How it works on the wire: IIS HTTP Client certificate authentication

I collaborated with a colleague recently where the IE client was failing to authenticate to IIS and I was requested to analyze a few network traces collected while reproducing the issue. The main issue was that the client (IE) wasn’t able to successfully authenticate to IIS server when certificate authentication was configured on IIS side and was getting the…


DNS SRV lookup from Powershell

[After posting this blog, I have realized that Powershell 3.0 already provides a built-in cmdlet called Resolve-DnsName which could help you make any kind of DNS queries. But I still wanted to leave this blog post active for those who might want to see how it could be done with Win32 API. Also Powershell 3.0 is…


Testing STUN/TURN server connectivity from external networks through UDP 3478 by using Powershell

Hi there,   While working on a Lync connectivity test tool, I developed a STUN/TURN server connectivity test script in powershell which might be handy when you want to make sure that your external clients will be able to communicate with STUN/TURN server via UDP 3478 (STUN/TURN connectivity through TCP will also be added later on)….


External Lync 2013 clients cannot upload ppt or other files and whiteboard, poll, Q&A are greyed out on Lync client

Hi again,   In this blog post, I want to talk about a Lync 2013 problem where external users fail to upload powerpoint presentations. When external Lync user tries to upload a ppt file to an online meeting, basically nothing happens and once the failure occurs, all web conferencing related features are greyed out on…


Decrypting SSL/TLS sessions with Wireshark – Reloaded

Hi there,   In a previous blog post of mine, I went through the steps of decrypting SSL/TLS traffic by using wireshark and openssl tools. In this blog post, I wanted to talk about the same procedure again because it got even easier to decrypt encrypted traffic with Wireshark since then.  Here are the steps…


Running Lync 2013 WebApp plugin in locked down Terminal server environments

Hi there,   In this blog post, I would like to talk about running Lync 2013 Webapp in Windows Terminal server environments. Lync 2013 Webapp feature has a client side plug-in which provides audio/video/application sharing functionality and this plug is installed per user, in other words installation program installs files and creates registry settings in…


Event ID 56417 may be logged on Lync server 2013 intermittently

Hi again,   I dealt with a Lync server 2013 problem recently where the server was intermittently logging event ID 56417 in the Lync server event log:   – <System>   <Provider Name=”LS Data Collection” />   <EventID Qualifiers=”51423″>56417</EventID>   <Level>2</Level>   <Task>2271</Task>   <Keywords>0x80000000000000</Keywords>   <TimeCreated SystemTime=”2013-05-10T12:16:51.000000000Z” />   <EventRecordID>18850</EventRecordID>   <Channel>Lync Server</Channel>   <Computer>FE1.contoso.local</Computer>   <Security />   </System> – <EventData>   <Data>QoE…


Lync 2013 client may crash when Organization tab is clicked

Hi there,   I was dealing with a Lync 2013 client crash problem a few months ago and I wanted to provide some details on this issue since you might hit the same problem in your deployments as well when certain conditions are met. The exact problem was that when a user clicks on the…


Cumulative update version information for Lync client and Lync server

[Last updated on 27th February, 2014]   Hi there,   You can find a list of CU versions compiled from KB articles for cumulative update packages released for Lync client and Lync servers. Please note that the list only includes version information for Lync 2010 (desktop edition), Lync Server 2010, Lync 2013 (desktop edition) and Lync…


Exchange integration error on HP4120 desktop phones – A CA trust issue

I would like to go through an integration problem between Lync phone edition devices and Exchange 2010 that I worked on a while ago. Since the integration wasn’t working properly, users couldn’t access call logs, recorded voice mails, calendar information etc from their desktop phones (HP4120).   To understand the problem in more details, we…