Master-slave configuration: interface-related question

[PA3FUN]

Hi Guru's. I've got Smokeping up-and-running in a stand-alone setup. I would however like to deploy a master-slave setup.
Q: How do master and slave(s) communicate with one another? Yes, I've read that the webserver is used for that purpose. But does that imply that both master and slave(s) should have their webservers up-and-running or just the master? In the first case this would require the slaves to be accessible from the outside world, requiring port-forwarding whenever they reside behind a firewall. That would be a serious drawback in my situation :( . In my ideal world only the master would need to run a webserver, and the slaves would only require the smokeping process to be active.
Any help appreciated!

[moetiker]

Only the Controller Server needs the Webserver Worker not.
Worker are pulling the config from the Controller and push the data to the Controller.

[Strykar]

Also see https://github.com/oetiker/SmokePing/wiki/FAQ#master-slave-setups