Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!elroy.jpl.nasa.gov!ncar!gatech!uflorida!mlb.semi.harris.com!mintaka.mlb.semi.harris.com!john
From: john@mintaka.mlb.semi.harris.com (John M. Blasik)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: gethostbyaddr() failing
Message-ID: <1990Dec17.162511.5678@mlb.semi.harris.com>
Date: 17 Dec 90 16:25:11 GMT
References: <1990Dec16.191345.22482@engin.umich.edu> <9012170259.AA06606@nsipo.arc.nasa.gov>
Sender: news@mlb.semi.harris.com
Organization: Harris Semiconductor, Melbourne FL
Lines: 20
Nntp-Posting-Host: mintaka.mlb.semi.harris.com

medin@NSIPO.ARC.NASA.GOV ("Milo S. Medin", NASA ARC NSI Project Office) writes:
>
>That's not a bug but a feature!  Late model BIND resolver code has a security 
>feature in it which causes this behavior.  Basically, if your code does
>a gethostbyaddr call to the DNS, the resolver will query the DNS system for
>a PTR record for the address passed to it.  The old code would then return 
>the reply, without verification.  The new code goes one step farther by
>then additionally doing a gethostbyname call on the returned name, and verifying
>the name has the original address as one of the A records associated with it. 

I believe this is a SUNism and would dare call it a bug.

What's wrong with doing the extra gethostbyname only when necessary (in rsh
 and friends)?

The way it works now, things like traceroute and netstat break
(no "A" for FOO.ST.NSF.NET, PTR's returned for host-0 names ala rfc 1101)


-- john