I'm using the Git Fusion OVA running in VirtualBox to submodule a Perforce repository into a git repository. I've set up users to be members of the git-fusion-push group, and that group is a subgroup of a group with write access to the depot containing the linked repository.
I've had two users have had their pushes rejected by the pre-receive hook, due to lack of authentication. I managed to reenable one use through various permission changes, while I was trying to work out what was wrong (I made them a superuser temporarily to check that the mechanics was working, which it was - they could then push).
This may or may not be connected to the users trying to push a non-fast-forward commit.
I'm a Perforce beginner.