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Windows Firewall

  • Configure Windows Firewall

Because most computers are connected to the Internet through dialup, broadband (such as DSL or cable modems), or a local area network (LAN), computers are vulnerable to attack or unauthorized access. To help protect your system, you should have a firewall between you and the outside world. The firewall monitors all traffic coming in and going out to prevent unauthorized access.

Windows Firewall is a packet filter and stateful host-based firewall that allows or blocks network traffic according to the configuration. A packet filter protects the computer by using an access control list (ACL), which specifies which packets are allowed through the firewall based on IP address and protocol (specifically the port number). A stateful firewall monitors the state of active connections and uses the information gained to determine which network packets are allowed through the firewall. Typically, if the user starts communicating with an outside computer, it remembers the conversation and allows the appropriate packets back in. If an outside computer tries to start communicating with a computer protected by a stateful firewall, those packets are automatically dropped unless granted by the ACL.

Firewall rules that can be defined include

  • Inbound rules: These rules help protect your computer from other computers making unsolicited connections to it.
  • Outbound rules: These rules help protect your computer by preventing your computer from making unsolicited connections to other computers.
  • Connection-specific rules: These rules enable a computer's administrator to create and apply custom rules based on a specific connection.

Basic Configuration

Windows Firewall is on by default. When Windows Firewall is on, most programs are blocked from communicating through the firewall. If you want to unblock a program, you can add it to the Exceptions list (on the Exceptions tab). For example, you might not be able to send photos in an instant message until you add the instant messaging program to the Exceptions list.

To turn on or off Windows Firewall:

  1. Open Windows Firewall by clicking the Start button, clicking Control Panel, clicking System and Security, and then clicking Windows Firewall.
  2. In the left pane, click Turn Windows Firewall on or off, as shown in Figure 7.4. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
    Figure 7.4

    Figure 7.4 Windows Firewall.

  3. Below each network location type, click Turn on Windows Firewall, and then click OK. It is recommended that you turn on the firewall for all network location types.

Besides turning the firewall off and on for each profile, you also have the following options:

  • Block all incoming connections, including those in the list of allowed programs: This setting blocks all unsolicited attempts to connect to your computer. Use this setting when you need maximum protection for your computer, such as when you connect to a public network in a hotel or airport, or when a known computer worm is spreading over the Internet. With this setting, you aren't notified when Windows Firewall blocks programs, and programs in the list of allowed programs are ignored. When you block all incoming connections, you can still view most web pages, send and receive email, and send and receive instant messages.
  • Notify me when Windows Firewall blocks a new program: If you select this checkbox, Windows Firewall informs you when it blocks a new program and gives you the option of unblocking that program.

The first time you connect to a network, you must choose a network location (sometimes known as profiles). This automatically sets the appropriate firewall and security settings for the type of network that you connect to. If you connect to networks in different locations, such as work, home, or your favorite coffee shop or hotel, choosing a network location can help ensure that your computer is always set to the appropriate security level. See Figure 7.5.

Figure 7.5

Figure 7.5 Setting Network Location in Windows Firewall.

Traditionally with firewalls, you can open or close a protocol port so that you can allow or block communication through the firewall. With the Windows Firewall included with Windows 7, you specify which program or feature you want to communicate through the firewall. The most common options are available by clicking the Allow a program or feature through Windows Firewall option, as shown in Figure 7.6. If you need to open a port instead of specifying a program, you have to use the Windows Firewall with Advanced Security.

Figure 7.6

Figure 7.6 Allow programs to communicate through Windows Firewall.

In addition to the notification setting available (configured by clicking Change notification settings) when you turn Windows Firewall on or off, you can display firewall notifications in the taskbar for three different behaviors:

  • Show icon and notifications: The icon always remains visible on the taskbar in the notification area and notifications are displayed.
  • Hide icon and notifications: The icon is hidden and notifications aren't displayed.
  • Only Show notifications: The icon is hidden, but if a program needs to show a notification, it shows a notification balloon on the taskbar.

Notifications are also displayed in the Action Center in Control Panel.

Windows Firewall with Advanced Security

The new Windows Firewall with Advanced Security is a Microsoft Management Console (MMC) snap-in that provides more advanced options for IT professionals. With this firewall, you can set up and view detailed inbound and outbound rules and integrate with Internet Protocol Security (IPsec). To access the Windows Firewall with Advanced Security, follow these steps:

  1. Open Administrative Tools by clicking the Start button, clicking Control Panel, clicking System and Security, and then clicking Administrative Tools.
  2. Double-click Windows Firewall with Advanced Security, as shown in Figure 7.7. If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Figure 7.7

Figure 7.7 Windows Firewall with Advanced Security console.

You can also access the Windows Firewall with Advanced Security by clicking the Advanced settings option in the Windows Firewall screen. Of course, you must be a member of the Administrators group to use Windows Firewall with Advanced Security.

The Windows Firewall with Advanced Security management console enables you to configure the following:

  • Inbound rules: Windows Firewall blocks all incoming traffic unless solicited or allowed by a rule, as shown in Figure 7.8.
    Figure 7.8

    Figure 7.8 Inbound rules.

