What is my IP?

Lets say that you have a linux machine in a location with non static IP address but you need to access it from outside.

The following script is a quick way to avoid using a dynamic dns service. You can schedule it in a cron job and it will sent you an e-mail with the new IP address if it is changed:

#!/bin/bash
OUTSIDE_IP=$(dig +short myip.opendns.com @resolver1.opendns.com)
LAST_IP=$(cat /root/last_ip.txt)
if [ "$OUTSIDE_IP" != "$LAST_IP" ]
 then
 echo "OUTSIDE_IP has changed"
 echo $OUTSIDE_IP > /root/last_ip.txt
 echo "$OUTSIDE_IP" | mail -s "IP address is changed" username@company.com
fi
echo "`date +%Y-%m-%d\ %T` $OUTSIDE_IP" >> /root/last_ip.log