Lync Reverse Proxy using Apache - External Users can't get to Web Client

Posted on 2011-10-27
Last Modified: 2012-05-12
I have Lync 2010 installed and working for the most part. FrontEnd, Edge and Reverse Proxy.
I used the following procedure to configure the Apache Reverse Proxy.

This allows External users to connect to a meeting using a installed Lync client.  External Users can also get to  

External Users can't get to a meeting link like this example:, they get a "cannot display the web page" error.

Internal users work OK. Internally if I use it works OK.  Users can also use https://meet.domain.com4443/name/ABCDEF?su= and see the Lync client options page internally but not externally.

This appears to be something with the Apache Reverse Proxy.  Can it be configured to work with Lync to support full access?  If so, how?  Can I use another Reverse Proxy (free)?  If so, how to configure?  We don't have Forefront and I don't really want to have to buy it just for this purpose but may have to it's the only solution.

Question by:DigitalInfuzion
    LVL 26

    Expert Comment


    From the Apache server, can you open a browser Window (may need to remote desktop to it) and connect to the internal Lync 2010 server? As we need to rule out a firewall / rooting issue.

    If the Apache server connectivity test works, next question is what HTTP error code are you external user seeing, two ways,: first in you Browser of choice: IE, Firecox, Chrome, hit F12, and select the Net tab. If using IE, click the "Start Capturing" button, then surf to

    See what code is returned.

    Alternatively, or in parallel have a look at the Apache Access and Error logs.
    LVL 1

    Author Comment

    From the Apache server I get the same symptoms as from outside.  I can get to but not to

    Using FireFox externally on the errored URL I get an error that FireFox can't find the server at  The reverse proxy points to the internal server.


    It appears as if when going to the errored URL that a java script could be pointing to an internal resource thus causing the problem???  I don't know how/what Lync does to connect at this level.

    LVL 26

    Expert Comment


    I suspect there is something up with your httpd.conf, as you shouldn't see anything in the Apache Access logs, for requests that have been proxied to Lync.
    LVL 1

    Accepted Solution

    Thanks for the assistance it turns out my problem was with Lync.

    Lync uses various URLs to point to different services (even if it's the same ip address). is one but it also needs (or whatever you want to call it).  On the Lync Front End server you need to configure an internal and external URL.  The external URL ( was not externally resolvable.  I updated the external URL ( in the Lync Topology Builder, published it and created an external DNS entry for it.  Once it propagated everything works.
    LVL 1

    Author Closing Comment

    It was not an Apache or Reverse Proxy problem but a Lync configuration problem.

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