# unusual\_open\_tcp\_ports **Explanation** The unusual\_open\_tcp\_ports Netography Detection Model (NDM) is designed to detect uncommon TCP ports open and receiving connections on the network. The NDM is triggered when inbound TCP traffic is observed to a port that is unusual and not covered by another NDM that looks for external connections. This event is important because it can indicate when potentially vulnerable services are exposed on the network. **What to Look For** To remediate the issue, administrators should look for any non-standard ports that may be open and receiving incoming connections. They should also analyze endpoint activity to identify any suspicious activity or traffic related to the non-standard port. Applying restrictions on non-essential ports, limiting privileged access to the network, and using strong authentication measures can help prevent unauthorized access attempts. **Related MITRE ATT\&CK Categories** [Initial Access, Persistence: External Remote Services, Technique T1133 - Enterprise](https://attack.mitre.org/techniques/T1133) [Command and Control, Defense Evasion, Persistence: Traffic Signaling, Technique T1205 - Enterprise](https://attack.mitre.org/techniques/T1205) --- # 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/unusual_open_tcp_ports.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.