Citrix Netscaler supported for Lync 2013


Microsoft just updated its support matrix for Lync 2013 (Finally) Where Netscaler is listed as supported for Reverse Proxy and for Load balancing –>

You can also read the deployment guide for Netscaler and Lync here –>

Citrix Netscaler and SSL3 “poodle” exploit

Earlier today, Google published a article regaring how hackers can exploit a vulnerability in the SSL 3.0 protocol. Which you can read more about here –>

You can also read more about the specific attack in detail here –>

Microsoft recommends that you disable SSL 3.0 using Group Policy on Windows Computer, since it is by default enabled, you can read more about it here –>

UPDATE::: Citrix has added a article on this exploit as well –>


Citrix Netscaler we can be fore flexible. For Netscaler Gateway we can define which type of SSL profiles or protocols which are going to be enabled for the session. We can create a new front-end SSL profile which we can attach to the Netscaler Gateway. Front end policies are used when a client is connecting to a vServer


Here I define that TLSv1 is enabled, and that the client cannot use SSLv3. (This is a screenshot from a VPX) and therefore TLSv1.1 and 1.2 cannot be enabled for this profile, and by default Citrix Receiver only supports TLS1 not the newer versions.

After I created the protocol I can bind it to a Gateway vServer


Now If I have other load balanced vServer I can also disable SSL for these vServers, but it is important to check if the clients that are connecting actually support TLS.

NOTE: I have not verified that this works for most browsers but I verified that my client can connect to the gateway vServer using TLS and not SSL3.

Netscaler masterclass presentation Oktober 2014

Today I presented on the Netscaler masterclass on the subject,  System Center and Netscaler and here is my presentation –>

My talk consisted about using the different integrations between System Center and Netscaler, primarly on

* Virtual Machine Manager and Netscaler (Using the load balancer extention to deploy load balancing rules for service templates)
* Operations Manager and Netscaler (How to setup monitoring for Netscaler and use it together with Distributed Applications)
* Orchestrator and Netscaler (How to setup automation tasks against Netsacler using the NITRO SDK)

And as promised in the presentation here is my scripts that I use for the different tasks.


Add-Server activity (Note that this requires that the SDK is added to C:\SDK folder and that the different DLL files are added to the global assembly cache.

Set-location «c:\sdk»
[System.Reflection.Assembly]::Load(«System.EnterpriseServices, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a»)
$publish = New-Object System.EnterpriseServices.Internal.Publish

(ADD THE DLL files to the global assembly for Orcehstrator to use for reference)



$path1 = Resolve-Path «C:\sdk\lib\Newtonsoft.Json.dll»
$path = Resolve-Path «C:\sdk\lib\nitro.dll»

$user = «»
$pass = «»
$nsip = «»


$nitrosession = new-object com.citrix.netscaler.nitro.service.nitro_service($nsip,”http”)
$session = $nitrosession.login($user,$pass)

$server1 = New-Object com.citrix.netscaler.nitro.resource.config.basic.server
$ = «»
$server1.ipaddress = «»


$service1 = New-Object com.citrix.netscaler.nitro.resource.config.basic.service
$ = «»
$service1.servicetype = «»
$service1.monitor_name_svc = «»
$service1.port= «»
$service1.servername= «»

Create Load balanced Service

$nitrosession = new-object com.citrix.netscaler.nitro.service.nitro_service($nsip,”http”)
$session = $nitrosession.login($user,$pass)

$lbvserver1 = New-Object

$lb_to_service = New-object
$ = «»
$lb_to_service.servicename = «»

Using Netscaler Application firewall to protect against ShellShock

With the recent announcement of the ShellShock vulnerability many vendors have done a great job with coming with patching / fixes to close the vulnerability. Citrix has released an knowledge article which shows what Citrix products are affected here –>

But! Citrix has also released an update to AppFirewall signature to include fixes to services which are exposed via Netscaler. For instance if we have an load balanced service which is load balanced via Netscaler, and the services running in the back are affected or vulnerable we can use AppFirewall to protect them from the attack.

First we need to update the signature files (Citrix released an update yesterday) (Update version)

Then we can see that the new signature files include fixes for shellshock.


The actions are by default set to block. So when creating an appfirewall policy we can bind this to an particular vServer or URL.


Important to set signature action to block



But note that these rules only apply to services that are exposed via the Netscaler, and not the netscaler itself. Refer to the document which is posted above.

Using Netscaler with UPN and Storefront

Had a case earlier today where a customer wanted to configure Netscaler to authenticate with UPN instead of SamAccountName. And using UPN instead of SamAccountName makes sense in many cases, since it easier for users to remember their email-address instead of their username.  So in this scenario my samAccoutName is msandbu and my UPN is

Now by default Netscaler is setup with samAccoutName under server logon name attribute. This defines what kind of account name you are allowed to logon with using Netscaler.

If you try to logon with UPN when SamAccountName is defined you will get this kind of error message on the StoreFront Server.


So Storefront strips the domain info sent from the Netscaler and tries to validate the credentials to Active Directory.

So how to fix this ?

You have to define the SSO name attribute in the LDAP credential, to samAccountName.


Then the Netscaler firstly validates the UPN, get the SamAccountName of the user and then forwards that to Storefront and logs in.

Important to remember that Storefront always tried to revalidate the info from Netscaler


Presenting on Netscaler Masterclass

On the next Netscaler Masteclass in October I will be presenting a session, regarding System Center and Netscaler. To talk about different forms of integration and monitoring.

For those who aren’t familiar with the Masterclass it is a webinar series that is hosted by Citrix, which are hosted once a month.

So sign up here if you want to know more –>

Netscaler 10.5 review

Now since the release of 10.5 I have been able to test alot of the new features in the latest release. Citrix has also released new versions of Insight and Endpoint clients for Windows & Mac to match the new release.

The upgrades have so far for my part have been non-problematic (in case of a custom GUI you may need to recreate it) from 9.3 and even 10.1 builds. For those that are in a migration plan please refer to the migration document from Citrix

I have also seen a performance increase in some scenarioes.

There has also been an update on the clustering features, which didn’t caught my eye at first. Which allows us to have a Netscaler Gateway vServer running on a local Netscaler node.

Now the new build is 99% pure HTML which is great! there are still some features which still requires JRE, but this is going to be fixed in a future release.

The following features or nodes still require JRE:

  • System
    • Upgrade Wizard
    • Diagnostics
    • User Administration
      • Command Policies
      • Command Policy RegEx Editor
  • Visualizers
    • Network > Network Visualizer
    • Network > TCP/IP connections
    • Traffic Management > Load Balancing > Visualizer
    • Traffic Management > Content Switching > Visualizer
    • Traffic Management > GSLB > Visualizer
  • Security
    • Application Firewall
      • Application Firewall wizard
      • Add/ Edit/ Import profiles
      • Signatures
        • Add
        • Update Version
        • Auto Update Settings

Citrix has also made easier integrations for their own products such as XenDesktop/XenMobile/Sharefile and so on, which makes it easier for consultants to deploy Netscaler solution to provide availability for other products.

Now all of the new features are listed here –>

One thing which I find is the most important featue in the latest build (besides the new GUI) is the front-end optimization feature which allows the Netscaler to reduce load and render times on web pages which are rendered on a client browser, after some intials tests with this feature I was able to save 60% of the load time. Since in most cases a web site is not optimized for speed, and therefore Netscaler might be an important piece there.

But to sum it up so far, I’m really impressed with the latest release and how Citrix has made Netscaler even more powerful with more then 100 more features, and makes it a more key component in most datacenters. Looking forward to the later releases to see what Citrix has up their sleeve! Smilefjes som blunker

Netscaler Insight with Appflow and Session reliability

A couple of days ago I was involved in a case where ICA sessions were suddenly disconnected and the users were unable to reconnect. The setup was a simple ICA-proxy access gateway using the latest build (126) and there were no error messages on the Storefront server.

After involving Citrix support they recommended that we disable AppFlow for the access gateway (since this deployment used Netscaler Insight to monitor ICA sessions) then suddenly things started to work again.

Now I knew that I’ve seen this issue before somewhere on twitter, a quick tweet discovered that someone else has seen the issue as well.


So apparently using Appflow with session reliability is a NO-GO!

If someone has managed to test this with 10.5 please give me some feedback if this has been fixed!

Netscaler 10.5 what’s in it

So there has been some fuzz regarding the latest release of Netscaler 10.5 (also codename Tagma) which should been the death of Java GUI within Netscaler. Not quite there yet..

So what has Citrix improved / added in this feature ? Well it is quite a lot. Citrix states that they have added over 100 new features in this release. Beta 1 has just been released to partners, and beta 2 is on its way which is coming mid may.

In the later betaes which are coming there are coming more templates to App and load balancing. But let us focus on the news that’s arrived now.

  • HTML5 based GUI
  • NITRO SDK for Python
  • NITRO for File Operations
  • NITRO for ZebOS system
  • GSLB Static proximity sync
  • SSL configuration Profiles
  • CNAME record caching
  • Multiple Port CS
  • AAA Session Stickiness
  • Kerberos Performance
  • Jumbo Frames
  • Link Redundancy
  • SPDYv3 Gateway
  • SDX Manageability
  • Front End Optimization
  • Insight Center Enhancements

First of is the GUI which is now mostly pure HTML 5 which makes it quite snappy! I would say that about 80% of the GUI is now HTML 5, some features such as running trace still uses Java (Im guessing this is something that is going to get fixed in a later release.


So what is new under licensing part ? We can see that there are some new features which appear here, such as Integrated Disk caching and RISE (Which is part of the Cisco platform)


There is also two new “features” within Traffic optimization


* Front End Optimization (Which converts data which is being sent back to the user, such as convert image files)


And we have content accelerator (Which is used for integration with Citrix ByteMobile)

Also setting up a new Netscaler Gateway is also alot easier since we don’t need the Java part anymore.


Also support for LLDP is here, which is a information exchange protocol kinda like CDP (from Cisco) So here is a comparison between the old GUI and the new GUI


There is also a list of new monitors which are built-in


Also support for LACP on interfaces which allows you to team NICs.



Citrix has also added some basic wizards which allow for easier setup against XenDesktop / Sharefile and such.


Also SSL profiles and DTLS profiles


We also have support for Jumbo Frames which allows for up to 9000 bytes of payload instead of 1500.

And one thing that is missing is Edgesight monitoring from Netscaler which looks like it has been removed for good. One thing which I didn’t find in the beta but is mentioned in the video is support for Oracle (which most likely coming in a later beta) o this is just my findings in the latest Beta. ill update when the next beta is coming! Looks like we have much to look forward to! Smilefjes

Netscaler VPX and Vmware latency issue

In the many releases of Netscaler VPX (Starting with builds after 9.2) have had some minor issues with additional latency when running on VMware.

This has been a known issue for quite some time, and of course there has been a workaround available as well.

NetScaler VPX Appliance

  • Issue ID 0326388: In sparse traffic conditions on a NetScaler VPX virtual appliance installed on VMware ESX, some latency might be observed in releases after 9.3 as compared to release 9.2. If this latency is not acceptable, you can change a setting on the appliance. At the shell prompt, type:
    sysctl netscaler.ns_vpx_halt_method=2

    Perform a warm reboot for the above change to take effect. To have the new setting automatically applied every time the virtual appliance starts, add the following command to the /nsconfig/ file:

    sysctl netscaler.ns_vpx_halt_method=2

But! I am happy to say that this has been fixed in the latest build (126.12) so we no longer require to run the commandline to fix the latency issue


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