Tuesday, February 10, 2015

KEMP Series: How to Restrict Exchange Admin Center Access From the Internet Using KEMP VLB

This is part five in a series of articles detailing load balancing for Exchange using the KEMP virtual load balancer (VLB). In this article I will explain how to restrict Exchange Admin Center (EAC) access from the Internet using KEMP LoadMaster.

The other articles in this series are:
My first article explains the basics of load balancing and how to download a free copy of KEMP Virtual Load Master for your home lab. I'll assume you've already configured it for Layer 7 load balancing.
Note: Since the following procedures rely on SubVSs and traffic inspection, this configuration will only work with Layer 7 load balancing. Layer 4 load balancing cannot inspect traffic and therefore cannot be used to deny access to the EAC.
The Exchange Admin Center (EAC) is the web-based management console used to manage your Microsoft Exchange Server 2013 infrastructure. As such, some customers want to block EAC access from the Internet.

The EAC is part of the ECP virtual directory and is the same virtual directory used in OWA to manage user settings, such as Out of Office settings. If you were to disable or not publish the entire ECP virtual directory to the Internet in order to block EAC access, it would prevent external users from accessing many settings from OWA.
Update: Microsoft just released a new article, Configuring Multiple OWA/ECP Virtual Directories on the Exchange 2013 Client Access Server Role, which describes how to create a separate vDir for the Exchange Admin Center. If you chose the Microsoft solution to disable Internet access to EAC (and I do, if you want Microsoft support) know that you need to follow those step EXACTLY and you will need to redo that setup after every CU. If you wish to load balance the new vDir you will also need to create new SubVSs on the KEMP LoadMaster.
Let's get started configuring EAC restrictions on the KEMP LoadMaster. Log into the LoadMaster with the bal account and navigate to Rules & Checking > Content Rules.

Add each of the following five rules. Be careful to copy and paste each rule entirely and name them "EAC_Block_1-5":




To do this click the Create New button and enter the new rule name (i.e., EAC_Block_1). Paste the first rule string above into the Match String field and click the checkboxes for Ignore Case and Fail on Match. Then click the Create Rule button.

 Repeat for each of the rules above. Your rule list should now look like this:

Now expand Virtual Services > View/Modify Services and click Modify for the Exchange 2013 virtual service. Click the Add New button under SubVSs. You will see a new SubVS at the bottom of the list. Click the rule None and add the EAC_Block_1 rule to the new SubVS. Be sure to click the Add button to add it. Repeat for each of the five EAC_Block rules.

Click <-Back and then click the Modify button for the new SubVS. Name the SubVS Block EAC and click the Set Nickname button.

Expand Advanced Properties and set the Error Code to 401 Unauthorized. There is no need to enter any real servers for this SubVS.

Click <-Back and then expand Advanced Properties for the Exchange 2013 virtual service. Click the Rule Precedence button for Content Switching. You will see a list of all the rules. Click the Promote buttons to move the five EAC_Block rules so they are at the top of the list.

Now when if you try to access the Exchange Admin Center using the KEMP load balancer VIP you will still be able to logon, but cannot access any of the EAC administration parts.

End users will still be able to access their ECP settings from OWA.

If you want to access the EAC internally, simply use the FQDN of one of your CAS servers to bypass the KEMP load balancer. Alternatively, you can configure another virtual service for internal load balancing that does not use the blocking rules.

This concludes my series on configuring the KEMP virtual LoadMaster. I hope you found these articles useful.

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