According to the docs the JIRA User's permission is the permission that allows users to login.
I do not see this permission.
When I look at my global permissions (secure/admin/GlobalPermissions!default.jspa) I only see the following permissions:
I 'm experimenting with permissions and I created a new user and removed it from the jira-core-users group. Now want to give it just the login permission (without having to add it to the jira-core users group).