I have firewall selected and also selected "Enabled Stealth Mode" in the Maverick Firewall setting, BUT when I run the SHIELDS UP! Test at www.grc.com, it FAILS and says: TrueStealth FAILED: Ping Reply: RECEIVED (FAILED) — Your system REPLIED to our Ping (ICMP Echo) requests, making it visible on the Internet. Most personal firewalls can be configured to block, drop, and ignore such ping requests in order to better hide systems from hackers. This is highly recommended since "Ping" is among the oldest and most common methods used to locate systems prior to further exploitation. WHY does the firewall test fail seeing I have selected STEALTH MODE in System Preferences? And what can I do in MAC to get it to PASS?