When using an external authentication system such as Ident or GSSAPI, the name of the operating system user that initiated the connection might not be the same as the database

Authentication failures and related problems generally manifest themselves through error messages like the following:

Client authentication is controlled by a configuration file, which traditionally is named pg_hba.conf and is stored in the database cluster's

The following subsections describe the authentication methods in more detail. 20.3.1. Trust Authentication