What triggers the sending of a TCP/IP reset (RST) flag?

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A TCP/IP reset (RST) flag is sent when a device wants to immediately terminate a connection. This can happen when:

1. The receiving device detects an error in the data received and wants to signal the sender to stop sending data.

2. The receiving device receives data that is not expected or out of order and wants to reset the connection to start over.

3. The sending device has been idle for too long and the receiving device sends a RST flag to close the connection.

4. A security device such as a firewall or intrusion detection system detects malicious traffic and sends a RST flag to terminate the connection.