No reason not to contact them, but yes, they actively recruit too.
The floor was full of huge expensive noisy booths from big corporations, universities and other government agencies. In contrast the NSA booth was the most basic booth on the floor. There was a simple printed sign in standard Helvetica font, same as used on all the cheap booths, with the agency's name (no logo), one guy in a suit sitting behind a bare table, and one chair in front of the table for visitors. Nothing else. The sheer minimalism of it made it impressive. I wanted to take a picture but, well, you know...