Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!att!linac!linac!palkovic
From: palkovic@zippy.fnal.gov (John A. Palkovic)
Newsgroups: comp.unix.questions
Subject: Re: Hostname from Internet address?
Message-ID: <PALKOVIC.90Dec26231910@zippy.fnal.gov>
Date: 27 Dec 90 04:19:10 GMT
References: <1990Dec25.070328.4413@msuinfo.cl.msu.edu>
Reply-To: palkovic@linac.fnal.gov
Organization: Bob's School of Quantum Mechanics
Lines: 33
In-Reply-To: raja@bombay.cps.msu.edu's message of 25 Dec 90 07:03:28 GMT

In article <1990Dec25.070328.4413@msuinfo.cl.msu.edu> 
	raja@bombay.cps.msu.edu (Narayan S. Raja) writes:

   Given a hostname (e.g. zip.foo.bar.edu), one
   can use a network information program like
   nslookup to find its Internet address.  How
   about the other way round?  Given an internet
   address (e.g. 1.2.3.4), how would one find the 
   complete hostname?

I use the following shell script. You may have to tweak the args to
sed or the sleep command.

#!/bin/sh
#
# Map an IP address to a host name
#
OIFS=$IFS
IFS=.
set -- $1
IFS=$OIFS
PTR=`echo $4.$3.$2.$1.in-addr.arpa`
(
  echo set q=ptr
  sleep 1
  echo $PTR
) | nslookup | sed -e 1,3d -e 's/^.*> //'


--
John Palkovic (708) 840-3527	| palkovic@linac.fnal.gov
"A Superconductor generates electricity without resistance when cooled." 
- Chicago Tribune, Oct. 21, 1990, A-18