how to setup SSH user with limit permission?

Question

There are some sites provide SSH accounts only for ssh tunnel. I want to know how to make sure these accounts can only have permission to do tunnel, and how to do limit settings.

And I also notice that github ssh format is ssh://[email protected]:{gituser}/{project}.git , so, I guess github.com use a git account for everyone, but this git account has very limit permission, when user access $gituser/ folder, it do authenticate in another way.

I really want to know how.

Answer 1

The first part of your question is exact duplicate of this: How to restrict SSH users to a predefined set of commands after login?

Github blog has a long post in their blog on their architecture.

But in case you want to set up a git repository for multiple users, then there's project called Gitolite.