CWA

Publishing Communicator Web Access (CWA) with Forefront Threat Management Gateway 2010

In my previous post I outlined configuring Forefront TMG 2010 to publish the OCS 2007 R2 web components. Please see that post for basic installation instructions and network configurations.

In this post, I will outline publishing Communicator Web Access (CWA) to the internet using Forefront TMG 2010.

DNS Records and Certificate Requirements

First lets cover the new DNS records and certificate entries required for communicator web access. With the addition of desktop sharing to CWA, additional DNS records and certificate entries are required to provide that functionality.

The following DNS records are required for CWA:

DNS Record

Usage

Record Type

cwa.domain.com

CWA Access

A record

as.cwa.domain.com

CWA Desktop Sharing

CNAME to cwa.domain.com

download.cwa.domain.com

CWA Desktop Sharing

CNAME to cwa.domain.com

Your certificate will need to have all of the names above on it.

In my environment I have the following certificate information:

Common Name: cwa.winxnet.com

Subject Alt Name(s): as.cwa.winxnet.com download.cwa.winxnet.com

CWA Web Site Configuration

In my example I have two web sites configured on the CWA server. One for internal access and one for external access. When you create virtual servers for CWA you have two options for site types, Internal and External. The only difference is authentication type. Internal sites will let you choose NTLM authentication, which allows for simple access from inside the corporate network on domain joined machines. External sites will use Forms-Based Authentication, or Custom Authentication. Custom authentication can be used to perform two factor authentication with services like RSA or other smart card/pin authentication methods.

In our example our Internal site will be a standard internal site listening on port 443. Our external site however will run on port 4443, and we will perform bridging with the forefront TMG server to give users access to this site.

I will outline creating the external web server, assuming an internal web server has been configured listening on port 443.

First, open the Communicator Web Access management console, this is separate from the OCS 2007 R2 primary admin console, but is included when you install the admin tools on any machine.

Right click on the server name and choose Create Virtual Web Server.

image The first splash screen just gives basic information about requirements for this task, just hit Next.

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At the next window, this is where you will choose your web server type, choose External.

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The next window allows you to choose your authentication types. If you were using a third party authentication method you would specify it here. Although it says in the description that the built in windows integrated and forms-based authentication will be used, the external web site will only allow Forms-Based Authentication.

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The next window confirms those authentication settings, notice NTML is grayed out.

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The next screen has you specify an SSL certificate to be used with the https requests. You can choose HTTP if you are using an SSL Accelerator device, but you cannot use CWA over HTTP without such a device.

Choose the certificate you created with all the necessary name entries and hit Next

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The next screen has you specify the IP address and port the web site will listen on. If you have an additional IP address you can use port 443 with a separate IP than your internal server. In our example, I will be using a single IP address and utilizing bridging with Forefront TMG, so I will enter the port as 4443.

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On the next screen, enter a name to identify the external web site such as CWA External.

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The next screen has you specify a port to listen to OCS traffic. This is seperate from the web site listening settings. This port is really important if you are collocating OCS Services, or even in this case where we have multiple CWA virtual servers on the same server. This port really does not matter, as long as it does not conflict with another port on the same server used for OCS Traffic. In my case I am entering 5071, my internal server listens on 5070.

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At the next screen you must specify a Next Hop Pool, this drop down will display all the pools in your environment and allow you to choose a pool and listening port. In my case our poolname is ocs.winxnet.com.

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Hit Next twice to confirm your settings for the new virtual server, the wizard will create the virtual directory and start the web site for you. As with all of the OCS installations, a log is available at the end for success and failure.

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Now review your two sites, a screenshot of how the site summary should display is below.

imageTest access to your web site on the port you specified during setup, and you should see a form to login because we chose External for the site type.

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Now that the OCS configuration is complete, we will configure Forefront TMG Web Site Publishing rules to allow traffic to your CWA services.

Forefront TMG 2010 Configuration

My last post reviewed networking configurations for this Forefront server. You can get away with a single External/DMZ IP address for all of these services if you have a single certificate with all of the names. In my case I have multiple certificates, so another IP address will need to be assigned to the DMZ network card on my Forefront TMG 2010 server.

