https://www.thedailybeast.com/exclusive-lone-dnc-hacker-guccifer-20-slipped-up-and-revealed-he-was-a-russian-intelligence-officer

«But on one occasion, The Daily Beast has learned, Guccifer failed to activate the VPN client before logging on. As a result, he left a real, Moscow-based Internet Protocol address in the server logs of an American social media company, according to a source familiar with the government’s Guccifer investigation. Twitter and WordPress were Guccifer 2.0’s favored outlets. Neither company would comment for this story, and Guccifer did not respond to a direct message on Twitter.

Working off the IP address, U.S. investigators identified Guccifer 2.0 as a particular GRU officer working out of the agency’s headquarters on Grizodubovoy Street in Moscow. (The Daily Beast’s sources did not disclose which particular officer worked as Guccifer.)»