SOLUTION: White board and Poll don’t work between Lync 2013 clients

Problem:
White board and Poll don’t work between Lync 2013 clients.

Symptoms:
Desktop and application sharing between Lync 2013 clients work but White board or Poll don’t work with error network configuration problems etc…

During white board sharing if you run netstat on the client PC you will see the following:
netstat -ona | findstr 8057

TCP    10.XX.128.26:50656    10.YY.130.83:8057     SYN_SENT        4844
TCP    10.xx.128.26:50657    10.YY.130.83:8057     SYN_SENT        4844

here 10.XX.128.26 client trying yo connect to Lync 2013 FE server 10.YY.130.83 via port 8057. But the connection cannot be established and stays in SYN_SENT state for a while.
(4844 is the process id (PID) of lync.exe process)

Cause:
There is a firewall between client subnet and Lync 2013 FE server. And TCP port 8057 is not open from Lync 2013 Client PC to Lync 2013 Front End Server. White board and Poll require connection Lync 2013 FE server’s TCP port 8057.

Resolution:
Open the following port on the Firewall:

Source:
Lync 2013 Client subnet
Destination:
Lync 2013 FrontEnd Server
Port
TCP 8057

More Information:
in Ports and Protocols for Internal Servers documentation (http://technet.microsoft.com/en-us/library/gg398833.aspx) TCP 8057 is listed in “Required Server Ports (by Server Role)” section but not in “Required Client Ports section” Although it must be.

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4 Responses to SOLUTION: White board and Poll don’t work between Lync 2013 clients

  1. mehran says:

    Dear Friend
    We faced an strange problem after Lync 2013 fully implementation, would you give us any issue to solve this problems
    1- Whiteboard works about 30 minutes each time after Lync server restarting, for internal and external user both, and after that, it stops and give an error says “An error occurred while presenting”
    2- Totally we face “An error occurred while presenting” by PowerPoint sharing
    3- The call communication among two users that are both outside of domain is possible but the same call communication among a user inside domain and one outside of domain could be established , we added the user outside of domain the certificate and also in host etc, relevant IPs is added.
    We are in desperate need of a solution or guidance for this problem.

    Mehran

    • Refik Ünver says:

      Hello Mehran,
      1- As I understand the White Board works only 30 min after service resart and it stops. Since it works initially ports are open correctly on firewall, an no network routing issues. I faced with this kind of strange problems caused by antivirus softwares on the server. For instance Symantec AV Network Thread Protection module. Uninstall NTP if exists. You can install symantec AV without this module. Or other network level security product installed on the server? During the problem I recommmend to get network trace with wireshark and analyze. Also make sure that Lync FE server regional setting in English (for default user, and system default)

      2-For for power point presentation (On lync client you select power point icon) Office Web Apps server MUST be installed and defined in Lync topology. If everthing is correct about office web apps server I suspect network issues again like problem 1.

      3- I really don’t understand this problem. If you give more clear info I will try to help.

      hope this helps

      • Gabe Geise says:

        Are you saying that port 8057 needs to be open in both directions? I can telnet from my clients machine to the Front End servers over port 8057. However, I can’t telnet from the Front End servers to the machine hosting my Lync client over port 8057. I can share my desktop and applications but not whiteboard and poll. When running OCSlogger on the Front Ends I see that the request hits the Front Ends from the client but there is never a response back from the Front Ends to the client.

      • Refik Ünver says:

        Hello Gabe,
        You don’t need both directions. As in MS doc it says:
        “8057 Used to listen for Persistent Shared Object Model (PSOM) connections from client.”

        So client connects to port 8057 of the server. It is just TCP session , means client sets a random port on itself as source port and destination port is 8057. Most firewalls understand and keep the track of the tcp session and allows from server:8057 to client:random port. I hope your firewall does it.
        So you only need to open from client IP to server and destination port 8057.
        If I were you I took a wireshark trace on both server and client and see what happens. Since you can telnet 8057 from client, also make sure that FE server actually responds to telnet 8057 session. Not any other host in the middle like firewall. In some case telnet works but actually firewall itself accepts the connection like a proxy. For instance if you allow predefined protocols in Firewall instead of TCP port in the policy line, fw accepts connection not the server. I saw these cases on some firewalls. So test this:

        on client PC
        telnet feserverfqdn 8057
        run neststat -ona | findstr 8057
        you will see the 8057 connection to fe server and also Source random port. (lets say 50656 as in my post)

        on FE server:
        run netstat -ona | findstr clientip or netstat -ona | findstr 50656

        you should see the session with client IP and destination port 50656. If not client actually does not telnet to FE server. Some host in the middle accepts and responds to client.

        hope this helps.

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