RE: [cobalt-users] Cube2 slow pop3 logins

[erichelm@xxxxxxxxxxxx (Eric Helm)]

Thanks for the information. Here is some more info.
When the name.domain_name.tld format is used in the client machines as the
mail server address, the problem occurs.
When the internal ip of the cobalt machine is used, the problem goes away.
The name.domain_name.tld points to an ip which is forwarded by a cable modem
provider to a private ip on the cable providers network.  So there is some
address translation happening with the cable provider.  In addition, the ip
addresses that reappear in the maillog file are those of the cable provider,
one of them being a router address.  DNS is being hosted by the cable
provider.  Is this a problem with the cable provider's dns, or something
else on there end?  Like I mentioned before this problem has no always
occured and editing the host file is not a solution that I want to use if
there are other problems with the cable provider.

-----Original Message-----
From: cobalt-users-admin@xxxxxxxxxxxxxxx
[mailto:cobalt-users-admin@xxxxxxxxxxxxxxx]On Behalf Of Colin J. Raven
Sent: Wednesday, June 06, 2001 6:26 PM
To: cobalt-users@xxxxxxxxxxxxxxx
Subject: RE: [cobalt-users] Cube2 slow pop3 logins


<snip>
> It appears that the mail program is trying to do reverse dns
> or something.
> Any ideas to fix this?
> When the internal network ip of the cube is used as the pop
> and smtp server
> address, everything works great.
> Here is a sample of the maillog file where I suspect is the
> problem: There
> are a few hundred lines similar to this.
>
> Jun  6 07:50:35 mail in.qpopper[12172]: (v?) POP login by
> user "xxxxxxx" at
> (xxx.xxx.xxx.xxx) xxx.xxx.xxx.xxx
> Jun  6 07:50:38 mail in.qpopper[12173]: (v?) Unable to get
> canonical name of
> client xxx.xxx.xxx.xxx: Host name lookup failure (2)
<snip>
You are essentially correct in your assessment of the problem
Some thoughts and questions:
From: http://www.eudora.com/qpopper/faq.html#canonical
What does the error message Unable to get canonical name of client mean?
This error message in your log means that a client connected in and
Qpopper got an error when it tried to do a reverse lookup on the IP
address.  If the client is local, this may indicate a problem with its
DNS entry (specifically the PTR record for that IP address), or it may
be a temporary DNS problem.
Qpopper allows you to turn off this check if you like.  Qpopper also
includes the IP address of the client in the log message, to make it
easier to check its DNS entries.

Now previously, someone posted a reasonable answer for this, and that is
to populate your hosts file with all LAN client IP's and machine names.
Have you done that???

If you did, and (say for example) a road warrior comes in with a laptop
and an IP/name that isn't in the hosts file you could still get the same
problem happening with the same cause. Recheck all client entries
again....there's a 95% chance that is where your problem is.

Another possibility is that you have a machine on your LAN with an IP
but no name.

You mention that when you use the IP of the machine as the SMTP/POP3
settings, everything "works great" so let me ask you....is this event
happening when you use something *other than* the IP of the server in
the mail client(s)????? what are you using instead of the IP? the
machine name.domain_name.tld notation??? Is **that** when this
happens???? That's a whole different issue if so.

More info definitely needed, but look at your hosts file first for the
IP/machine_name in question for user "xxx" referred to in your post
above.
Oh, did I mention that you should probably check your hosts file? <grin>

Good luck and keep the list informed of steps taken and results. Your
pain today could be someone's salvation tomorrow in the archives.

Regards & HTH,
-Colin
--
Colin J. Raven



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