Xref: utzoo comp.protocols.tcp-ip:14161 comp.protocols.tcp-ip.domains:536
Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!apple!agate!shelby!riacs!nsipo.arc.nasa.gov!medin
From: medin@nsipo.arc.nasa.gov (Milo S. Medin)
Newsgroups: comp.protocols.tcp-ip,comp.protocols.tcp-ip.domains
Subject: Re: gethostbyaddr() failing
Message-ID: <1990Dec18.065356.17961@riacs.edu>
Date: 18 Dec 90 06:53:56 GMT
References: <1990Dec16.191345.22482@engin.umich.edu> <9012170259.AA06606@nsipo.arc.nasa.gov> <1990Dec17.182114.14182@cs.umn.edu>
Sender: news@riacs.edu (James A. Woods)
Reply-To: medin@cincsac.arc.nasa.gov (Milo S. Medin)
Organization: NASA Science Internet Project Office
Lines: 51


What we do here at Ames is that the K-box base address PTR points back to
the K-box, and then each dynamic address has it's own name, and a PTR record
that points back it it.  For example, you have:

n233-edc-gw	IN	A	128.102.18.112
		IN	HINFO	"Kinetics AppleTalk Gateway" "N/A"
n233-edc-1	IN	A	128.102.18.113
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-2	IN	A	128.102.18.114
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-3	IN	A	128.102.18.115
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-4	IN	A	128.102.18.116
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-5	IN	A	128.102.18.117
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-6	IN	A	128.102.18.118
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-7	IN	A	128.102.18.119
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-8	IN	A	128.102.18.120
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-9	IN	A	128.102.18.121
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-10	IN	A	128.102.18.122
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-11	IN	A	128.102.18.123
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-12	IN	A	128.102.18.124
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-13	IN	A	128.102.18.125
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-14	IN	A	128.102.18.126
		IN	HINFO	"AppleTalk Host" N/A
n233-edc-15	IN	A	128.102.18.127
		IN	HINFO	"AppleTalk Host" N/A


The PTR records all point back to the proper names, which are different for
each dynamically assigned address.  It's not that hard to build this with a
shell script or an awk script.  And even if you didn't do this, all that
would happen is the gethostbyaddr would fail.  No big deal, as people shouldn't
be sticking things with dynamically assigned addresses in their .rhosts and the
like.  

No big deal, or perhaps I'm missing something here?  In any case, it's
a big payoff for the security advantages this provides.

						Thanks,
						   Milo