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From: hakanson@ogicse.ogi.edu (Marion Hakanson)
Newsgroups: comp.archives
Subject: [comp.protocols.tcp-ip.domains] Re: How to create /etc/hosts from zone
Keywords: hosts
Message-ID: <1990Nov17.060543.24593@ox.com>
Date: 17 Nov 90 06:05:43 GMT
References: <19523@oolong.la.locus.com> <1667@devildog.att.com> <1990Nov15.185211.876@hemel.bull.co.uk> <1990Nov16.150818.5844@ssd.kodak.com> <14092@ogicse.ogi.edu>
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Archive-name: dnsparse/16-Nov-90
Original-posting-by: hakanson@ogicse.ogi.edu (Marion Hakanson)
Original-subject: Re: How to create /etc/hosts from zone
Archive-site: cse.ogi.edu [129.95.10.2]
Archive-directory: /pub
Reposted-by: emv@ox.com (Edward Vielmetti)

In article <1990Nov16.150818.5844@ssd.kodak.com> sloey@ssd.kodak.com (Jim Sloey (253-7956)) writes:
>. . .
>I tried this [converting /etc/hosts to dns]
> for a while about 3 years ago, but found there was no way to
>keep MX, WKS, and HINFO fields updated without forcing structured comments
>into the host file. 
>Instead I wrote a shell program (makehosts) to create hosts from domain data 
>using nslookup and zone transfers. It is called from an editor (vins) which 
>locks the file and updates the serial field like vipw, then creates a new host 
>table using HINFO for the comments.
>Unfortunately, I left out the CNAMES, so my program won't help you much.

I agree with taking the approach that the DNS files should be the
master database, and that one should produce /etc/hosts files from
them (if necessary).  I have not studied the recently-posted perl
conversion script, but I did spend a lot of effort some time ago to
produce one of my own.

Actually, it is a hybrid, using a C program to pre-process the master
files into a canonical form easily digested by Perl.  There's a Perl
subroutine called "dns_getrr()" which returns the next resource-record
from the master file, and I have a few other scripts which use this
subroutine.  There's a simple one to automatically generate PTR
records from A records, and there's a very involved one which produces
/etc/hosts files.  The latter is pretty fancy, including CNAME's, and
best of all (in my opinion), it produces a hosts file which mimics the
action of the BIND resolver in tacking on default domains to short
aliases (in almost all cases).  In other words, your /etc/hosts file
will behave exactly like a DNS resolver, in all three directions
(name-to-number, number-to-name, and alias-to-FQDN).

It's not perfect, and it's not for everybody, but it works pretty
well here, and it doesn't exercise any DNS servers to do its job.
I call it the dnsparse kit, version 2.0.  You can retrieve it via
anonymous FTP to host cse.ogi.edu, file pub/dnsparse-2.0.tar.Z.

-- 
Marion Hakanson         Domain: hakanson@cse.ogi.edu
                        UUCP  : {hp-pcd,tektronix}!ogicse!hakanson