Passiveagentless

Passiveagentless refers to data collection and monitoring approaches that do not install software agents on target systems and rely instead on passive observation of external data sources. In a passive agentless model, visibility is gained from network traffic, log streams, and other shared data feeds rather than active probing or locally installed instrumentation.

How it works involves aggregating information from sources such as network taps or span/mirror ports, flow records (NetFlow, IPFIX, sFlow), and centralized log streams (syslog, security information and event management systems). Collectors or SIEM platforms correlate and present this data without requiring agents on endpoints. This approach often complements or replaces agent-based methods in environments where agent deployment is impractical or restricted.

Benefits of passive agentless monitoring include low overhead on managed devices, easier scalability across large or heterogeneous environments, and suitability for air-gapped or tightly controlled networks. It can reduce security risk by eliminating endpoint software and simplifies deployment in environments with strict change control or vendor lock-in. It also enables broad visibility through standardized data sources.

Limitations and considerations include reduced visibility for endpoints that do not export usable data, potential blind spots in encrypted or private channels, and limited ability to verify endpoint configuration or conduct active checks. Dependency on network infrastructure means visibility can be degraded by topology changes, span port configurations, or missing data sources. Proper data governance and security controls are essential to protect sensitive telemetry.

See also: agent-based monitoring, active monitoring, SNMP, NetFlow/IPFIX/sFlow.