System Behavioural Checks
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System checks are designed to spot ntopng problems and thus make sure the application is healthy.

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**Intrusion Detection and Prevention Log**
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Checks for Intrusion Detection and Prevention logs.

Ntopng notifies when a host has been added or removed from the jailed hosts pool.

The Alert is sent when unusual logged events are detected.

*Category: Internals*

*Not Enabled by Default*


**Periodic Activity Not Executed**
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Checks for periodic activity execution.

The system sends an alert when a periodic activity is queuing and is not getting executed.

The alert is sent when the worker threads are busy.

*Category: Internals*

*Enabled by Default*


**Slow Periodic Activity**
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Checks for slow periodic activity.

A periodic activity is taking time to start the execution.

The alert is sent to notify that a periodic activity takes too long.

*Category: Internals*

*Enabled by Default*


**System Alerts Drops**
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Checks for a system alerts drops.

Too many alerts are generated in a short period of time, this may cause the system dropping the alerts.

The alert is sent when there is no room in the internal alerts queue and the alerts are dropped.

*Category: Internals*

*Enabled by Default*


**Vulnerability Scan Changes**
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Checks for Vulnerability scans.

Ntopng notifies when a host, previosly scanned, has changes both on the number of open ports and on the CVEs found.

The Alert is sent when at least one of these two has changed.

The Alert can be found in the Active Monitoring alert section.

*Category: CyberSecurity*

*Enabled by Default*