  • Outbound rules: Windows Firewall allows all outbound traffic unless blocked by a rule.
  • Connection security rules: Windows Firewall uses a connection security rule to force two peer computers to authenticate before they can establish a connection and to secure information transmitted between the two computers. Connection security rules use IPsec to enforce security requirements.
  • Monitoring: Windows Firewall uses the monitoring interface to display information about current firewall rules, connection security rules, and security associations.

You create inbound rules to control access to your computer from the network. Inbound rules can prevent

  • Unwanted software being copied to your computer.
  • Unknown or unsolicited access to data on your computer.
  • Unwanted configuration of your computer from remote locations.

To configure advanced properties for a rule using the Windows Firewall with Advanced Security, do the following:

  1. Right-click the name of the inbound rule and then click Properties.
  2. From the properties dialog box for an inbound rule, configure settings on the following tabs:
    • General: The rule's name, the program to which the rule applies, and the rule's action (allow all connections, allow only secure connections, or block).
    • Programs and Services: The programs or services to which the rule applies.
    • Computers: The computers that can communicate through the firewall.
    • Users: The users that can communicate through the firewall.
    • Protocols and Ports: The rule's IP protocol, source and destination TCP or UDP ports, and ICMP or ICMPv6 settings.
    • Scope: The rule's source and destination addresses.
    • Advanced: The profiles or types of interfaces to which the rule applies.

You can also use the Windows Firewall with Advanced Security to create outbound rules to control access to network resources from your computer. Outbound rules can prevent

  • Utilities on your computer from accessing network resources without your knowledge.
  • Utilities on your computer from downloading software without your knowledge.
  • Users of your computer from downloading software without your knowledge.

Computer Connection Security Rules

Because the Internet is inherently insecure, businesses need to preserve the privacy of data as it travels over the network. Internet Protocol Security (IPsec) creates a standard platform to develop secure networks and electronic tunnels between two machines. The two machines are known as endpoints. After the tunnel has been defined and both endpoints agree on the same parameters, the data is encrypted on one end, encapsulated in a packet, and sent to the other endpoint where the data is decrypted.

In Windows XP and Windows Server 2003, you configure the Windows Firewall and IPsec separately. Unfortunately, because both can block or allow incoming traffic, it is possible that the Firewall and IPsec rules can conflict with each other. In Windows 7, Windows Firewall with Advanced Security provides a single, simplified interface for managing both firewall filters and IPsec rules.

Windows Firewall with Advanced Security uses authentication rules to define IPsec policies. No authentication rules are defined by default. To create a new authentication rule, follow these steps:

  1. In Windows Firewall with Advanced Security, select the Computer Connection Security Rules node.
  2. Right-click the Computer Connection Security Rules node in the console tree and then click New Rule to start the New Connection Security Rule Wizard.
  3. From the Rule Type page of the New Authentication Rule Wizard (as shown in Figure 7.9), you can select the following:
    • Isolation: Used to specify that computers are isolated from other computers based on membership in a common Active Directory domain or current health status. You must specify when you want authentication to occur (for example, for incoming or outgoing traffic and whether you want to require or only request protection), the authentication method for protected traffic, and a name for the rule.
    • Authentication exemption: Used to specify computers that do not have to authenticate or protect traffic by their IP addresses.
    • Server to server: Used to specify traffic protection between specific computers, typically servers. You must specify the set of endpoints that exchange protected traffic by IP address, when you want authentication to occur, the authentication method for protected traffic, and a name for the rule.
    • Tunnel: Used to specify traffic protection that is tunneled, typically used when sending packets across the Internet between two security gateway computers. You must specify the tunnel endpoints by IP address, the authentication method, and a name for the rule.
    • Custom: Used to create a rule that does not specify a protection behavior. You would select this option when you want to manually configure a rule, perhaps based on advanced properties that cannot be configured through the pages of the New Authentication Rule Wizard. You must specify a name for the rule.
    Figure 7.9

    Figure 7.9 Specifying a new connection security rule.

To configure advanced properties for the rule, do the following:

  1. Right-click the name of the rule and then click Properties.
  2. From the properties dialog box for a rule, you can configure settings on the following tabs:
    • General: The rule's name and description and whether the rule is enabled.
    • Computers: The set of computers, by IP address, for which traffic is protected.
    • Authentication: When you want authentication for traffic protection to occur (for example, for incoming or outgoing traffic and whether you want to require or only request protection) and the authentication method for protected traffic.
    • Advanced: The profiles and types of interfaces to which the rule applies and IPsec tunneling behavior.

Cram Quiz

  1. Which Windows Firewall profile includes access to homegroups?

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    A.

    Home network

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    B.

    Work network

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    C.

    Public network

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    D.

    Internet network

  2. If you need to configure IPsec, what program would you use in Windows 7?

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    A.

    IPsec Management console

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    B.

    Computer Management console

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    C.

    Windows Firewall with IPsec

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    D.

    Windows Firewall with Advanced Security

Cram Quiz Answers

  1. A is correct. The Home network location or profile is for home networks or when you know and trust the people and devices on the network. Network discovery is turned on for home networks, which enables you to see other computers and devices on the network. Answers B and C are incorrect because they have access to homegroups disabled. Answer D is incorrect because the Internet network is not a valid network location or profile.
  2. D is correct. The Windows Firewall with Advanced Security enables you to fine-tune the Windows Firewall and configure IPsec. Answer B is incorrect because you cannot configure IPsec with the Computer Management console. Answers A and C are incorrect because these consoles do not exist.
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