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Date: Sun, 30 Mar 2003 10:47:54 -0700 (MST)
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To: des@ofug.org
From: "M. Warner Losh" <imp@bsdimp.com>
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cc: arch@freebsd.org
Subject: Re: Allow underscores in DNS names
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In message: <xzpel4phrcs.fsf@flood.ping.uio.no>
            des@ofug.org (Dag-Erling Sm=F8rgrav) writes:
: "M. Warner Losh" <imp@bsdimp.com> writes:
: > True.  However, they are still relevant today.  '_' is illegal in D=
NS
: > names
: =

: Says the RFC.  IIRC, BIND traditionally did not enforce this, though
: it does now for A records in master zones unless you change the
: "check-names" setting (it seems to allow it for TXT records though).

Bind 4 didn't enforce this until about 1998 or so.  Like I explained
in the other post, the reason it was changed was so that bind would
only accept welll formed packets so that it could help reduce the
liklihood that one could write an 'egg' for the payload for a buffer
overflow.  Bind 8 and bind 9 do enforce it for those RR that it is
well defined.  TXT records are well defined as allowing anything in
them.

Warner