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<TITLE>The Answer Guy 50: Double Reverse DNS Strikes Again</TITLE>
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<H4>By James T. Dennis,
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<H3 align="left"><img src="../../gx/dennis/qbubble.gif"
height="50" width="60" alt="(?) " border="0"
>Double Reverse DNS Strikes Again</H3>
<p><strong>From Nelson Carvalho on Tue, 18 Jan 2000
</strong></p>
<!-- ::
Double Reverse DNS Strikes Again
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:: -->
<P><STRONG>
hello
<br>im contacting regarding linux. i have linux box with apach and fpt and
<tt>sendmail</tt> (pop3,smtp) and a dns server and dhcp server and it work fine and
fast from linux machine to linux machine. now i also have this linux box
connected to a few windows machines, now i try to <tt>ftp</tt> from the windows
machine to the linux box and it takes at least 90 seconds for it to connect
to it, once connected it is fast and good. it also does the same thing if i
try using outlookexpress to check email on the linux box. it takes about 90
seconds for it to connect and send messages, just wondering if you have any
suggestions on what might be happening?
<br>the web browser for www works with no hesitation, only ftp and mail take 90
seconds or more to establish a connection.
<br>also these computers are not connected to the internet, its a private
network.
</STRONG></P>
<P><STRONG>
i appriciate any help u could give me
<br>thanks.
</STRONG></P>
<BLOCKQUOTE><IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
>
It sounds like you don't have DNS nor <TT>/etc/hosts</TT> entries
for your MS Windows clients. If you add the IP addresses
and some names for those clients to one or the other of
these then your problem will probably go away.
</BLOCKQUOTE>
<BLOCKQUOTE>
Search my back issues on the string "double reverse dns"
or "double reverse lookup" for the gory details. (Hint:
it has to do with TCP Wrappers and how it figures how
"who" is connecting so that it can log the connection and
so that it can make policy decisions according to the
content in your <TT>/etc/hosts.allow</TT> and <TT>/etc/hosts.deny</TT> files).
</BLOCKQUOTE>
<BLOCKQUOTE>
The easiest and smartest solution is to make sure that
you have proper reverse entries in your DNS zones and/or
your <TT>/etc/hosts</TT> files for all of your systems.
</BLOCKQUOTE>
</BLOCKQUOTE>
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