I've purchased a rack-mounted RB2011 and wAP ac, more commonly known as RBwAPG-5HacT2HnD (lol these model names), within the last 3 years that did not have firewall enabled and contained no firewall rules by default. If I had to guess it was around ROS 6.32 or 6.33 release for 2011 and recently for the wAP.