Sometimes I just want to get a copy of a file from GIT here’s how I do it:

git cat-file blob HEAD~25:src/experiment/BasicStacking.java

Can be combined with a redirect to a file

git cat-file blob HEAD~25:src/experiment/BasicStacking.java > BS.java

Since I so seldom setup ssh I always forget the details, here is a good guide:
Setup SSH keys

An addition to this is that you may have to do ssh-add on the client to get it working.