a Strange Deletion

Glenn Satchell Glenn.Satchell at uniq.com.au
Wed Mar 22 23:22:40 UTC 2006

>X-Original-To: dhcp-users at webster.isc.org
>To: dhcp-users at isc.org
>Subject: Re: a Strange Deletion 
>Date: Wed, 22 Mar 2006 15:13:08 -0600
>From: Martin McCormick <martin at dc.cis.okstate.edu>
>Glenn Satchell writes:
>>uses a TXT record with a hash of the client ID as a key so that it
>>knows if it is allowed to delete an A record.
>	What would happen if I generated a fake TXT record with 17
>randomly-chosen digits such that a hex dump looks like what one sees
>in a TXT record?  The record wouldn't work at all, but in this case, I
>don't want dhcpd to ever get talked in to removing that record.
>	Would the bogus .TXT record cause any unexpected harm
>Martin McCormick
No need to create a bogus TXT record, as the *lack* of such a record
prevents the deletion. The dhcpd dynamic dns update has a yxrrset
included with it which means "this other record must exist before
deleting". The nsupdate man page (part of bind not dhcpd) gives some
examples of yxrrset and nxrrset features.

I'd pursue other lines of investigation, as I think that it may just be
coincidence that dhcpd deleted a record at about the same time.


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