A common step in troubleshooting connectivity problems is to use the Ping tool to ping the IP address of the computer to which you are trying to connect. When you ping, you send an ICMP Echo message (also known as an ICMP Echo Request message) and get an ICMP Echo Reply message in response. By default, Windows Firewall does not allow incoming ICMP Echo messages and therefore the computer cannot send an ICMP Echo Reply in response. To configure Windows Firewall locally to allow the incoming ICMP Echo message, you must enable the Allow incoming echo request setting in the ICMP dialog box, available from the ICMP settings on the Advanced tab of the Windows Firewall component of Control Panel. The following figure shows an example.
You can also enable incoming ICMP Echo messages for a specific connection from the ICMP tab of the Advanced Network Settings for a selected connection, available from the Advanced tab of the Windows Firewall component of Control Panel.
If your computer is part of a managed network, then you can also configure ICMP exceptions as part of Windows Firewall Group Policy settings. For more information, see Deploying Windows Firewall Settings for Microsoft Windows XP with Service Pack 2.
Note Only local administrators can change Windows Firewall settings, unless overridden or prohibited by Windows Firewall Group Policy settings.
Enabling incoming ICMP Echo messages will allow others to ping your computer. However, it also leaves your computer vulnerable to the types of attacks that use ICMP Echo messages. Therefore, it is recommended that you enable the Allow incoming echo request setting temporarily, and then disable it when it is no longer needed.
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