Re: domain names, was: hostname
On Wed 21 Mar 2018 at 20:02:55 (+0000), Brian wrote:
> On Tue 20 Mar 2018 at 17:07:47 -0500, David Wright wrote:
>
> > On Fri 23 Feb 2018 at 16:18:29 (+0000), Brian wrote:
> > >
> > > With
> > >
> > > 127.0.1.1 gmail
> > >
> > > in /etc/hosts the conversation would go like this:
> > >
> > > brian@desktop:~$ telnet bendel.debian.org 25
> > > Trying 82.195.75.100...
> > > Connected to bendel.debian.org.
> > > Escape character is '^]'.
> > > 220 bendel.debian.org ESMTP Postfix
> > > helo gmail
> > > 250 bendel.debian.org
> > > mail from:<someone@debian.org>
> > > 250 2.1.0 Ok
> > > rcpt to:<debian-user@lists.debian.org>
> > > 504 5.5.2 <gmail>: Helo command rejected: need fully-qualified hostname
> > >
> > > gmail.com is ok with bendel.
> > >
> > > OTOH:
> > >
> > > brian@desktop:~$ telnet cloud11.unlimitedwebhosting.co.uk 25
> > > Trying 149.255.60.164...
> > > Connected to cloud11.unlimitedwebhosting.co.uk.
> > > Escape character is '^]'.
> > > 220 cloud11.unlimitedwebhosting.co.uk ESMTP Postfix
> > > helo gmail
> > > 250 cloud11.unlimitedwebhosting.co.uk
> > > mail from:<someone@debian.org>
> > > 250 2.1.0 Ok
> > > rcpt to:<deblis@lionunicorn.co.uk>
> > > 250 2.1.5 Ok
> > > data
> > > 354 End data with <CR><LF>.<CR><LF>
> > >
> > > cloud11.unlimitedwebhosting.co.uk appears not to be bothered by the
> > > helo; bendel is.
> >
> > In common with a lot of home users, I can't connect to external
> > machines on port 25. I assume that's because my ISP doesn't want
> > to have their IP range affected by people spamming from it.
> >
> > Are the dialogues above meant to show that you're at liberty to
> > insert emails into those hosts because you have/could have typed
> > helo gmail.com at the prompt? Is that what an open relay is?
>
> The two dialogues show that different mail servers treat what is
> in the HELO/EHLO in two quite distinct ways. bendel cares what the
> HELO/EHLO says; cloud11.unlimitedwebhosting couldn't care less. I
> think both are RFC compliant.
>
> The behaviour of cloud11.unlimitedwebhosting does not turn it into
> an open relay.
Should I assume that that's because you chose rcpt addresses that the
host ought to recognise as deliverable? But like many ".home users",
I submit emails for various addresses to smtp.lionunicorn.co.uk so
this approach wouldn't work, would it?
But to be honest, I've never engaged in a conversation like the second;
the closest is the following (though I don't use this port):
telnet smtp.lionunicorn.co.uk 25
Trying 149.255.58.10...
Connected to smtp.lionunicorn.co.uk.
Escape character is '^]'.
220 cloud11.unlimitedwebhosting.co.uk ESMTP
ehlo west
250-cloud11.unlimitedwebhosting.co.uk
250-AUTH=LOGIN CRAM-MD5 PLAIN
250-AUTH LOGIN CRAM-MD5 PLAIN
250-STARTTLS
250-PIPELINING
250 8BITMIME
^]
telnet> quit
Connection closed.
As you can see, there's now an AUTH response.
[From your other post]
> You don't talk to people except through an intermediary? I prefer to
> know what happens to the mails I send.
No, I send and receive all my emails through an always-up machine,
rather than running one here. It also avoids having to open up
ports for when I'm travelling. A lot of people do this, and it's
likely that many of them have LANs at home whose names are best
drawn from .home, .corp and .mail.
Cheers,
David.
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