Mavericks fails Firewall Stealth Mode test, why?

I have firewall selected and also selected "Enabled Stealth Mode" in the Maverick Firewall setting, BUT when I run the SHIELDS UP! Test at http://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?

SandboxGeneral said:

It sounds like you're referring to the software firewall built into OS X, right?

Is the computer you're testing directly connected to your modem? If you're connected to WiFi or to a router via Ethernet, then Shields Up is testing the firewall on the router and not OS X.

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Yes the firewall in Maverick found in Sys Pref.

My Mac is connected to the router via wireless. Yet I tired with ethernet, same thing, FAILS the Stealth test at Shields up!

mmomega said:

Did you try connecting your computer directly to the modem with no router in between?

Since you have a router Shields Up isn't really going to tell you much of anything because it's not scanning your computer, it's scanning your router, unless you've explicitly told the router to forward all incoming packets to your Mac.

Shields Up was useful back when everyone had their machine connected directly to the internet via a direct connection to a dialup/dsl/cable modem. With the prevalence of routers these days its usefulness is limited since it's not actually telling you anything about your computer as it's the router that is actually being scanned.

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My Mac connects to the modem, and modem is plugged into wall socket. I don't have a "Router" then it seems, only a Modem.

Thanks for your reply, I think I understand now

It gives a perfect stealth report when I put on firewall in modem, yet the problem is when I do that my Xbox cannot connect to Xbox live