I would like to use my Raspberry Pi 2 mainly as a media center but also as a private git server for small projects like LaTeX documents.
My goal is to be able to set this server as a remote repo to push to and pull from over the web with various interfaces (Linux shell, Windows Git-tortoise). On the other hand, I would like to prevent unauthenticated access to my home network and my Pi.
Since there are multiple ways of achieving this and I am not an expert regarding IT security, I would like to know if someone can recommend or has experience with a certain setup:
My first idea was to enable port-forwarding inside my router for SSH access to the Pi. This seems to work, however, I would have to change the default username and password, or anyone would be able to access the device. I would also have to create a new (somehow restricted) user account if I ever wanted to share the repo.
What other possibilities are there to achieve this functionality?