System Level Filtering

WARNING:  

The System Tab settings are for advanced users only. If any are incorrectly changed for your system or network, it could result in your firewall not working as expected.

Figure 28
Options Dialog Box (System Tab)

The System tab of the NCF Options dialog box includes the following settings:

LAN Settings---Lets you change the settings for your local area network (LAN) and NetBIOS protocol and lets you add or remove trusted IP ranges. NetBIOS is what Windows uses as the protocol for transferring shared files between computers or printers on a network. NetBIOS is useful on a LAN with trusted computers, but it can leave your computer open to attack if it is allowed for general Internet connections.

ICMP---Lets you specify the types and directions of ICMP messages allowed. We recommend that you do not change the ICMP settings unless you are certain that you are making the right changes. The Default button in the ICMP Settings dialog box resets all the ICMP settings to what they were when NCF was first installed.

Answer Type---Switches stealth mode on or off. Normally, when your computer receives a connection request from another computer, it lets that computer know that this port is closed. In stealth mode, your computer will not respond, making it seem like it is not turned on or not connected to the Internet. We recommend that you keep NCF in stealth mode unless you have some very good reason not to.

Global Application and System Rules---Lets you specify global rules for each of the following:

You can also create system rules by clicking the Settings button; this is very similar to how application-based rules are created. (See Creating Rules for Applications.)