> For the complete documentation index, see [llms.txt](https://docs.fusion.vectra.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fusion.vectra.ai/detection-models/library/operational-governance/unusual_open_tcp_ports.md).

# 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)


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