Developed by Dr. Gaius Baltar, the Command Navigation Program (CNP) was a program utilized by the Colonial military forces of the Twelve Colonies. Installed in the central computers of Vipers and Raptors and in the navigation computers of almost all battlestars, the CNP was a contrivance of more than two years in the making.
Unbeknownst to Baltar, a lover and co-writer of the CNP turned out to be a version of the Cylon agent viewers know as Number Six. She programmed backdoors into the program so that the Cylon attack force could break through the Colonial firewalls. Ships with the CNP that received a command from attacking Cylon ships would, in the case of Vipers and Raptors, be shut down "as if a switch were flipped." Battlestars suffered system failures of various kinds before their computers shut down.
The CNP was distributed as with all Colonial software updates via the Colonial Defense Mainframe, where Six had unrestricted access on Baltar's authorization.
The CNP was received by battlestar Galactica, but the program was never loaded into primary memory of the ship, although her last squadron of Viper Mark VIIs (led by CAG Jackson Spencer) received the upgrade. As a result, the squadron was massacred by two Raiderss on their way back to Caprica (Miniseries).
Lieutenant Felix Gaeta has the program code purged from the mainframe on Baltar's suggestion, and the program is also retrograded on the flight systems of Galactica's surviving Mark VII Vipers and Raptors.