SFB Mac Flow Vs. SFB Windows Flow ?

[Vincent Goubert]

Hello Guys,

I am working as network engineer and trying to implement Zscaler through one of my customers infrastructure.

We are encountering an issue with this Cloud Proxy and the usage of Skype for Business on Mac OS :

It seems that Skype on Mac is not using the same flows to send data to Microsoft than on Windows OS.

By taking a look at the flow output (WireShark), here is the differences : 

- Windows : SFB is using the PAC file settings, sending the data to the Proxy server if UDP fails.

- Mac : SFV is ignoring the PAC file configuration, trying to send in any ways the data to Microsoft's servers using STUN protocol.

The customer configuration is made in the way that only Zscaler flows are allowed to go out of the network, as Windows is using TCP 80/443, it works perfectly, but with Mac OS, everything works except the conference mode.

This mode is ignonring system proxy and always tries to join Microsoft's server directly.

Did anyone knows how to bypass this issue, or to force SFB on Mac OS to use TCP 80/443 ?

Thanks in advance,

Regards,

Vincent.

[#2]

@Vincent Goubert I suspect this to always be the case, we tried to get Skype on a mac to respect proxy settings for some time and didn't get it to work. We also failed to get Creative Suite, Citrix and other apps to respect proxy settings. We made some progress with unauthenticated proxies, but not to a point we would declare reliable.

OSX doesn't really have a concept of a system proxy, it's more that Safari has a proxy, chrome has a proxy etc.

Irrespective, Skype and Teams really dont give you the best experience when running through a proxy, true UDP is by far the fastest way to shift real-time audio and video data. Wrapping this in HTTPS and bouncing through proxies is never very good. See Microsoft's guidance here

https://docs.microsoft.com/en-gb/SkypeForBusiness/optimizing-your-network/proxy-servers-for-skype-fo...