You can create a Private Server for you and your Friends, with Hamachi, and a Root (and DynDNS but i dont know how with this

) Root costs money but it it 24/7 hours online, Hamachi only when you start it, and your Friends need to be in you hamachi network. Then you need Serverfiles (Daroo, Invoice). But you can see a how to on YouTuBe :
Sorry for bad English