat there is not a searcher of terms in the forum, I will take a risk and I will publish it.
Recently I met with a problem when making work the net in virtual box in way bridge, we need to have loaded two modules to use the net in way bridge.
The solution is simple, to create two soft links of the modules vboxnetflt.ko and vboxnetadp.ko that are in the route /programs/Virtualbox.x.X./modules to /boot/modules ( use ln -s ).
After this to publish the file /boot/loader.conf and to add the you line vboxnetflt_load="YES" and vboxnetadp_load="YES."
After this, to begin virtualbox and we already have way enabled bridge and working.
A greeting from Spain
P.D: thanks to Gon to be discovered this fantastic system that has made me return to the long nights and the headaches of when I began with linux :evil: