In a recent post by David Pogue on Apple security, he states
* You can opt to make your Mac invisible to “pings†from the Internet, a common tactic of spammers who are looking for available machines to turn into spam relay stations.
As an Apple fanboy and Windows user at work, this is true for both systems. Unfortunately it is disabled in both systems by default. Here’s how to enable it:
On Mac OS X 10.4:
- Go to System Preferences > Sharing
- Click the Firewall button
- Click Advanced
- Check Enable Stealth Mode
On Windows XP Professional:
- Go to Control Panel > Windows Firewall
- Click the Advanced tab
- Next to ICMP click Settings
- Uncheck the first option “Allow incoming echo request”
This will set both systems to drop any incoming ping request.
Note for Windows XP: The Allow incoming echo request is checked by default if you have File and Printer sharing enabled. To stealth your computer, you need to turn off File and Printer sharing. This is due to the fact that Microsoft Directory Services (Port 445) requires the ability to ping for it to function correctly.
Mac OS X handles this a bit better and allows you to share files and printers without allowing someone to ping it on the local network. But, as the general rule of thumb, the more services you have open, the more vulnerable you are for an attack, regardless if you allow pings or not.