Is there a script/package which can check the external IP on regular basis and send the changes to an email?
Is the host name consistent? If so, you can just do a dns lookup. If the host name changes with the IP, then that won't work. Another possibility, is a dynamic dns server, which many firewall/routes can be configured to use.
Here's a script that I made that at first I ran every 12 hours at my house. Until I made the script below that runs hourly. Also worth noting is that this stuff is running on RedHat 7.x #!/bin/sh FILE2=`echo "/fwlog/ifconfig.txt"` touch /fwlog/ifconfig.txt ifconfig eth0 | grep inet | awk -F: '{print $2}' | sed 's/Bcast//' > /fwlog/ifconfig.txt mv -f /fwlog/ifconfig.txt $FILE2 cat $FILE2 | mail -s"IP address, ifconfig" email@gmail.com I have another script that checks the ip and only sends an email if it's changed. This may be better for you. This runs hourly. #!/bin/sh ifconfig eth0 | grep inet | awk -F: '{print $2}' | sed 's/Bcast//' > /etc/fw/ipcheck I=`cat /etc/fw/ip` #IP2=`cat /etc/fw/ipcheck` P=`cat /etc/fw/ipcheck` #echo "My ip is $IP1" #echo "My ip is $IP2" if [ "$I" != "$P" ]; then /etc/./ipshow /etc/fw/./fw rm -rf /etc/fw/ip cp /etc/fw/ipcheck /etc/fw/ip #echo "My ip is $I" #echo "My ip is $P" #else #exit 0 fi