Uses the pg_ident.conf file to match the connecting user with the PostgreSQL database user name. These users are on the local network (your network structure may be different). It uses the connecting user name to evaluate if that user has permission to connect or not. If you want to allow a user to connect as a different user name from the connecting user name, add a record into the pg_ident.conf file. For more information on this file, refer to the next section.
host booktown 18.104.22.168 255.255.255.255 ident sameuser
For more examples, take a look at the pg_hba.conf file under the $PGDATA directory (/usr/local/pgsql/data/). It contains a comment section with several different examples.
To add a single line comment into this file, use the hash mark (#) to start the beginning of a comment.