Using out-of-the-box Alfresco this is not possible without additional customisation / implementation. While Alfresco provides FTP server capablities, it does not have FTP client capabilities that would be required for such a use case. Without going into Java development for this, you could achieve a simple active publish process by having an external script (i.e. a shell script triggered by a Linux CRON) that accesses Alfresco via FTP and copies / publishes relevant structures to another FTP service. If your Alfresco content structure is already set up in the way that you want to have in the target FTP server, you may even be able to use something like rsync to only synchronize any files / folders that have actually been changed.
