# 21.14. BSD Authentication
This authentication method operates similarly to
password except that it uses BSD Authentication to verify the password. BSD Authentication is used only to validate user name/password pairs. Therefore the user's role must already exist in the database before BSD Authentication can be used for authentication. The BSD Authentication framework is currently only available on OpenBSD.
BSD Authentication in PostgreSQL uses the
auth-postgresql login type and authenticates with the
postgresql login class if that's defined in
login.conf. By default that login class does not exist, and PostgreSQL will use the default login class.
To use BSD Authentication, the PostgreSQL user account (that is, the operating system user running the server) must first be added to the
auth group. The
auth group exists by default on OpenBSD systems.