Definition - What does Promiscuous Mode mean?
Promiscuous mode is a type of computer networking operational mode in which all network data packets can be accessed and viewed by all network adapters operating in this mode. It is a network security, monitoring and administration technique that enables access to entire network data packets by any configured network adapter on a host system.
Promiscuous mode is used to monitor traffic.
Techopedia explains Promiscuous Mode
In promiscuous mode, a network adapter does not filter packets. Each network packet on the network segment is directly passed to the operating system (OS) or any monitoring application. If configured, the data is also accessible by any virtual machine (VM) or guest OS on the host system.
Typically, promiscuous mode is used and implemented by a snoop program that captures all network traffic visible on all configured network adapters on a system. Because of its ability to access all network traffic on a segment, promiscuous mode is also considered unsafe. Like a system with multiple VMs, each host has the ability to see network packets destined for other VMs on that system.