telnet on local LAN question (progress?)

[Tim]

On Sun, 2011-08-21 at 18:41 -0700, Paul Allen Newell wrote:
> Subject: Returned mail: see transcript for details

Here's the hint (above), whatever mail server you end up playing with.
Look at the transcript of what you get back, and do some searching
against the error/status codes, rather than just some vague, your mail
failed.  You can look into the reasons why it may have failed.  I'd go
looking for some primers on "SMTP error codes" or "SMTP status codes,"
to try and find some documentation that covers them all in one spot for
you to research.

Also, check *very carefully* that your error messages are coming from
where you think they are.  Look at the headers of the returned mails,
and check your server logs.  e.g. Have you actually accessed another
machine on your LAN, or outside of your LAN?

I've done that before.  When I first tried doing what you're trying.  My
mail server machine got the message, and tried to send it through my
ISP's mail server.  Which, naturally, was not going to accept mail for a
domain name that didn't exist on the WWW.
> 
> The original message was received at Sun, 21 Aug 2011 18:17:32 -0700
> from chowder [127.0.0.1]

Ugh, a test mail has come from 127.0.0.1.  You've got machine names
resolving to 127.0.0.1.  Name resolution is up the spout, and it *does*
strike problems with various servers, despite the number of people who
*apparently* get away with putting their machine hostname into the local
loopback addresses in their hosts file.

Have a look at a virgin hosts file, and it'll be like this:

cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1  localhost.localdomain   localhost
::1        localhost6.localdomain6 localhost6

No matter what anybody says, and despite the setup of Fedora doing it,
it's a bad bad BAD idea to bodge *anything* else into those two local
lines.  Sure, you can get away with it under *some* circumstances.  But
you can run into a hell of a lot of pain under other circumstances.

Actual hostnames belong elsewhere, and associated with other IPs.

>     ----- The following addresses had permanent fatal errors -----
> <paul at chalupa.localdomain>
>      (reason: 530 5.7.0 Authentication required)

i.e. Google:  "reason: 530 5.7.0 Authentication required"

Hints:  Are you set up for authenticated mail?  Do you want to be?  Most
people aren't on a home LAN.  And I wouldn't suggest trying until you've
got basic mail working.  If you're not trying to, then turn off mail
server options that check for it.

You'd previously mentioned using different ports, and playing around
with your configuration to suit.  Have you put your servers back to
running on the usual SMTP port 25?

>     ----- Transcript of session follows -----
> ... while talking to chalupa.localdomain.:
>  >>> MAIL From:<paul at localhost.localdomain> SIZE=815
> <<< 530 5.7.0 Authentication required
> 554 5.0.0 Service unavailable

i.e. Google:  "554 5.0.0 Service unavailable"

And this looks, very like, a compounded error.  The first message failed
for one reason, and then another error was encountered.

And notice the "From ..... at localhost.localdomain".  If the receiving
mail is doing any sort of useful verification tests on "from" addresses,
then only mail sent within the same machine would pass the test.  A
message from an external source with that address would be naughty.
Though most home mail servers doing some very basic verification (and
mostly useless) tests, would probably allow it.

This harks back to one of my earlier messages about name resolution.  If
you don't have your basic networking working properly, things get
screwy.  Various clients and servers resolve IPs to find names, and if a
non-127.x.y.z IP *resolves* to localhost.localdomain, regardless of you
believing hostnames and domain names have been set correctly, you are in
for headaches.

I really don't recall this level of pain when I first tried my own SMTP
serving.  I'd recommend setting up your hosts files to best practice,
learn DNS serving (later on, save that headache for later, but you'd
need to know it for doing mail properly).  Replace your customised mail
server configuration files with virgin ones, read some documentation,
and carefully customise them again.  First try using a central mail
server, get that working before you try SMTP on each machine (i.e. send
all mail to usernames at that-server, from different machines on your LAN).
If you're in a safe LAN, do your experimenting with no firewalls between
machines, or make sure that port 25 is allowed between all your LAN
machines.

-- 
[tim at localhost ~]$ uname -r
2.6.27.25-78.2.56.fc9.i686

Don't send private replies to my address, the mailbox is ignored.  I
read messages from the public lists.