A network monitoring “sensor” is built on initial startup by checking the integrity of the bootstrap system and, if it passes, downloading information from which it builds the full system including an encrypted and an unencrypted portion. Later, the sensor sends hashes of files, configurations, and other local information to a data center, which compares the hashes to hashes of known-good versions. If they match, the data center returns information (e.g., a key) that the sensor can use to access the encrypted storage. If they don't, the data center returns information to help remediate the problem, a command to restore some or all of the sensor's programming and data, or a command to wipe the encrypted storage. The encrypted storage stores algorithms and other data for processing information captured from a network, plus the captured/processed data itself.