[Xymon] SMTP test needs much more capability

[Shawn Heisey]

I have been chasing down the following.  The first is the smtp status 
reported on the xymon status page (which is green), debian package 
version 4.3.0-0.beta2. The second is a corresponding message from 
mail.log on the Postfix (2.7.1 debian package) server.

220 nexus2.example.com ESMTP Postfix (Debian/GNU)
503 5.5.1 Error: send HELO/EHLO first
221 2.0.0 Bye

May 20 10:08:15 nexus2 postfix/smtpd[8689]: improper command pipelining 
after MAIL from mcp.example.com[10.2.1.39]

After a lengthy exchange with Wietse Venema on the postfix-users mailing 
list, I got to the bottom of it, and there's no problem with postfix.  
The 503 error is because Xymon does not send a HELO.  I've determined 
that if I send the following, I can avoid the 503 error:

helo xymon
mail from: xymon at example.com
quit

If I modify the smtp test to send these strings, the "improper 
pipelining" message is still logged.  This is because Xymon is breaking 
SMTP rules by not waiting for the response to each command before 
sending the next one.  There are no longer any errors logged during the 
actual SMTP session, because I have added the xymon server to a list 
that allows it to get away with improper pipelining, and to another one 
that lets it send invalid HELO strings and FROM addresses.

This would be a problem if I had to monitor a remote postfix server 
whose configuration I could not control, though.  The only reason that 
the test passes is that the string it looks for (220) is returned in the 
initial banner, before any SMTP commands are sent.  It is not actually a 
real test.  Any number of postfix configuration errors would keep the 
server from working, yet still return the banner on initial connect.

Does anyone know how to make Xymon smart enough to wait for a defined 
response on each command before sending the next, and to put custom 
commands into a config file, rather than built in at compile time via 
protocols.cfg?  Ideally it would be able to understand that any 4nn or 
5nn code is a problem as well.  I will take a look at the code, but my 
programming skills are rusty.

Thanks,
Shawn