psql: FATAL: Ident authentication failed for user “username” Error and Solution

Q. I’ve installed Postgresql under Red Hat Enterprise Linux 5.x server. I’ve created username / password and database. But when I try to connect it via PHP or psql using following syntax:
psql -d myDb -U username -W
It gives me an error that read as follows:
psql: FATAL: Ident authentication failed for user “username”
How do I fix this error?

A. To fix this error open PostgreSQL client authentication configuration file /var/lib/pgsql/data/pg_hba.conf :
# vi /var/lib/pgsql/data/pg_hba.conf
This file controls:
  1. Which hosts are allowed to connect
  2. How clients are authenticated
  3. Which PostgreSQL user names they can use
  4. Which databases they can access
By default Postgresql uses IDENT-based authentication. All you have to do is allow username and password based authentication for your network or webserver. IDENT will never allow you to login via -U and -W options. Append following to allow login via localhost only:
local all all trust
host all trust
Save and close the file. Restart Postgresql server:
# service postgresql restart
Now, you should able to login using following command:
$ psql -d myDb -U username -W

article source: