topic Re: Lync (Skype for Business) Across Organisations in General Topics

Lync (Skype for Business) Across Organisations

Jack_Howells — Mon, 08 Aug 2016 08:22:37 GMT

Hi guys,

Is anyone else having issues using Lync (Skype for Business) when messaging, or sending file transfers, to someone in a separate Skype Organisation in an external network?

Not sure if this is a bug or not, as the application is being seen as Incomplete, and looking at Packet Captures the SYN ACK isn't being received.

Kind regards

Jack

Re: Lync (Skype for Business) Across Organisations

_slv_ — Mon, 15 Aug 2016 13:15:41 GMT

Hello

I'm using Skype for Business almost every day and I dont see any issues.

If You want please send me PM with Your skype login so I can send a message to You.

Regards

SLawek

Re: Lync (Skype for Business) Across Organisations

Shannon-Rowe — Thu, 18 Aug 2016 22:12:13 GMT

Are you hosting your own SfB infrastructure, or cloud-based? Do you run decryption? Have some experience under these scenarios which doesn't work well through PAN, if this is applicable let me know and I will provide more detail.

Cheers,

Shannon

Re: Lync (Skype for Business) Across Organisations

Jack_Howells — Sun, 21 Aug 2016 09:22:47 GMT

Hi Shannon-Rowe,

It's on-premise so yes their own SFB infrastructure. Disabling decryption meant we could send files through 5 attempts but after that it failed. Looking into the PCAPs and flow basic shows that two internal IP addresses are trying to talk to one another. This is something to do with STUN right? Instead of STUN it's trying to use ports 50,000-59,000.

Cheers

Jack

Re: Lync (Skype for Business) Across Organisations

Shannon-Rowe — Tue, 23 Aug 2016 19:33:19 GMT

Hi Jack,

Yes that is just a behaviour of STUN, it is a bit confusing when you see that in the packet capture.

Cheers,

Shannon

Re: Lync (Skype for Business) Across Organisations

Jack_Howells — Wed, 24 Aug 2016 08:08:59 GMT

Hi Shannon,

Indeed, but it's not going through a port that STUN uses. STUN doesn't use any ports between 50,000-59,999 which is why it won't work I believe. Internal IPs can communicate over STUN for Lync file transfers but not anything else.

Cheers

Jack