How do I login to a Postgres database without a password?

Question

Right now my Postgres' pg_hba.conf file has the following lines:

# "local" is for Unix domain socket connections only
local all all md5
# IPv4 local connections:
host all all 127.0.0.1/32 md5
# IPv6 local connections:
host all all ::1/128 md5
#Should allow connection without password
host all all 0.0.0.0/0 trust
host all all ::0/0 trust

(I know that this is insecure. I'm just testing, and once it is successful, I'll keep it only specific users & databases)

My understanding was that trust should allow a user to connect without a password.

But when I do psql -U postgres -d postgres -h 127.0.0.1 -w, I get the error message: psql: fe_sendauth: no password supplied

What do I need to do to allow users to connect without a password?

• user1822: Did you reload the configuration after changing the file?
• Devdatta Tengshe: Yes, I did that. I'm sure that it is loaded, because I had made a mistake in the file earlier, and postgres refused to load till I corrected it.
• user1822: Is there any line before those that you have shown us?
• Devdatta Tengshe: @a_horse_with_no_name; I've updated the question

Answer 1

When pg_hba.conf is checked for an authentication request, the first match determines the rule.

Quote from the manual

The first record with a matching connection type, client address, requested database, and user name is used to perform authentication. There is no "fall-through" or "backup": if one record is chosen and the authentication fails, subsequent records are not considered

^{(Emphasis mine)}

In your case the lines:

host all all 127.0.0.1/32 md5
# IPv6 local connections:
host all all ::1/128 md5

are matched before the trust lines you have added, therefor Postgres requires a password. If you want to disable password authentication completely you have to disable the md5 authentication, e.g. by commenting those lines.