Re: strange behavior of pg_hba.conf file

Please can you share any command for due diligence whether ip is resolved
to ipv6 ?.

On Wed, Nov 22, 2023 at 11:25 PM Andreas Kretschmer <andreas(at)a-kretschmer(dot)de>
wrote:

>
>
> 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
>
>
>
>