On Fri, 24 May 2024 11:40:30 -0400 Greg Wooledge <g...@wooledge.org> wrote:
> On Fri, May 24, 2024 at 05:22:14PM +0200, Marco Moock wrote: > > Am 24.05.2024 um 17:17:45 Uhr schrieb to...@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. > Long ago, lo used to be just 127.0.0.1, which is what most people would try to ping to check localhost, and what appeared in /etc/hosts. There is some subtle reason, which I used to know but have now long forgotten, why Debian started using 127.0.1.1 in /etc/hosts instead. As far as I'm aware, any 127. address will resolve to localhost. -- Joe
