A front-end server uses the Database Wire Protocol (DWP) to communicate with a back-end server. Because DWP uses HTTP as the transport mechanism, Calendar Server provides authentication for DWP connections between front-end and back-end servers using configuration parameters.
When the front-end server first connects to the back-end server, it sends the user ID and password specified in the ics.conf file. The back-end server checks the parameters in its ics.conf file, and if both parameters match, the authentication is successful. The back-end server then sends a session ID back to the front-end server. The front-end server uses the session ID in subsequent DWP commands to the back-end server.
Subsequent connections from the same front-end server do not need to be authenticated again, unless the back-end server is restarted or the session expires because of no activity between the two servers.
If you have multiple front-end and back-end servers, you can use the same user ID and password for each one.
If a back-end server does not specify a user ID and password, no authentication is performed.