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Skype for Business Blog
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SfB Server Now Supports Blocking NTLM Externally

Natasha Desai's avatar
Natasha Desai
Icon for Microsoft rankMicrosoft
Sep 25, 2018
I am happy to announce that with the CU7 version of SFB Server 2015, we have added the ability to block external NTLM traffic.  This, along with the use of Cert Based Authentication, will allow you t...
Updated Sep 25, 2018
Version 1.0
Modern authentication
Skype for Business
sengstar2005's avatar
sengstar2005
Copper Contributor
May 27, 2019

Hi Natasha,

 

I started going through the articles about enabling Modern Authentication. I got a few questions.

 

Currently without Modern Authentication :

 

1. Our domain-joined desktops uses Skype for Business clients. It connects to our on-prem Skype server, and this connects to our on-prem Exchange server for status availability i.e. in a meeting.

2. External users using mobile phones with Skype for Business clients connect externally (via NTLM). I can see on the mobile Skype client my Exchange appointments as well.

 

If I turn on Modern Authentication ONLY ON THE SKYPE Server :

 

1. Will my domain-joined desktops with Skype for Business clients still continue to use NTLM internally, or will they have to be re-configured to use Modern Authentication before they can connect to Skype server ?

2. If my domain-joined desktops with Skype clients change to use Modern Authentication, will that stop them seeing the Exchange calendar (because I didn't enable Modern Authentication on the Exchange server) ?

3. Will I also need to re-configure my mobile Skype client to use Modern Authentication or will the external NTLM authentication still work until I disable it  ?

4. If I re-configure my mobile Skype client to use Modern Authentication, will that stop it being able to see my Exchange calendar because I hadn't enable Modern Authentication on the on-prem Exchange server ?