The Minary plugins are dynamically loaded library files to extend Minary's capabilities. Minary only spoofs target systems within the same LAN, then reroutes and sniffs packets sent to/originating from these systems. Any further processing and evaluation of the sniffed data packets is outsourced to these extension plugins.
A passive plugin only evaluates the data packets it receives from the Minary sniffer module. It extracts information like DNS requests/responses, HTTP requests or login credentials a user sent to a server. All this data is displayed in a separate plugin tab inside the Minary GUI.
An active plugin, besides parsing and interpreting data packets, also modifies packet content. These modifications don't serve to attack a client/server system. They rather support the attacks that are conducted by the intrusive plugins. Examples of active plugins are the firewall or the DNS poisoning plugins.
An intrusive plugin's purpose is to attack a client/server system. It can weaken a system's security measures, inject malicious code into it or exploit existing vulnerabilities. Examples of such plugins are the SSLStrip or the InjectPayload plugins.