[CLUE-Tech] how to troubleshoot smtp server

[David L. Willson]

-----Original Message-----
From: clue-tech-admin at clue.denver.co.us
[mailto:clue-tech-admin at clue.denver.co.us]On Behalf Of Jim Ockers
Sent: Tuesday, 05 February, 2002 11:06
To: clue-tech at clue.denver.co.us
Subject: Re: [CLUE-Tech] how to troubleshoot smtp server


Jeffrey:

This could be a firewall issue as Ed suggests, but given my experience with
Red Hat 7.2 you could be up against an "off-by-default" situation that Red
Hat set up.

The default sendmail configuration for Red Hat 7.2 is to listen only on the
IP address 127.0.0.1 and port 25.  This will cause other systems on the
network
to be unable to connect to sendmail on your box, even though sendmail is
running fine and you can connect to it on localhost.

If you run the following command "netstat -an | grep LIST | grep ^tcp" you
will see all of the TCP listeners on your system.  You should see something
like this:

[3] danja.int.ca.pason.com:/home/ockers > netstat -an | grep LIST | grep
^tcp
tcp        0      0 0.0.0.0:6000            0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:139             0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:515             0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:110             0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:23              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:21              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:989             0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:1024            0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN

Notice how on my system I am listening on the address 0.0.0.0 and port 25.
This means that my system is accepting connections on all network interfaces
for port 25 (sendmail).

On your system, I am betting that the listener is "127.0.0.1:25" and that
you
do not have sendmail bound to any other interfaces.  You can verify this by
running the netstat command.

The way to fix this is in the /etc/sendmail.cf or in the
/etc/mail/sendmail.mc.
Here is the sendmail.mc information:

dnl This changes sendmail to only listen on the loopback device 127.0.0.1
dnl and not on any other network devices. Comment this out if you want
dnl to accept email over the network.
dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')

The daemon_options above are commented out.  Yours are probably not
commented
out.  If you comment it out, then run "make" in the /etc/mail directory,
then
restart sendmail, your problem should go away.

Hope this helps.

--JimO

> On Tue, 2002-02-05 at 10:23, Jeffrey Greer wrote:
> > Hi,
> >
> > I'm new to this list.  I plan to attend my first CLUE meeting next week
and I
> > would like to get involved.
> >
> > I've been using linux for 4 years, but I have not done much real system
> > administration.  I am having a problem setting up email on a dedicated
linux
> > server I just purchased.  The remote machine is buddha.whitebuddha.com.
When
> > I send email from a remote machine via smtp it just gets lost.  Sendmail
is
> > running at buddha and I can send email locally with pine, but nothing
comes
> > in remotely.  I can't find anything in /var/log/maillog.  I'm running
redhat
> > 7.2.  I've configured the nameserver at www.dnsmadeeasy.com.
Dnsmadeeasy.com
> > automatically edits the soa file through a web form.  I've set up the MX
> > record to point to whitebuddha.com.
> >
> > I don't really have any idea how to troubleshoot this or what docs to
look
> > at.  Could someone here give me some suggestions?
> >

> Looks like you might have the firewall configured so that it isn't
> allowing incoming SMTP traffic.  You can use "lokkit" to check and/or
> edit the firewall rules.

--
Jim Ockers (ockers at ockers.net)
Contact info: please see http://www.ockers.net/

Fight Spam! Join CAUCE (Coalition Against Unsolicited Commercial Email)
at http://www.cauce.org/ .

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