Citrix: XenDesktop 5 Logon Process and Communication Flow

Martijn Bosschaart just posted CTX128909 on twitter, this article contains the following information on XenDesktop 5 Logon Process and Communication Flow:



  • The user device submits credentials to the Web Interface site.
  • Web Interface passes the user credentials to the controller.
  • Controller verifies user authorization by performing a Microsoft Active Directory query with the end user’s credentials.
  • Controller queries the site database for the end user’s assigned desktop groups, named instance uses ports 1434 and 1433.
  • Using the desktop group obtained from the database, controller queries the hypervisor about the status of desktops within that group.
  • Controller identifies to Web Interface the desktop it assigned for this particular session.
  • Web Interface sends an ICA file to the online plug-in, which points to the virtual desktop identified by the hypervisor.
  • Online plug-in establishes an ICA connection to the specific virtual desktop that was allocated by the controller for this session.
  • Virtual Desktop Agent verifies the license file with the controller.
  • Controller queries Citrix license server to verify that the end user has a valid ticket.
  • Controller passes session policies to the Virtual Desktop Agent (VDA), which then applies those policies to the virtual desktop.
  • Online plug-in displays the virtual desktop to the end user.
  • Administrator and helpdesk personnel use Desktop Director and Studio tools to manage the desktops from the management server.

Note: Source port will be random open port. This is for reference only and should not be used for security and/or architecture review.

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Kees Baggerman

Kees Baggerman is a Staff Solutions Architect for End User Computing at Nutanix. Kees has driven numerous Microsoft and Citrix, and RES infrastructures functional/technical designs, migrations, implementations engagements over the years.


  1. Paul Bergetz says:

    Very nicely done. Easy to read and understand. I have been using and setting up virtual systems since the first Citrix and MS Terminal servers and am amazed at all the mis-information out there. Hopefully you will continue and keep up with storing or linking well done information that is available. I just spent half a day researching licensing issues with xd5 only to find that there is a xd5 express and the technical rep I spoke with (when I installed 3 weeks ago) led me to the evaluation version which uses different licensing as a result my systems are timing out ( and I will need to re-install xd5 express version.

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