rDNSlookup

rDNSlookup.sh

#!/bin/bash
#
# Copyright (c) 2016 Katsuya SAITO
# This software is released under the MIT License.
# http://opensource.org/licenses/mit-license.php
#
# @(#) rDNSlookup.sh ver.1.0.2 2016.01.29
#
# Usage:
#   rDNSlookup.sh file
#     file: List of IP address, each line has an IP address.
# 
# Description:
#   Looking for a host name from a given IP addresses.
#   Output is like a CSV file style... "IP_Address","FQDN"
#
# 
###############################################################################

# CONFIGER SECTION #----------------------------------------------------------#

readonly DNSV="8.8.8.8"              # DNS Server. Default is Google Public DNS

#-----------------------------------------------------------------------------#

# FUNCTION SECTION #-----------------------------------------------------------

function reverse_dns_lookup() {
  ans=`dig @$DNSV -x $ipaddr PTR +short | sed -e 's/\.$//' 2>/dev/null`
  
  if [ -z "$ans" ]; then
      fqdn="No_HOST"
    else
      fqdn="$ans"
  fi
  return 0
}

function temp_check() {
  count=`grep -c $ipaddr $TEMPFILE 2>/dev/null`
  if [ $count = 0 ]; then
      echo -n "$ipaddr," >> $TEMPFILE
      return 0
    else
      return 1
  fi
}

function cleanup() {
  if [ -e $TEMPFILE ]; then
      rm -f "$TEMPFILE"
  fi
}

function cleanup_error() {
  if [ -e $TEMPFILE ]; then
      rm -f "$TEMPFILE"
  fi
  echo "Any error happend!!"
  exit 1
}

#-----------------------------------------------------------------------------#

# SCRIPTS SECTION ------------------------------------------------------------#

if [ $# != 1 ]; then
    echo "Useage: $0 ipaddresses_file"
    echo "        This scripts need an input file"
    exit 1
fi

TEMPFILE=`mktemp`
trap cleanup EXIT
trap cleanup_error SIGHUP SIGINT SIGTERM

echo "IP_Address,FQDN"

for ipaddr in `cat $1`
do
  temp_check
  if [ $? = 0 ]; then
      reverse_dns_lookup
      echo "$fqdn" >> $TEMPFILE
      echo "$ipaddr,$fqdn"
    else
      echo `grep $ipaddr $TEMPFILE`
  fi      
done
exit 0
#-----------------------------------------------------------------------------#