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Re: QPopper "warning"

Kevin Traas wrote:
> I've been getting the following message in /var/log/messages ever since I
> installed qpopper on my system:
> Dec  2 13:09:35 inetgw in.qpopper[742]: (v2.2) Unable to get canonical
> name of client, err = 0
> Everything works fine, but I always get that message - filling up the log
> files....
> Anyway, I finally found the solution to this problem....
> All clients on my LAN are retrieving mail from mail.<dn> which is
> resolvable via DNS and is the same system as inetgw (identified in log
> entry above).  (named is also on this same box, fwiw.)
> Anyway, I solved this problem by adding an entry for "mail mail.<dn>" in
> /etc/hosts.....  Now, no more log entries....
> Can anyone tell me why qpopper couldn't resolve the mail.<dn> name via DNS
> and requires an entry in /etc/hosts?  Design limitation?

Interesting. I wouldn't think what you did would fix it. The api for 
name/IP lookup makes it transparent to the program whether /etc/hosts
or DNS is used. This is all done in the c library (gethostbyname(),
If adding the entry to /etc/hosts fixed the problem though, then all 
evidence indicates that there's a missing reverse-mapping in DNS. 
Note that the error says 'Unable to get canonical name' which indicates
it's trying to map from IP to a FQDN (fully qualified domain name). 
In DNS you actually have to make two separate entries to do this one
to map from foo.bar.com to and another to do the "reverse"
If /etc/hosts is used though, only a single entry suffices for forward
reverse mapping. 

The only weird thing is that the error indicates that the *client's* 
canonical name couldn't be found. I could see the being the case only
if the users were running a pop client from "main.DN".

Jens B. Jorgensen

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