I’ve run into a few issues lately where customers are currently using ThinOS 8.x successfully with Citrix Netscaler/ADC but having issues connecting with Dell Wyse ThinOS 9.x.

In more than one case, it’s been an issue with the existing Netscaler Session Policy that was setup specifically for Wyse devices and contains information from the ThinOS 8.x User-Agent HTTTP/S request header that may no longer apply to ThinOS 9.

The ThinOS 8.x User-Agent request header is: CitrixReciever WTOS/1.0

The ThinOS 9.0 User-Agent request header is: “CitrixReceiver”/18.12.0.65534 (X11; Linux x86_64) Warthog/9.0.8024 (Release) X1Class CWACapable

**Update 8/2021 #1 ** ThinOS 9.1 User-Agent request header has been changed to: CitrixReceiver/18.12.0.65534 (X11; Linux x86_64) WTOS/9 (Release) X1Class CWACapable (‘Warthog/9.0.8024′ was replaced with: ‘WTOS/9’)

**Update 8/2021 #2 ** If ThinOS is using the built-in web browser to connect to an MFA site, for example, Okta, Duo, etc.. then the HTTP header will be one of the following:

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Warthog/9.0 Safari/537

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.181 Electron/3.1.11 Safari/537.36

Note: The following below may not be true if using >9.1 as the http header now again contains “WTOS”.

The issue I’ve seen is many customers using ThinOS 8.x have a Netscaler Session Policies setup to look for a User-Agent to include “WTOS” or “WTOS/1.0” and that does NOT exist in the 9.x User-Agent header so the existing Session Policy will be ignored and not applied.

Network trace from ThinOS 8.6_511:

Network trace from ThinOS 9.0_4024:

 

Network trace from ThinOS 9.1.2101 / CWA 21.1.0.14.8

 

To fix this, you have 2 options.

Option #1: Create a new session policy on Netscaler/ADC to contain something from the ThinOS 9.x header, for example, ‘Warthog’ (name for ThinOS 9) so it uses the policy.

Option #2: Wyse Management Suite has the ability to specify the User-Agent header under the WMS Citrix Broker/Netscaler section.  

• Under ‘Citrix Broker’ settings from ThinOS 8.x policy

• Under ‘Broker Settings’ settings from ThinOS 9.x policy

Finally, we also saw an issue where we get the following error; INFO: “Waiting for token to change, then enter the new tokencode”

The existing Netscaler/ADC policy was set to have an RSA policy first BUT since that policy was setup using the 8.6, “WTOS”, header, it was going to the second policy and only allowing LDAP, but threw this error. Once we fixed the policy as noted above with proper header, we were able to use or RSA policy as primary, and the LDAP as secondary.

You can configure this behavior under the “Citrix Netscaler/ADC” settings section in the ThinOS 9 policy.  

Hope you found this helpful!

@chris_messier ~~> Subscribe to blog to get latest updates <~~