Security Tip: Most routers and firewalls allow you to block incoming "Ping" and "Traceroute" packets. This will prevent outsiders from discovering the computing resources on your local networks.

When attempting to block Ping and Traceroute as described above, look for references to "ICMP" (the "Internet Control Message Protocol") in the menus offered by your router or firewall appliance. All conventional Ping and Traceroute packets use ICMP, so if you can configure your equipment to ignore incoming ICMP packets, you'll be immune from that kind of probing.