WUI with Centralized Management
The ESA supports a secure, robust Centralized Management (CM) feature to synchronize changes across multiple appliances without any additional software or hardware. We’ll discuss CM further in Chapter 13, “Multiple Device Deployments,” but because it affects what you’ll see in the WUI, an introduction is in order here. A set of ESAs using CM to manage settings is referred to as a cluster. CM organizes the ESA configuration into a hierarchy: There are machine-specific settings like IP addresses and hostnames, and there are cluster-wide settings like anti-spam policy. In between, you can create logical CM groups of ESAs and specify settings that are configured per group. For example, you might have groups named East and West and have separate DNS server settings for each group.
When using the ESA CM features, the WUI changes to reflect the fact that the ESA is a member of a cluster. At the top of each page, below the menu bar, there are some additional options, and a drop-down box to select the cluster mode. The mode refers to the level in the hierarchy that you’re currently configuring: machine, group, or cluster.
Figure 4-8 shows an example of the WUI where the ESA is a member of the cluster.
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Figure 4-8. Cluster Mode in the WUI
Whenever you’re in a cluster, the WUI attempts to guide you toward the correct mode. For example, if you’re on the Network à IP Interfaces page, the WUI will tell you that the settings are at machine level. If you’re in Cluster or Group mode, the settings are grayed out until you change to Machine mode.
Selecting Cluster Mode
When you are configuring an ESA that’s part of a cluster, you’ll likely find that you need to change the configuration mode often. The WUI makes this easy. Every page offers a mode drop-down box to select cluster, group, or machine mode. You can even select Machine mode for a different ESA, all from the same login, except for Reporting and Monitoring pages, which are only available for the ESA you’re currently logged into. Take care with this feature, however, and always be sure you know which ESA you’re currently configuring. The ESA that you logged into is displayed in the far upper-right hand portion of the WUI. The ESA machine mode that you’re currently in is displayed in the CM options box below the main menu.
To change mode, simply select it from the drop-down, as shown in Figure 4-9.
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Figure 4-9. Centralized Management Mode Selection
If you arrive at a page that is not configured at the mode you’re in, you’ll see a preview of the settings grayed out, as shown in Figure 4-10.
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Figure 4-10. Centralized Management Preview Screen
If you want to change how a particular table is configured within the cluster, you can do that right from the WUI.
Modify CM Options in the WUI
You can modify where in the cluster hierarchy a particular feature is configured here in the WUI with the CM controls at the top of the page.
Figure 4-11 shows an example. I’m changing the way DNS is configured in the CM hierarchy, by moving the settings from cluster level (which is the default) to group level. This is a common scenario if you have ESAs in more than one physical location, and each location has its own DNS servers. Create a CM group for each location, move the DNS settings to the group level, and make sure the individual machines are members of the appropriate group.
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Figure 4-11. Modifying CM Options for DNS Settings
You can also copy settings from one level to another, but take care—this can be confusing. When a feature is configured at more than one level, the most specific setting wins. For example, if DNS is configured at the cluster and group level, any ESA members of the group will use the group settings for DNS, and the cluster settings will be ignored.
Modifying Cluster Settings
To modify other cluster settings or to add or remove machines from the cluster, you need to use the CLI clusterconfig command. Another useful CLI command, for troubleshooting cluster communications issues, is the clustercheck command.