User 4574
From The Stargate Omnipedia
N.I.D. user identification for Colonel Frank Simmons. Simmons used this access code to unlock files on all SG-1 personnel. He was quite upset when he learned Samantha Carter discovered his infiltration, and he threatened that he could destroy her career because she hacked the system during his investigation of her and her team.
KEY EPISODE
The Fifth Man - Carter discovers User 4574 has been accessing her team's files.