Lync Reverse Proxy Alternatives

Question

When migrating from OCS 2007 to Lync 2010, we balked Microsoft’s recommendation to deploy Forefront Threat Management Gateway (or ISA) just to get the reverse proxy services. 
TMG is way too expensive and complex for such a limited, simple use case.
I didn't find much information on what people are using as free alternatives to ISA/TMG, so I decided to post this discussion in case there are others out there who are interested.
We decided to use Apache 2.2 on Windows Server 2008 R2. 
Here's how we configured it:
Read here to understand what features require a reverse proxy, and follow the steps to configure your FQDNs, Network Adapters and (maybe) obtain an SSL Certificate for the reverse proxy. 
http://technet.microsoft.com/en-us/library/gg398069.aspx
Download and install the latest stable release of Apache with OpenSSL on your reverse proxy server. 
http://httpd.apache.org/download.cgi
We're using the same certificate on the reverse proxy that we use on our front end server (it has the appropriate SANs), so we need to convert it to PEM format for use with Apache:
Use the Certificates MMC on your front end server to export the certificate and include the private key.
Transfer the resultant .pfx file to your reverse proxy server.
Use OpenSSL to convert your .pfx file to PEM:
openssl pkcs12 -in c:\pathto\yourcert.pfx -out c:\pathto\yourcert.pem –nodes 
Separate the private key from the certificate using notepad: 
Open the new .pem file and cut the text from the beginning of the file through the end of the “----END RSA PRIVATE KEY----“ tag. 
Save that text to a new file named
yourcert.key. 
Save
yourcert.pem, which should now only include the certificate.
Copy (or move) the certificate and private key to the Apache configuration directory. We like to use: C:\Program Files (x86)\Apache Software Foundation\Apache2.2\conf\extra\ssl
for storing the certificates.
Edit httpd.conf (typically in
C:\Program Files (x86)\Apache Software Foundation\Apache2.2\conf) to enable and configure the proxy and SSL features:
(See  http://httpd.apache.org/docs/2.2/mod/mod_proxy.html
 for more information on each directive)
Uncomment the following lines, which will enable proxy and SSL:
LoadModule proxy_module modules/mod_proxy.so
LoadModule proxy_http_module modules/mod_proxy_http.so
LoadModule ssl_module modules/mod_ssl.so
Include conf/extra/httpd-ssl.conf
Add the following lines to configure reverse proxy behavior:
#Be a reverse proxy, not a forward proxy
ProxyRequests Off
#Accept requests from any client to any URL
<Proxy *>
Order Deny,Allow
Allow from all
</Proxy>
#Set the network buffer to improve throughput
ProxyReceiveBufferSize 4096
#Configure the Reverse Proxy to forward all requests to your front end server on 4443
ProxyPass / https://yourfrontend.domain.com:4443/
ProxyPassReverse / https://yourfrontend.domain.com:4443/
#Preserve Host Headers for Lync
ProxyPreserveHost On
Optionally, configure logging directives, bindings and server name.
Save and close httpd.conf
Edit httpd-ssl.conf (typically in conf\extra):
Configure the session cache:
Uncomment:
SSLSessionCache “dbm:C:/Program Files (x86)/Apache Software Foundation/Apache2.2/logs/ssl_scache”
Comment out:
SSLSessionCache “shmcb:C:/Program Files (x86)/Apache Software Foundation/Apache2.2/logs/ssl_scache(512000)”
Locate the <VirtualHost _default_:443> tag and configure the following:
Add the following directive:
SSLProxyEngine On
Configure the path to your SSL Certificate saved in step 3-5 above:
SSLCertificateFile “C:\Program Files (x86)\Apache Software Foundation\Apache2.2\conf\extra\ssl\yourcert.pem”
Configure the path to your private key saved in step 3-5 above:
SSLCertificateKeyFile “C:\Program Files (x86)\Apache Software Foundation\Apache2.2\conf\extra\ssl\yourcert.key”
Optionally, configure the SSLCACertificateFile (you can download the appropriate bundle from your CA).
Optionally, configure logging directives.
Save and close httpd-ssl.conf
Restart the Apache2.2 service
Configure public DNS records and appropriate firewall rules to allow public http/https traffic to the external interface of your reverse proxy, and to allow the internal interface of
the reverse proxy to talk to the front end Lync server on 8080 and 4443.
From an external connection, test connectivity through the reverse proxy:
Test
https://dialin.company.com (friendly URL for getting dial-in information, if you’re using voice conferencing)
Test the Lync Web App by setting up an online meeting and following the URL to join the meeting. 
You can force the use of the web app by appending ?sl= to the end of the meet.company.com link. 
See this for more information http://blogs.technet.com/b/jenstr/archive/2010/11/30/launching-lync-web-app.aspx
Hope this information is helpful and saves some of you some money and trouble.
Please contact me if you need further clarification or see any mistakes in my notes.
Best regards,
Kenneth Walden
Enterprise Systems Supervisor
GSD&M
Austin, TX

Answer 1

I'd like to thank you for this article.  We were setting up Apache RP for Lync .... needless to say they weren't too excited to learn this new (and highly complex with lots of specific undocumented requirements) Microsoft product.  Anyways, your
blog saved me a LOT of headache.  I owe you big time. 
AWESOME JOB. 
-Greg
*****EDIT***
Decided to come back in there and post good information.  We had issues with EXTERNAL and ANONYMOUS users being able to attend a meeting.  The "DIALUP" url was working fine but the "MEETING" url was broken.  On our WFE servers we were getting
the event error as below.   Turns out that our reverse proxy was not set to "PROXYPRESERVEHOST ON".  Once we put that in there ALL was good.
Notice that the MEET portion was the only thing that was really broken.  So, if you can get DIALUP to work, but MEET doesn't ... your RP is working to FW the 443 to the 4443 correctly but you're RP is sending the wrong HEADER.  Look for
http://10.x.x.x/meet/ or soemthing in the event logs. 
Log Name:      Application
Source:        ASP.NET 2.0.50727.0
Date:          11/16/2011 1:26:35 PM
Event ID:      1309
Task Category: Web Event
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      OneofMyInternalWFEservers.local
Description:
Event code: 3005
Event message: An unhandled exception has occurred.
Event time: 11/16/2011 1:26:35 PM
Event time (UTC): 11/16/2011 6:26:35 PM
Event ID: b2039ecd0a62482284030f62e1e639d8
Event sequence: 129
Event occurrence: 28
Event detail code: 0
Application information:
    Application domain: /LM/W3SVC/34578/ROOT/meet-1-129658725547585993
    Trust level: Full
    Application Virtual Path: /meet
    Application Path: C:\Program Files\Microsoft Lync Server 2010\Web Components\Join Launcher\Ext\
    Machine name: MYWFE.local
Process information:
    Process ID: 14204
    Process name: w3wp.exe
    Account name: NT AUTHORITY\NETWORK SERVICE
Exception information:
    Exception type: HttpException
    Exception message: Server cannot append header after HTTP headers have been sent. 
Request information:
    Request URL:
https://FQDN:4443/meet/MyName/456456
    User host address: gatewayIP
    User: 
    Is authenticated: False
    Authentication Type: 
    Thread account name: NT AUTHORITY\NETWORK SERVICE
Thread information:
    Thread ID: 7
    Thread account name: NT AUTHORITY\NETWORK SERVICE
    Is impersonating: False
    Stack trace:    at System.Web.HttpHeaderCollection.SetHeader(String name, String value, Boolean replace)
   at Microsoft.Rtc.Internal.WebServicesAuthFramework.OCSAuthModule.EndRequest(Object source, EventArgs e)
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
Custom event details:
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="ASP.NET 2.0.50727.0" />
    <EventID Qualifiers="32768">1309</EventID>
    <Level>3</Level>
    <Task>3</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2011-11-16T18:26:35.000000000Z" />
    <EventRecordID>4483</EventRecordID>
    <Channel>Application</Channel>
    <Computer>XXXXXXXXXXXXXXXXXX</Computer>
    <Security />
  </System>
  <EventData>
    <Data>3005</Data>
    <Data>An unhandled exception has occurred.</Data>
    <Data>11/16/2011 1:26:35 PM</Data>
    <Data>11/16/2011 6:26:35 PM</Data>
    <Data>b2039ecd0a62482284030f62e1e639d8</Data>
    <Data>129</Data>
    <Data>28</Data>
    <Data>0</Data>
    <Data>/LM/W3SVC/34578/ROOT/meet-1-129658725547585993</Data>
    <Data>Full</Data>
    <Data>/meet</Data>
    <Data>C:\Program Files\Microsoft Lync Server 2010\Web Components\Join Launcher\Ext\</Data>
    <Data>SNKXS300</Data>
    <Data>
    </Data>
    <Data>14204</Data>
    <Data>w3wp.exe</Data>
    <Data>NT AUTHORITY\NETWORK SERVICE</Data>
    <Data>HttpException</Data>
    <Data>Server cannot append header after HTTP headers have been sent.</Data>
    <Data>XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX</Data>
    <Data>/XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX</Data>
    <Data>10.71.1.1</Data>
    <Data>
    </Data>
    <Data>False</Data>
    <Data>
    </Data>
    <Data>NT AUTHORITY\NETWORK SERVICE</Data>
    <Data>7</Data>
    <Data>NT AUTHORITY\NETWORK SERVICE</Data>
    <Data>False</Data>
    <Data>   at System.Web.HttpHeaderCollection.SetHeader(String name, String value, Boolean replace)
   at Microsoft.Rtc.Internal.WebServicesAuthFramework.OCSAuthModule.EndRequest(Object source, EventArgs e)
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean&amp; completedSynchronously)
</Data>
  </EventData>
</Event>