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Date:      Mon, 27 Nov 2000 22:36:46 -0800 (PST)
From:      dima@unixfreak.org (Dima Dorfman)
To:        ekholm@ekholm.org (Mike Ekholm)
Cc:        questions@freebsd.org
Subject:   Re: DNS problems
Message-ID:  <20001128063646.BB2BB3E08@bazooka.unixfreak.org>
In-Reply-To: <20001127224805.A35818@ekholm.org> from "Mike Ekholm" at Nov 27, 2000 10:48:05 PM

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Mike Ekholm wrote:
> 
> hello,
> I am running in to some odd problems with name resolution. Here is what I am
> seeing:
> 
> ekholm@zeus:/home/ekholm> w
> 10:42PM  up 106 days, 23:24, 14 users, load averages: 0.75, 1.08, 0.94
> USER             TTY      FROM              LOGIN@  IDLE WHAT
> ekholm           p0       bigone           Sun09PM    33 -ksh (ksh)
> ekholm           p1       bigone           20Nov00     - -ksh (ksh)
>
<snip who(1) output>
> 
> ekholm@zeus:/home/ekholm> last|more
> ekholm           ttyp0    192.168.0.17     Sun Nov 26 21:46   still logged in
> ekholm           ttyp1    192.168.0.17     Mon Nov 20 19:00   still logged in
> ekholm           ttypc    isis.XXXX.XXX    Mon Nov 27 22:26   still logged in
> ekholm           ttyp8    j1xsfw01.XXXX.XXX Mon Nov 27 08:05   still logged in
> 
> 
> The question is, why does w show the name I am from, but who and
> last do not.

w(1) does a DNS lookup on all the hostnames it gets from the utmp
file.  last(1) and who(1) don't.

> This happens with almsot any host in my 192.168.0/24, but does NOT happen
> with IPs in other blocks (as shown in the last).

When who(1) and last(1) show hostnames, it is because whatever program
wrote to the utmp/wtmp files recorded the DNS entry in ut_host rather
than a numeric address.  As stated before, w(1) always does a DNS
lookup, so you always get a hostname from it if it can find it.

As to why some of your connections get recorded with numeric address
and others with DNS names, perhaps you're using different methods to
log in?  For example, IIRC, ftp records the DNS name in ut_host, while
telnetd records the numeric address.

> 
> Another problem is, this machine is running a IRC server, for some reeason
> connecting clients are not resolving, shows user@ip instead od
> user@dom.com

Can you resolve the name manually using host(1)?  Can you telnet or
ping the hostname?  If you answered yes to the former but no the
latter, you may want to check out /etc/resolv.conf or resolver(5).

Hope this helps

-- 
Dima Dorfman <dima@unixfreak.org>
Finger dima@unixfreak.org for PGP public key.


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