Postgres not allowing localhost but works with 127.0.0.1

Question

Postgres not accepting connection if I say -h localhost but it works if I say -h 127.0.0.1

[root@5d9ca0effd7f opensips]# psql -U postgre         


        

Answer 1

The Problem

Postgres will potentially use IPv6 when specifying -h localhost which given the above pg_hba.conf specifies ident, a password prompt will be returned.

However when -h 127.0.0.1 is specified, it forces Postgres to use IPv4, which is set to trust in above config and allows access without password.

---

The Answer

Thus the answer is to modify the IPv6 host line in pg_hba.conf to use trust:

# IPv6 local connections:
host    all         all         ::1/128               trust

Remembering to restart the Postgres service after making config changes.