# external\_1801 **Explanation** The external\_1801 NDM flags connections from outside the customer network to servers on the customer network listening with TCP or UDP on port 1801. Microsoft Message Queuing is a messaging protocol that allows applications running on different servers to communicate. It uses port 1801. **What to Look For** Under most circumstances, Microsoft Message Queuing is not a service that should be exposed to external hosts. Verify that the host in question is properly protected by firewall policies. This NDM could false positive in situations where the customer's internal network IP address ranges have not been properly configured in Netography Fusion. **Related MITRE ATT\&CK Categories** [Initial Access: Exploit Public-Facing Application, Technique T1190 - Enterprise](https://attack.mitre.org/techniques/T1190) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.fusion.vectra.ai/detection-models/library/operational-governance/external_1801.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.