It is common to use LDAP as access protocol for such a user-management.
For simple requirements you can
- setup your own custom LDAP server with appropriate schema
- use MS Active Directory preferrably with sssd
You can use one of the usual LDAP-NSS/PAM integration components which are pretty mature today (in no particular order):
For more complex requirements, e.g. authorization based on host groups, you may want to use full-featured solutions more dedicated to Linux/Unix:
- FreeIPA using 389-DS as back-end, preferably with sssd
- Æ-DIR using OpenLDAP as back-end, with any NSS/PAM implementation for LDAP, or in large setups preferably with aehostd
Full disclosure: I'm the project maintainer behind Æ-DIR and therefore I'm biased of course.