The Camp McCarran supply shack is a shack inside Camp McCarran in the Mojave Wasteland in 2281. To get to the shack from the central Camp McCarran field where all the tents are pitched, first enter the terminal building, then climb the escalators to the second floor, and proceed down the hallway marked "Concourse" to the sets of doors. Go through the doors into the Concourse, then bear left down a ramp to the nondescript door that is the entrance to the supply shack. Daniel Contreras does his shady business there.
The ground floor mainly consist of some large crates against the wall, along with some shelves and lockers. The middle section is mostly empty. The second floor, accessible by stairs, has a computer terminal and a bed.
There is an exit door behind Daniel Contreras, this makes for a quicker fast-travel exit from the area than retracing your steps through the concourse.