There are ways to do this by sending logs to a remote syslog server and using third-party tools to scan the firewall log entries. However, be forewarned this will get very old to you very fast (getting alerts/emails for every unwanted firewall access attempt). A normal firewall will see dozens to maybe a few hundred connection attempts per day on the WAN side. Even if you limit the alerts to just a handful of ports, you will soon grow very tired of your email app "dinging" with new mail messages ... ☺ .
I say this in a nice way, "you must be new to firewall administration"... 😀. This is usually the first thing a newly minted firewall administrator thinks he wants until he has it, then he quickly turns it off.
