Why im seeing (FIN,ACK) as a respond from microsoft teams hosting IP.?

Hello Test HIK A3**,**

Good day!! Thank you for reaching out to Microsoft community.

"Seeing (FIN, ACK) packets in Wireshark is a normal part of TCP connection management and indicates that a connection is being closed gracefully". It is not necessarily an error message.

The HIK ClassIn module initiates the RTMP streaming connection to the Microsoft Teams hosting IP.

During the streaming process, the connection is terminated, either by your device or the Microsoft Teams server.

The termination of the connection is signaled by the sending of a FIN packet, and the receiving end acknowledges it with an ACK packet.

The presence of the (FIN, ACK) packets in your Wireshark capture indicates that the connection is being closed normally, as part of the TCP connection lifecycle. This is a common and expected behavior when a connection is terminated, and it does not necessarily indicate an error or problem with the RTMP streaming.

The error message you're seeing, "disconnect from server," may be related to other factors, such as network issues, server-side configuration, or compatibility between the HIK ClassIn module and the Microsoft Teams platform. The source IP which Acknowledged this disconnection was one of the data centers of Microsoft.

Here's a more detailed explanation regarding the Understanding of TCP Connection Closure:

• FIN (Finish): The FIN packet is sent by one side of the connection to indicate that it has no more data to send. This signals the other side that the connection should be terminated.
• ACK (Acknowledgment): The ACK packet is sent in response to the FIN packet to acknowledge the receipt of the disconnect request and that the connection can be closed.

It should only end of the connection (in this case, the Microsoft Teams hosting IP) sends a FIN packet to indicate it has finished sending data.

On the other hand, at the receiving end (your device) responds with an ACK packet to acknowledge the receipt of the FIN.

1. Second FIN: The receiving end then sends its own FIN packet when it has finished its data transmission.
2. Final ACK: The original sender (Microsoft Teams hosting IP) acknowledges this FIN with an ACK.

Relating to Your RTMP (Real-Time Messaging Protocol) Streaming Issue:

If you encounter a FIN, ACK packet and a disconnection message when trying to stream using the HIK ClassIn module, it could indicate a few potential issues:

Server-Side Closure: The server (Microsoft Teams or another intermediary) is closing the connection, possibly because:

• It doesn't support or allow RTMP streaming from your source.
• There's a misconfiguration or incompatibility.
• There are network policies or security measures that terminate the connection.

Troubleshooting Steps:

Ensure that your RTMP streaming settings are correctly configured in the HIK ClassIn module. Verify the stream URL, port, and any required authentication.

Compatibility: Verify that Microsoft Teams (or the intended destination) supports RTMP streaming from your device and source. Some platforms may have restrictions or require specific configurations**.** Hardware requirements for Microsoft Teams - Microsoft Teams | Microsoft Learn.

• list of unsupported decoders and encoders: Hardware decoder and encoder driver recommendations - Microsoft Teams | Microsoft Learn.
• For Teams live events the list of unsupported decoders and encoders: Hardware decoder and encoder driver recommendations - Microsoft Teams | Microsoft Learn.

Firewall or Security Software: Security measures (firewalls, antivirus, etc.) on your network or the server's network could be terminating the connection.

• Check if there are any network policies or firewall rules that might be blocking RTMP traffic.
• Importantly, please whitelist only listed IP's from your device firewall or software and then ask to stream again.
• Follow this article for Teams server IP's: Microsoft 365 URLs and IP address ranges - Microsoft 365 Enterprise | Microsoft Learn.
• 
• Also check below MS Doc: Teams settings and policies reference - Microsoft Teams | Microsoft Learn & Teams settings and policies reference - Microsoft Teams | Microsoft Learn.

I hope these steps help resolve the issue you're experiencing with the new Teams app.

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We look forward to hearing back and having a great day ahead!

Sincerely

S M Nazmun Nur | Microsoft Community Moderator