Re: Address 127.0.1.1

From	Paul M Foster <paulf@quillandmouse.com>
Newsgroups	linux.debian.user
Subject	Re: Address 127.0.1.1
Date	2024-05-24 18:20 +0200
Message-ID	<IHFO9-fxbD-1@gated-at.bofh.it> (permalink)
References	<IHBUd-fuUh-3@gated-at.bofh.it> <IHEp3-fwe2-9@gated-at.bofh.it> <IHES5-fwCW-3@gated-at.bofh.it> <IHF1L-fwGk-3@gated-at.bofh.it> <IHFl7-fwN0-3@gated-at.bofh.it>
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On Fri, May 24, 2024 at 11:40:30AM -0400, Greg Wooledge wrote:

> On Fri, May 24, 2024 at 05:22:14PM +0200, Marco Moock wrote:
> > Am 24.05.2024 um 17:17:45 Uhr schrieb tomas@tuxteam.de:
> > 
> > > On Fri, May 24, 2024 at 04:49:18PM +0200, Marco Moock wrote:
> > > 
> > > [...]
> > > 
> > > > If you operate mail servers, you must have a FQDN. .lan can't be
> > > > used for the global DNS stuff, so set a proper FQDN that belongs to
> > > > you.  
> > > 
> > > I think this is wrong in that sweeping generality.
> > 
> > In the case it should communicate with other MTAs in the internet, this
> > will be true because many of them require a resolvable (also reverse)
> > FQDN in HELO/EHLO that matches the IPv4/IPv6 addresses of the server.
> 
> Most MTAs do not look in /etc/hosts when reading their configuration.
> Whatever name they identify with (in the HELO or EHLO command) comes
> from some MTA-specific configuration file.
> 
> Thus, the contents of /etc/hosts are for *other* things, not related to
> MTA configuration.  Just being able to resolve your own hostname to any
> address that "works" is the goal.  127.0.1.1 works well for this, which
> is why Debian uses it as the default.  If you've got a static LAN address,
> you can use that instead.

I should note that this is apparently not true for OpenSMTPD. In fact,
there is or was a bug in it, such that if you had two instances of
127.0.0.1 in your hosts file, OpenSMTPD would fail with a message that it
couldn't listen on address 127.0.0.1 because it was already in use (or
somesuch).

Paul

-- 
Paul M. Foster
Personal Blog: http://noferblatz.com
Company Site: http://quillandmouse.com
Software Projects: https://gitlab.com/paulmfoster

Thread

Address 127.0.1.1 Paul M Foster <paulf@quillandmouse.com> - 2024-05-24 14:10 +0200
  Re: Address 127.0.1.1 Greg Wooledge <greg@wooledge.org> - 2024-05-24 14:20 +0200
  Re: Address 127.0.1.1 Dan Ritter <dsr@randomstring.org> - 2024-05-24 14:40 +0200
  Re: Address 127.0.1.1 Marco Moock <mm@dorfdsl.de> - 2024-05-24 16:50 +0200
    Re: Address 127.0.1.1 <tomas@tuxteam.de> - 2024-05-24 17:20 +0200
      Re: Address 127.0.1.1 <tomas@tuxteam.de> - 2024-05-24 17:30 +0200
      Re: Address 127.0.1.1 Marco Moock <mm@dorfdsl.de> - 2024-05-24 17:30 +0200
        Re: Address 127.0.1.1 Greg Wooledge <greg@wooledge.org> - 2024-05-24 17:50 +0200
          Re: Address 127.0.1.1 Paul M Foster <paulf@quillandmouse.com> - 2024-05-24 18:20 +0200
          Re: Address 127.0.1.1 Joe <joe@jretrading.com> - 2024-05-24 18:50 +0200
            Re: Address 127.0.1.1 Paul M Foster <paulf@quillandmouse.com> - 2024-05-24 19:20 +0200
              Re: Address 127.0.1.1 Andy Smith <andy@strugglers.net> - 2024-05-24 23:40 +0200
            Re: Address 127.0.1.1 Greg Wooledge <greg@wooledge.org> - 2024-05-24 19:40 +0200
      Re: Address 127.0.1.1 Joe <joe@jretrading.com> - 2024-05-24 18:50 +0200
        Re: Address 127.0.1.1 <tomas@tuxteam.de> - 2024-05-24 19:20 +0200
  Re: Address 127.0.1.1 Greg Wooledge <greg@wooledge.org> - 2024-05-24 19:50 +0200
    Re: Address 127.0.1.1 Jeffrey Walton <noloader@gmail.com> - 2024-05-24 20:00 +0200
      Re: Address 127.0.1.1 Greg Wooledge <greg@wooledge.org> - 2024-05-24 20:30 +0200
        Re: Address 127.0.1.1 debian-user@howorth.org.uk - 2024-05-24 23:30 +0200
  Re: Address 127.0.1.1 Jeffrey Walton <noloader@gmail.com> - 2024-05-24 19:50 +0200
    Re: Address 127.0.1.1 David Wright <deblis@lionunicorn.co.uk> - 2024-05-24 19:50 +0200

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