### Understand the alert

This alert calculates the average number of TCP resets (`OutRsts`) sent by the host over the last minute. If you receive this alert, it means that your system is experiencing an unusually high rate of TCP resets, which might signal connection issues or potential attacks.

### What is a TCP reset?

A TCP reset (or RST packet) is a signal used in the Transmission Control Protocol (TCP) to abruptly close an active connection between two devices. It can be sent by either the client or server to inform the other party that they should consider the connection terminated.

### Why are high numbers of TCP resets a concern?

When there's a high rate of TCP resets sent by a host, it generally indicates problems in communication with other devices or services. This could be due to network latency, misconfigured firewalls, or aggressive timeouts causing connections to break. In some cases, it could also signal a potential Denial of Service (DoS) attack, where an attacker sends multiple resets to disrupt a service or network.

### Troubleshoot the alert

- Check the network performance

  Investigate if there are any network latency issues or congestion in your system. You can use tools like `ping`, `traceroute`, or `mtr` to check the network quality and connectivity to other hosts.

- Analyze packet captures for communication issues

  Use a packet capture tool like `tcpdump` or `Wireshark` to capture and analyze network traffic during the period of high resets. Look for patterns or specific connections that are frequently terminated with a reset. This could help pinpoint misconfigured services, firewalls, or devices causing the issue.

- Check firewall settings

  Ensure that your firewall settings are properly configured to allow necessary connections and not aggressively closing them. Look for rules related to connection timeouts, max connections, and SYN flood protection to see if they might be causing the resets.

- Review system logs for errors

  Check system and application logs for any error messages or events that correlate to the time of the alert. This might give you more information about the cause of the issue.

- Monitor for potential attacks

  If the above steps don't help determine the cause, consider monitoring your network and system for potential DoS attacks. Implement security measures such as rate-limiting and access control to protect your services and network from malicious traffic.

### Useful resources

1. [TCP Connection Resets and How to Troubleshoot Them](https://blog.wireshark.org/tcp/connection/resets/troubleshoot/)