Once you have added your external IP address, and imported the certificate used on your web server; (See my last post for instructions on both of these steps). We will now create the web site publishing rule for CWA.

Right click on Firewall Policy and choose New->Web Site Publishing Rule.

imageOn the New Web Publishing Rule Wizard first page, enter a name for your rule like CWA. Hit Next.

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For a rule action, choose Allow. Hit Next

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For the Publishing Type choose Publish a single web site or load balancer. Hit Next.

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For Server Connection Security choose Use SSL to connect to the published Web server or server farm. Hit next.

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For your internal site name, you will want to specify the same Internal/External site name, whatever is the common name on your certificate, in my case it is cwa.winxnet.com.

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If you cannot resolve the name correctly from the TMG server, or want to specify a different computer to connect to for that name, you can do so by specifying a computer name or IP Address.

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Once you have made the necessary entries, hit Next.

For internal publishing details, under path type /* to allow all sub directories required by CWA. Hit Next.

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Under Public Name Details enter the public name for your site, and hit Next. In my case it is cwa.winxnet.com.

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On the next page to specify a web listener, choose New.

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In the new web listener wizard first page, enter a name for the listener like CWA.

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For Client Connection Security choose Require SSL secured connections with clients.

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On the Web Listener IP Address page, select the check box next to External, highlight external and choose Select IP Addresses… On this next page, specify the IP address you set aside for CWA.

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Hit Next, on the next page for Listener SSL Certificates, highlight the IP Address selected on the last page and choose Select Certificate… Choose your valid certificate and choose Select. Hit Next.

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For Authentication settings, choose No Authentication.

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Because we chose No Authentication, we have no SSO options, just choose Next.

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Review the settings for your listener and hit Finish.

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With your listener selected from the drop down menu, hit Next.

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For Authentication Delegation choose No Delegation, but client may authenticate directly. Hit Next.

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Leave the default settings for User Sets and hit Next.

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On the next page, select Test Rule to verify all rule settings are correct. If the result is OK, hit close, then select Finish.

Make sure to Apply your settings to the Forefront TMG server before continuing.

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If you had a separate IP address for you internal site, and your external site you do not need to do the next step. This next step will configure bridging to direct our user request to port 4443 for this external virtual server.

Right click on your CWA rule and choose Properties.

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On the Properties page, select the Bridging tab.

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Where it says Redirect requests to SSL port, enter port 4443, or whatever port you specified during your website configuration. Hit OK.

Again, apply your changes before continuing.

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You can test the rule again from the Properties page. Simply open the Properties page for the rule and Test Rule will be an option there. If the test returns OK, continue to test your site from a computer outside the network.

Testing and Known Issues

You can test access to this site from Internet Explorer outside the network, you should simply be able to specify the https:// URL of your site, and TMG 2010 will handle bridging the request to the correct virtual server on the CWA server. You can also use CWA for access to a great IPhone OCS App called iDialog by Modality Systems.

A very common known issue for CWA configurations is receiving the error Cannot sign in because your computer clock is not set correctly or your account is invalid.  (Error Code: 0-1-492)

This is an easy fix, and has to do with Service Principal Name (SPN) settings for the CWA Site.

To fix this issue, simply add the correct SPN to your CWA Service Account. This is the account specified during CWA installation to run the service.

You can modify this setting using ADSI Edit, and looking for the attribute servicePrincipalName.

imageEnter the SPN for your site in the form http/cwa.winxnet.com where cwa.winxnet.com is your internal or external FQDN of the site.

I also blogged before about my experiences when load balancing CWA.

Other than those two instances, this configuration is pretty straight forward and just works.

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Posted on by Randy Wintle in CWA, Forefront TMG 2010, Load Balancing, OCS, OCS 2007 R2, Server 2008 R2, Unified Communications 11 Comments

Collecting OCS Performance Data For PSS

It has been a while since I have had a post over here, guess you can blame the holiday season as well as the busy beginning of the year at Winxnet. Anyways, I have been working with PSS on an issue with external live meeting through the edge for quite some time now, and with that has been lots of performance monitor collection, after clicking through all of the different collectors multiple times, I decided to create some templates to have for future use and wanted to share them. Its nothing special, no awesome script or anything complicated, but a very basic tool that may be useful to anyone going forward.

http://cid-389bd51b03b1f8f9.office.live.com/embedicon.aspx/Public/Performance%20Monitor%20Templates
Above is a link for access to these files on my sky drive. If you have any issues accessing these please leave a comment or contact me via email and I will get them to you.

