1. A method for use with a server and a group of associated hosts, comprising: storing in the server meta-information states relating to files seen on the hosts, the meta-information including a signature of the content of the files; storing for each signature, an initial time; at defined periods related to the initial time, performing at least one security analysis of the file, or analysis of the signature of the file contents; and altering the file state and providing information related to the altered state to the hosts