How a retired technician handed EFF the proof of NSA mass spying
Mark Klein, a retired AT&T technician, provided the Electronic Frontier Foundation with evidence of the NSA's mass internet surveillance in 2006. He revealed that a secret room in an AT&T building in San Francisco was copying all internet traffic passing through the facility. His documentation showed the scale of the surveillance program, which EFF used to challenge the NSA's activities.
- ▪Mark Klein discovered a secret room, labeled 641A, in an AT&T building that copied all internet traffic for the NSA.
- ▪The copied data was routed through a splitter cabinet that duplicated fiber-optic signals without causing detectable delays.
- ▪A telecom expert reviewing the documents described the operation as a 'country tap,' indicating mass surveillance rather than targeted wiretapping.
- ▪After EFF filed the evidence, the Justice Department requested the documents be sent via a secure fax machine in a SCIF due to their sensitivity.
Opening excerpt (first ~120 words) tap to expand
How a retired technician handed EFF the proof of NSA mass spying Ellsworth Toohey 4:03 pm Thu Apr 30, 2026 Jeff Whyte/shutterstock.com On the sixth floor of an AT&T building on Folsom Street in San Francisco, a locked room labeled 641A held the hardware that gave the NSA a copy of every byte of internet traffic passing through. The man who figured this out was a retired AT&T technician named Mark Klein, and in January 2006 he walked into the lobby of the Electronic Frontier Foundation a few blocks away and started talking. Cindy Cohn, then EFF's legal director, recounts the encounter in The MIT Press Reader, in an excerpt from her book Privacy's Defender. Klein told EFF's executive director Shari Steele that he could prove the NSA was tapping the internet backbone at scale.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Boing Boing.
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