In order to host git repositories, you don't really need any "git server". You just need to be able to generate a git repository (from wherever you have git) and copy over the repository to your host.
http://git-scm.com/book/ch4-2.html[
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Git itself doesn't handle permissions either, they're left to be handled by the file system. If a user has access to the repository files, he has access to the repository.