How to reach asterisk on a private network from outside?

Hi, first of all sorry if i ask a stupid question but i’m new to the (actually wonderful!) world of VoIP…

I’ve an Asterisk server running on linux on a private network (10.x.x.x) that works flawless.

Now I’d like to be able to access this Asterisk server from internet using another linux pc with public ip that (right now) acts as an http proxy server for 10.x.x.x network.

What should i configure/install on “public” pc to access private asterisk?
I can’t understand, first of all, if i can do it and if i need a sip proxy (which one?) or if i should create an ip tunnel or whatever…

Please, be aware that asterisk server on 10.x.x.x network can access (via tcp, udp, rtp) the proxy server but it’s not nat-ted…

Best regards and thanks in advance

Your best option there is probably to use a tunnel / VPN. If you can get a tunnel happening between the two systems, you’re three quarters of the way there.