Agentless discovery is a way to identify devices, software, and services without installing an endpoint agent on each system. Instead, a security or asset-management platform queries the network or management interfaces directly, using methods such as SSH, WMI, SNMP, APIs, or passive traffic analysis. This is important because many enterprise assets, including switches, printers, IoT sensors, OT systems, and some medical devices, cannot easily run normal management software.
In cyber security, agentless discovery helps teams build an accurate inventory and feed a CMDB or asset graph, which is the basis for patching, policy enforcement, and incident response. It is also useful when organizations need quick visibility into unmanaged or shadow IT devices. The downside is that it depends on network reachability and credentials, and it may miss details that an installed agent would collect. Attackers benefit when defenders lack this visibility, because hidden or unknown devices are harder to monitor and isolate.