Subject: Reverse DNS...

From: "Edward Baichtal" <[email-masked]>
Date: Tue, 8 Dec 1998 17:24:51 -0800

How do I turn off reverse DNS lookups in wu-ftpd?  Or is this a function of
Linux that I need to do?  If so where is it (if you happen to know)?

--------------------------
Edward Baichtal
[email-masked]
http://www.airlink.com

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From: Gregory A Lundberg <[email-masked]>
Date: Wed, 9 Dec 1998 08:49:16 -0500 (EST)

On Tue, 8 Dec 1998, Edward Baichtal wrote:

> How do I turn off reverse DNS lookups in wu-ftpd?  Or is this a
> function of Linux that I need to do?  If so where is it (if you happen
> to know)?

If you're set up using tcpd (tcpwrappers) in your inetd.conf you can
remove tcpd and eliminate one source of reverse-DNS lookups.

The daemon itself does another set of reverse-DNS lookups.  Running the
standard beta-18 release, you cannot disable this.  The VR-series includes
a compile-time option to remove all DNS activity (forward and reverse).
Removing reverse-DNS from the daemon disables all abilities to use machine
names in ftpaccess and ftphosts and any security checks based upon name in
the daemon.  It was put in at the request of very busy FTP sites and
should not be used unless you are *completely* aware of the risks
involved.

If you're just looking to eliminate a few dozen lines per hour of DNS
messages from your bind, my recommendation would be to live with the log
messages.

If it's a particular site causing problems, notify the DNS admin for that
site and have the problem corrected.

Personally, I see a few thousand FTP-related DNS errors a day and ignore
them.  Mostly their lame deligations with a few responses from unexpected
sources and the occassional NODATA.  As long as the pattern stays as
expected, I don't worry .. there's a lot of very messed up corporate and
academic networks out there.  I allow myself one-a-day to investigate
fully and notify the DNS admin of the results; I find most admins are
unaware of the problems and greatly appeciate the report and suggestions. 

-- 

Gregory A Lundberg		Senior Partner, VRnet Company
1441 Elmdale Drive              [email-masked]
Kettering, OH 45409-1615 USA    1-800-809-2195