Detect or Find Duplicate IP Addresses

detect_duplicate_ip.sh

#!/usr/bin/env bash

# This script was written for and works on Mac OS X
# I have to use sudo to run arping on Mac OS X
# I believe the options for arping on linux are a little different. I believe you use -D for duplicate IP detection instead of -d but that's from memory and you should check.

echo "Starting duplicate IP detection with sudo arping!"
for i in {1..254};
do
sudo arping -q -d -c 2 192.168.1.$i; [ $? -ne 0 ] && echo "192.168.1.$i duplicate"; 
done

nice @lancelakey! only an idea:

if ! sudo arping -q -d -c 2 192.168.1.$i ; then
echo 192.168.1.$i duplicate
fi

may be more readable than the one liner capturing exit status of the exit status. ifs containing commands still operate on true or false.

Also, maybe do $? -eq 1 or whatever the proper exit code is. I'm just thinking command not found is 127 but would print duplicate.

just ideas.