They are very easy to use, once downloaded, open Reliability and Performance Monitor from either your Front End or Edge Server…

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Expand “Data Collector Sets” and right click on the User Defined folder. Choose New->Data Collector Set

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Name the collector set whatever you would like and make sure to choose Create from a template.

Click next to access the next page in the configuration wizard. Choose Browse and locate the XML file you downloaded containing the template information. Once you select that file the page should look like this:

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The next two screens will ask you where to save this file, I would suggest a drive with plenty of space as these can get very large depending on the amount of traffic on your server and how long they are running.

 

When you are ready to collect data simply right click on the set you created and choose start.

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Once you are ready to analyze data, or send to Microsoft PSS for data analysis you simply choose stop, and you will have a file in the location you specified. Microsoft PSS uses a tool called PAL(Performance Analysis of Logs) which is an open source application written by a Microsoft employee. This tool can be found here:  http://www.codeplex.com/PAL If you are feeling up to performing some of your own analysis this is a great tool to use. I may try to post some more detailed information on using this tool soon.

 

The templates included in my link include the following Counters:

 

Logical Disk

Memory

Network Interface

Objects

Paging File

Physical Disk

Process

Processor

TCPv4

Thread

All <LC: > Counters

 

Hopefully soon I will have a new post describing the fix for this strange live meeting issue, until then, Enjoy!

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Posted on by Randy Wintle in Audio/Video MCU, Conferencing, Edge, Live Meeting, Load Balancing, Microsoft, OCS, OCS 2007 R2, Unified Communications 5 Comments

CWA Error through F5 Load Balancer: Your Connection was ended. Please Sign in Again. (Error Code: 0-1-482)

 

On a recent deployment we deployed CWA internally and externally using ISA Server 2006. The customer decided they wanted to provide high availability to the CWA service, so we introduced a hardware load balancer to provide that functionality. After we set the two servers with identical site settings behind the load balancer we started having users receive this error when connecting to the CWA site:

cwaerror1

At first glance deploying CWA through a load balancer would seem pretty basic, they are websites you access over https, however there is some key information in the R2 Documentation for deploying CWA behind a load balancer. http://technet.microsoft.com/en-us/library/dd441196(office.13).aspx

Communicator Web Access supports most hardware load balancers, provided that the load balancer:

  • Allows you to set the TCP idle timeout to 1,800 seconds (30 minutes). The TCP idle timeout represents the amount of time the server will wait for information during a session. If you are using a reverse proxy server (such as Microsoft Internet Security and Acceleration Server) then the TCP idle timeout on that computer should also be set to 1,800 seconds.
  • Allows you to use a source network address translation (SNAT) pool if you need to handle more than 65,000 simultaneous connections. SNAT is designed to "hide" multiple servers behind a single IP address (that is, a number of servers can be accessed using just one IP address). With a SNAT pool, servers can be hidden behind multiple IP addresses.
  • Allows you to use cookie persistence when configuring session affinity. With cookie persistence, information about the actual Communicator Web Access server being used for a session is stored in an Internet cookie on the client computer. When configuring the load balancer’s session persistence profile it is recommended that you use "HTTP Cookie Insert." With this configuration method, information about the server to which the client is connected is inserted in the header of the HTTP response from that server as a cookie.

Our issue was related to the persistence profile. When a user connects to CWA they must maintain a connection to the same server as the initial connection or it will not work. The persistence profile, using a HTTP Cookie Insert method will enable this persistence.

We were using an F5 BIG IP LTM Load balancer for this deployment, we actually chose “Source Address Affinity”. Below you can seen a screenshot of the persistence profile used in this configuration.

f5cwaconfig

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tweetmeme_service = ‘bit.ly’;

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Posted on by admin in CWA, F5, Load Balancing, Microsoft, OCS, OCS 2007 R2, Unified Communications 5 Comments