How to get easily (from a script) all CNAME of a A record?

[Philippe.Simonet at swisscom.com]

Hi

If you have control over all zones, you could also pre-store the results of
your search in DNS :)

For all CNAME records, make e.g. a TXT record with the reverse result :
(TXT is maybe not the better record type...which ones (for specialists))

For each :
a-name IN A 1.2.3.4
an-alias IN CNAME a-name

Just add :
a-name IN TXT an-alias

and make more than one TXT records for each cname pointing to the same record ...
a-name IN TXT another-alias

best regards

Philippe


From: bind-users-bounces+philippe.simonet=swisscom.com at lists.isc.org [mailto:bind-users-bounces+philippe.simonet=swisscom.com at lists.isc.org] On Behalf Of Stacey Jonathan Marshall
Sent: mardi 9 novembre 2010 16:53
To: bind-users at lists.isc.org
Subject: Re: How to get easily (from a script) all CNAME of a A record?

On 09/11/2010 14:14, Michelle Konzack wrote:

Hello Matus UHLAR - fantomas,



Am 2010-11-09 14:13:47, hacktest Du folgendes herunter:

I am not sure whether dnswalk over whole internet can do that, but on your



I will try it...



server you can either run recursive grep over named data directory, or dump

the named dsatabase and grep it...



This is what I currently do...



----[ '/usr/sbin/get_hosts_in cname' ]----------------------------------

#!/bin/sh



QUERY="$1"



for FILE in $(cd /etc/bind && ls *.signed)

do

  grep --regexp=" IN CNAME .*${QUERY}" /etc/bind/${FILE} 2>/dev/null |cut -d ' ' -f1 |sed 's|.$||'

done

------------------------------------------------------------------------



...and it is to slow do to more then  80.000  Zones  (they  have  to  be

greped all) number of VHosts.



Oh, it is now time to use "xargs", because I saw today, that I  hit  the

limits for "ls".  :-D



Following is working:

    cd /etc/bind && ls



but not:

    cd /etc/bind && ls *

or

    cd /etc/bind && ls *.signed



and the OSes are called Linux and BSD...  WTF?



It seems that a commandline can not have more then 31.000 characters.

(no not options but total lenght)



Thanks, Greetings and nice Day/Evening

    Michelle Konzack


The asterisk causes the shell to expand the names and run ls with them as a single command, so in effect you have "ls file1 file2 file3 ...".   Try the following instead:



cd /etc/bind

for FILE in *.signed

do

  grep --regexp=" IN CNAME .*${QUERY}" ${FILE} 2>/dev/null |cut -d ' ' -f1 |sed 's|.$||'

done
It might still have the same issue, but worth a go.

I assume the command length is also why your not simply running "grep -h <expression> *.signed"?

Stace






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