Portal rocket turrets

I am making a map where the player has to get the rocket from the rocket sentry, to hit a brush entity, to set off a trigger, but how would I make it so that only rockets from the sentry set it off.

filter_activator_name or filter_activator_class. Make a func_button made with nodraw, make it to only be set off by damage, and use the filters to make sure it only recognizes things from the sentry. I don’t know if this would work because I don’t have portal, but its an idea.