Usually, when I want to connect to my LAN from the Wild Wild World, I use a VPN connexion. But there are times when it is not possible ; especially now that my work LAN has the same IP range as my home LAN… An alternate way to access my unpublished home services from outside is to use SSH tunnels.
What you need is an SSH server on the LAN that you want connect to. The SSH server has to be able to connect to the LAN server you aim to connect to. Then, all you have to do is a bit of “Port Forwarding”.