The Command Navigation Program (abbreviated CNP) is an operating system designed for use among Colonial spacefaring vessels, both civilian and military. It was primarily developed by Gaius Baltar, a leading scientist and computer expert.
Installed in the central computers of Vipers and Raptors and in the navigation computers of almost all battlestars as well as many civilian vessels, the CNP is in widespread use at the time of the Cylon attacks.
The Cylon infiltrator Number Six seduced Baltar to gain access to the CNP code under the guise of improving it and to allow her company an advantage during a bidding process in future; during her modifications, she installed a covert backdoor in the code so that the Cylon attack forces could render any ships that use the operating system to shut itself down by remote command.
Due to this, Battlestars and fighters approaching Cylon forces are quickly shut down and destroyed without being able to fire back; the malfunctions are described as being "as if a switch were flipped." Many reports of "system failures" come in from throughout the Fleet; at least one battlestar is reported as completely losing power just before contact with Cylon forces. The only ships that survived the massacre were ones that didn't have networks or the CNP loaded onto their systems, either due to system antiquity (in the case of the Battlestar Galactica and her vintage squadron of Viper Mark IIs) or which had their networks shut down for some reason (in the case of the Battlestar Pegasus, which was in drydock in preparation for a refit and which had not recieved the CNP yet).
Surviving ships all have their CNP code purged from their systems, with their computer systems being rolled back to older, less vulnerable software as well as their networks being disconnected.