MAMP Server Security Basic Question

[Reg88]

Is MAMP server for LOCAL testing only secure by default in the sense that unless you setup DynDNS or something like that then the MAMP server is NOT accessible to the outside world???

And if you were to try to allow outside access TO your MAMP server, am I correct that you'd need to specifically open a port in your OS X firewall?

E.g. Can you accidentally allow MAMP server to be accessed from the outside world?

Thanks.