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Archive for the ‘XenApp’ Category

Citrix Techedge Videos

January 14th, 2013 No comments

Here are some of Techedge (EMEA) Videos worth watching with some good content and great presentations: -

Citrix TechEdge is a free event hosted by top Citrix Technical Support engineers at Citrix Summit and Synergy, where you gain in-depth knowledge on the latest troubleshooting tools, methodologies and fixes for your Citrix Application Delivery Infrastructure. (Ref: http://support.citrix.com)

TechEdge 2010 Presentations and Videos – http://support.citrix.com/article/CTX127035

TechEdge 2011 Presentations and Videos – http://support.citrix.com/article/CTX131342

TechEdge 2012 Presentations and Videos – http://support.citrix.com/article/CTX135521

 

Lesson Learned – Orphan process

February 17th, 2012 3 comments

writing something after almost two months…not good but I was busy in lots of stuff, trying to learn new things which I will document later… But for today something on Analyzing dump for hangs due to orphan processes.

Recently while working on one issue, I found an interesting case scenario… this seems to be one common scenario… when users logoff from their session on TS\XenApp server, three processes stuck there – Csrss, Winlogon and LogonUI. Though they logged off but because of these processes, there session stuck, eating resources and some stage give unexpected behaviour…It is bit difficult to show the full stack here but I am documenting the technique that I used to find the root cause of the issue. So here’s what I did.

Complete Memory Dump – for hang related issue, it is good to take complete memory dump and atleast 2-3 to see the consistency (this what I usually do)…

Step 1 – Ensure symbols are loaded, may be a good idea to run lm command and too see what files are loaded and then run .reload /f to force the symbol download.

Step 2 – Find out all the processes, it will be good to have them in sort order by session so I ran command !sprocess -4 . this show me all the sessionss in proper order and also, what all processes are available in each session. Read more…

Debugging for Starters – III

December 13th, 2011 1 comment

Debugging for Starters – III

First two blog posts in this series are -> http://blog.lkctx.com/debugging-for-starters-i

http://blog.lkctx.com/debugging-for-starters-ii/

We already discussed different terminologies, different types of dumps, tools to create dumps and also, how to check if they are good for analysis or not. In next couple of articles, I will document steps require to open a dump in Windbg. I will also try to document  steps require to troubleshoot some common issues related to :-

  1. Application\Server crash
  2. Application\Server hangs
  3. CPU Spikes, etc;

and will add some more tools as and when require.The main tool that we are going to use is Windbg.

http://www.microsoft.com/whdc/devtools/debugging/debugstart.mspx

The installation of Windbg is pretty simple, anyone who has ever installed any software on Windows , can do it. However, before opening the dump, you need to configure the symbol server.

Symbols – In simplest way, Symbols (.pdb files, generated during application compilations) convert 01010101 to ‘human readable’ English. There are more technical definitions exist on internet but this is the simplest I can think of. Symbols are provided by the application vendors, usually they have their Public facing Symbols server. For example: -

Read more…

SmartCard APIs

December 11th, 2011 No comments

SmartCard APIs call sequence – SCardEstablishContext, SCardConnect, SCardTransmit, etc

Some days ago, I was working on one very interesting case related to Smartcard behaviour on XenApp. While I can’t disclosed all the findings but still would like to share some of the learnings. It is very important to understand the behaviour of SmartCard APIs, how they work, etc. (check MSDN). MS has released documentations related to different protocols, one that interest me a lot (as I work on mainly Smart card, Authentication, etc issues) is related to ‘Remote Desktop Protocol: Smart Card Virtual Channel Extension’.

Ref: – http://msdn.microsoft.com/en-us/library/cc242596(v=PROT.10).aspx

This example shows the messages sent to perform a simple querying of a card in the TS client machine. It assumes that a channel has already been set up on the between the TS client and the TS server. In addition, a PC/SC-compatible resource manager is running on the TS client and there exists a smart card reader with a smart card inserted. The following figure represents the program flow. Read more…

XenApp Single Sign-on using Smartcard for non-Domain joined machines (NDJ)

November 20th, 2011 2 comments

XenApp Single Sign-on using Smartcard for non-Domain joined machines (NDJ)

My original post is here http://blogs.citrix.com/2011/11/09/smart-card-single-sign-on-using-kerberos-constrained-delegation-for-ndj-clients/

While working on issues related to Smartcard authentication, one common query we receive in Tech-support is – how can we make Single Sign-on working with Smartcard for Windows 7Vista clients? With ‘Full Kerberos’ support this works for Domain-joined clients. I was recently working in my lab to simulate the behaviour and to use ‘Constrained Kerberos Delegation’ to configure Passthough behaviour for non-domain joined machines using authentication point as ‘At Web Server’.

Read more…