topic telnet to mail server no interactive in automatic shell in Operating System - HP-UX

telnet to mail server no interactive in automatic shell

Jairo Campana — Fri, 01 Apr 2005 15:56:15 GMT

I've read many examples about using a shell script to test a mail server
> (sendmail, postfix, etc) such as:
> #!/bin/bash
> telnet 1.2.3.4 25 << _EOF_
> HELO abc.com
> <- smtp conversation here (mail from, rcpt to, data, etc)
> _EOF_
>
> When I execute it, I get:
> 220 xyz.com ESMTP Sendmail 8.11.6/8.11.6; Fri, 11 Oct 2002
> 19:59:20 -0400
> Connection closed by foreign host.
>
> I've tried many ways to do it but it doesn't work. I've read somewhere that
> "telnet is not interactive so it will not work". I know Perl is much better
> and gives more control, but I want to do it first en bash script just for
> fun :) Any suggestion?

Re: telnet to mail server no interactive in automatic shell

Rick Garland — Fri, 01 Apr 2005 16:06:27 GMT

If the service (telnet) and the port (25) is enabled to accept the connections, you should be able to interact with SMTP.

It may be set to deny logins outside of the SNMP services.

Re: telnet to mail server no interactive in automatic shell

Jeff Schussele — Fri, 01 Apr 2005 16:18:27 GMT

Hi Jairo,

Check the /etc/mail/sendmail.cf on that system.
Look for PrivacyOptions and IF it's set to "goaway" then almost all SMTP status queries are disallowed.
If it's needmailhelo then the system will insist on an HELO or EHLO before it will allow any mail commands.

Also sendmail is *very* picky about name resolution. Make sure both the server & client are resolvable both forward (by name) & reverse (by IP). Sendmail will shoot you down if you're not.

Rgds,
Jeff

Re: telnet to mail server no interactive in automatic shell

harry d brown jr — Sat, 02 Apr 2005 07:00:38 GMT

can you do it MANUALLY??

If so, then the problem is your script.

Stuff like this should be done in perl.

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=209253
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=696550

live free or die
harry d brown jr

Re: telnet to mail server no interactive in automatic shell

Daryl Much — Mon, 04 Apr 2005 09:14:40 GMT

FWIW, here's how I do it via perl. I don't use telnet but setup a real smpt connection instead.

HTH,

Chuck Davis
#####

#!/usr/bin/perl -w

use Net::SMTP;

$usage =<
this script checks if an SMTP server is available on a server. run like this:

$0

script exits with 0 if SMTP is running, exits with 1 if SMTP not running.

EOF
;

if (@ARGV != 1)
{ print $usage;
exit;
}

$server = $ARGV[0];

if (Net::SMTP->new( $server, Timeout=>5))
{ print "SMTP on $server is UP\n";
exit 0
}
else
{ print "SMTP on $server is DOWN\n";
exit 1
}