Configuring Networks with ISA Console Network Wizards and ToolsOne of the first tasks that is normally performed on a new ISA Server is the configuration of the networks and the associated network rules. This instructs ISA how to handle traffic and provides a base on which firewall rules can be built. For example, an ISA server with three network adapters that are physically connected to three different networks should configure the networks in the console so that ISA understands what IP addresses should exist on each network and how to handle the traffic that comes from those networks.
Exploring the Networks NodeThe Networks node, illustrated in Figure 3.2, contains configuration settings for Networks Sets and Network Rules and provides wizards that assist in the creation and designation of these elements. The task pane for the Networks node contains three tabs: Tasks, Templates, and Help. Each of these tabs contains specific functionality and wizards related to ISA's network configuration.
Figure 3.2. Viewing the Networks node of the ISA Management Console.[View full size image]
Understanding the Definition of ISA NetworksThe term network in ISA should not be confused with the concept of subnets; the two terms are distinct in the ISA world. An ISA network is defined as the grouping of physical subnets that form a network topology that is attached to a single ISA Server network adapter. So, a single ISA "network" could be composed of multiple physical networks. Take, for example, the diagram illustrated in Figure 3.3. Even though there are eight physical subnets, all connected to each other with switches, routers, and gateways, ISA sees these individual subnets as only two networksan internal network and a perimeter networkbecause it has network adapters attached to only a single subnet on each of the networks. To further illustrate, a uni-homed (single NIC) server would see the range of all IP addresses on the Internet as a single ISA network. This concept is important to understand.
Figure 3.3. Examining ISA network concepts.[View full size image]
Outlining Network SetsA network set is a logical grouping of networks that makes it easier to apply rules and policies to multiple networks at the same time. For example, a rule could be generated to allow web browsing from the All Protected Networks network set. This makes it easier to apply the rule by avoiding creating multiple rules or having to select each individual network for the rule.The following lists the two default network sets and which networks are included in each:All Networks (and Local Host) This network, as the name implies, contains all networks that are designated on the ISA Server, including the Local Host. Any new networks that are created are automatically added to the network set.All Protected Networks The All Protected Networks network set contains all networks except for the External network. As with the previous network set, any new networks are automatically added to this group unless specifically excluded. Network sets can be created from scratch and customized as necessary. For example, it may be useful to create a network set to logically organize all the client networks, to make it easier to set up rules to restrict their access to a server network. To create a custom network set, perform the following steps:
Defining Network TemplatesTo assist with the task of setting up ISA network settings, Microsoft has included a powerful and helpful wizard, the New Network Wizard (see Figure 3.4). The New Network Wizard allows ISA administrators to apply network templates to the ISA Server, which automatically configure the appropriate network sets and rules based on standard settings that are most commonly deployed for the type of network design chosen. For example, a simple ISA server with two network adapters, one connected to the Internet and the other connected to the Internal network, could apply the Edge Firewall template. That template would then configure common settings for this design, such as allowing web access for clients in the Internal network and blocking all inbound traffic from the External network.
Figure 3.4. Creating a new network set.
Exploring Network RulesA network rule in ISA Server is a mechanism that defines the relationship between networks. For example, the network rules defined in Figure 3.5 define how traffic is transmitted between the source and desintation networks. The network rules defined allow VPN clients to be routed to the Internal network, for the Perimeter (DMZ) network to be accessible, and for Internet access from protected client networks to be defined.
Figure 3.5. Examining network rules.[View full size image]
Figure 3.6. Understanding Network Address Translation (NAT).[View full size image]
Running the Network Template WizardISA Server 2004 streamlines the ISA configuration process with the addition of the Network Template Wizard, which automates the creation of networks, network rules, and firewall rules per common deployment scenarios for ISA. The Network Template Wizard, run by clicking on one of the templates in the Templates tab of the Tasks pane, makes it easier to deploy and configure an ISA Server, or at least gives administrators a head start toward configuration of the server.The Network Template Wizard is straightforward to use for the application of a network template. After the template is in place, additional networks can be added, changes to network rules can be made, and any additional customization required can be performed. In the following step-by-step procedure, the New Network Wizard is used to apply a 3-Leg Perimeter network template. The same general approach can be used when applying any of the other templates as well.
|1.||Open the ISA Server Console by clicking on Start, All Programs, Microsoft ISA Server, ISA Server Management.|
|2.||Select the Network Node by clicking on it in the Console tree.|
|3.||Select the Templates tab in the Tasks pane on the right.|
|4.||Click on 3-Leg Perimeter from the list of templates.|
|5.||At the Welcome dialog box, as shown in Figure 3.7, click Next to continue.|
Figure 3.7. Running the Network Template Wizard.
|1.||Ignore the Export dialog box and click Next to continue.|
|2.||At the subsequent dialog box, which allows for the Internal network to be configured, click Add Adapter.|
|3.||Check the box for the NIC that is attached to the Internal network, as shown in Figure 3.8.|
Figure 3.8. Defining the Internal network.
|1.||When finished adding all IP ranges of which the Internal network will be composed, click Next to continue.|
|2.||At the next dialog box, shown in Figure 3.9, add the IP addresses associated with the Perimeter (DMZ) network, using the same process outlined previously. If a different template that did not have a Perimeter network were chosen, this step would be skipped.|
Figure 3.9. Defining Perimeter network IP address ranges.
|3.||Click Next when finished adding IP addresses to the Perimeter network.|
Figure 3.10. Selecting a firewall policy.
|1.||Choose a firewall policy from the options, using the criteria listed as a guideline. Click Next to continue.|
|2.||Review the options on the completion dialog box and click Finish to create and apply the template, network rules, and firewall rules.|
|3.||Click the Apply button that appears in the upper portion of the Central Details pane, as shown in Figure 3.11.|
Figure 3.11. Applying firewall changes.[View full size image]
|4.||Click OK at the configuration confirmation dialog box.|