Re: strange behavior of pg_hba.conf file

Am 22.11.23 um 18:44 schrieb Atul Kumar:
> I am giving this command
> psql -d postgres -U postgres -p 5432 -h localhost
> Then only I get that error.

so localhost resolved to an IPv6 - address ...

>
> but when I  pass ip or hostname of the local server then I don't get
> such error message
> 1. psql -d postgres -U postgres -p 5432 -h <ip of local server>
> 2. psql -d postgres -U postgres -p 5432 -h <hostname of local server>

resolves to an IPv4 - address. you can see the difference?

localhost != iv4-address != hostname with ipv4 address

Andreas

>
>
> I don;t get that error while using the above two commands.
>
>
> Regards.
>
>
> On Wed, Nov 22, 2023 at 10:45 PM Adrian Klaver
> <adrian(dot)klaver(at)aklaver(dot)com> wrote:
>
> On 11/22/23 09:03, Atul Kumar wrote:
> > The entries that I changed were to replace the md5 with
> scram-sha-256
> > and remove unnecessary remote IPs.
>
> FYI from:
>
> https://www.postgresql.org/docs/current/auth-password.html
>
> md5
>
>      The method md5 uses a custom less secure challenge-response
> mechanism. It prevents password sniffing and avoids storing
> passwords on
> the server in plain text but provides no protection if an attacker
> manages to steal the password hash from the server. Also, the MD5
> hash
> algorithm is nowadays no longer considered secure against determined
> attacks.
>
>      The md5 method cannot be used with the db_user_namespace feature.
>
>      To ease transition from the md5 method to the newer SCRAM
> method,
> if md5 is specified as a method in pg_hba.conf but the user's
> password
> on the server is encrypted for SCRAM (see below), then SCRAM-based
> authentication will automatically be chosen instead.
>
> >
> > But it has nothing to do with connecting the server locally with
> "psql
> > -d postgres -U postgres -h localhost"
>
> The error:
>
> no pg_hba.conf entry for host "::1", user "postgres", database
> "postgres
>
>
> says it does and the error is correct as you do not have an IPv6
> entry
> for localhost in pg_hba.conf. At least in the snippet you showed us.
>
>
> >
> > But when I try to connect it locally I get this error. So it is
> related
>
> When you say connect locally do you mean to localhost or to
> local(socket)?
>
> > to local connections only and when I pass the hostname or ip of the
> > server it works fine without any issue.
> >
> >
> > Regards.
> >
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>

--
Andreas Kretschmer - currently still (garden leave)
Technical Account Manager (TAM)
www.enterprisedb.com