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OSSEC / HIDS Rule 504
- Rule family: OSSEC / HIDS
- Rule ID: 504
- Definition status: Present in current source
- Alert message / subject: Ossec agent disconnected.
- Rule level: 3
- Definition checked: 2026-10-21
Interpretation and response
This event is recorded as “Ossec agent disconnected.” Review the originating log and the affected host or service to determine whether the activity was expected.
An OSSEC/HIDS event records or correlates activity. Blocking depends on the originating application and any separately configured Active Response policy; an alert alone does not prove that an attack was blocked.
Documentation
The following guidance was migrated from the historical wiki and reviewed against the rule definition. Legacy ASL product names and interface instructions refer to the versions documented then. Use the current metadata above and your installed configuration when interpreting thresholds, notification settings and response behavior.
Description
An agent has disconnected from the server.
What you should do
This is an internal tracking rule. It could indicate a network issue between the agent and the server (Default: UDP 1514). Investigate the agent to ensure why it is offline.
Troubleshooting
False Positives
A legitimate event may still trigger this rule. Review the surrounding activity before deciding whether it is malicious.
Tuning Guidance
There is no guidance for tuning this rule, this is a generic ossec event and the rule should not be disabled.
Additional Information
Support
If you are unsure about how to respond to this alert, please contact Atomicorp support. We’re here to help you!
Source and revision
Migrated from HIDS_504, wiki page 846, revision 6211 (20201022). Documentation review: 2026-10-21. An archived wiki status of Active is not a current deployment status.
For assistance, provide the rule ID, installed product and rule version, and a sanitized event to Atomicorp support .