Bash Script to dig a list of IP Addresses

Update: I modified the script.  It now gives you an NA or the PTR when available.  

I had a customer that had some unusual traffic during a given time of the date and we wanted to resolve the destination IP addresses.  I wanted be able to have a list of IP addresses and run a script against them using the dig command.  Here we go.

The Script

#!/bin/bash

IPLIST=$1
while read IP; 
	do
	domain=`dig -x "$IP" +short | head -1`
        if  test -z "$domain" ;
	then
		echo $IP  'N/A'	
	else
		echo $IP  ${domain}
	fi	
	done < "$IPLIST"  >results.csv

The List

177.184.152.24
66.240.205.34
193.57.40.38
179.104.203.79
107.173.194.163
218.211.168.178
23.126.142.209
94.102.57.241
134.209.89.172
185.150.190.103
134.209.89.172
142.93.137.80
188.166.75.140
101.181.167.221

File List

We can see the two files in the folder and that the diggity.sh has the executable permission.  You need to do this by typing chmod +x diggity.sh

The Command

./diggity.sh list.txt

The Results

Here we can see the results.csv file is now present.

The Output

If there is no results, you will not see anything.  I am going to update the script so that it will show the original IP address and the corresponding name in a csv format.