rsbackup The server never initiates a connection. Client initiates connection via ssh, public key, no password The server accepts three commands from the client, identified by the following regex's: ^prepare \w+ [a-zA-Z_.-]+$ ^cleanup \w+ [a-zA-Z_.-]+$ ^rsync --server .*\. $LOCALBACKUP_PATH[A-Zaz-0-9./_-]+$ Client machine passes in Client Name and Machine Name Client/Machine name is matched against source IP Start Time In other words, machine may only make a connection if Source IP address is correct Start Time is within a specific range public key matches the one recorded on server It attempts to execute one of the three commands; prepare, cleanup and rsync The rsync target path is a subdirectory of a specific directory on the server Server configuration file contains regex to match for cleanup, prepare and rsync Amount of "slop" in time matching (set to +/- 30 minutes on my machine) for each client list of machines which can back up for each machine list of modules to execute for cleanup and prepare; those are not passed in time of day backup may be initiated IP address backup may come from all of these may be set to '', in which case backup can come from any IP, at any time, with no action take for prepare or cleanup