Ping uses ICMP which by its nature is insecure but if a router or firewall is set to accept a certain amount of pings its considered secure there is alot more to cracking a system than pinging ,A bit of personal advice this guy you speak of might be an excellent technician but not know much about security the best way to learn security is tutorials or books and playing with systems your self .Before i learned security i was told by a good pc analyst that unix was an unbreakable os ,I soon learned that was a Lie


Peace EviL