fin_scan

Perform a FIN scan on the specified target with optional custom arguments.

SERVERNmapMCP SOURCE0xpratikpatil/nmapmcp

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/0xpratikpatil-nmapmcp/fin-scan.md

WHAT IT DOES

What fin_scan does on NmapMCP

AI agents invoke fin_scan to trigger actions in NmapMCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

RISK

Why fin_scan is rated High

A FIN scan sends crafted TCP packets to probe remote systems for open ports while evading firewalls/IDS. This is an active network reconnaissance operation with real external effects (packets sent to targets), making it Execute. It can be used for unauthorized network probing, giving it high severity. It is not Destructive (no data is deleted) but does trigger external operations whose effects depend on arguments.

From the tool's definition "Perform a FIN scan on the specified target" — executes a stealth TCP FIN network scan against external hosts

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs fin_scan safely

PolicyLayer is an MCP gateway: it sits between your AI agents and NmapMCP, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For fin_scan, this is the rule to start with:

fin_scan Rate-limited

fin_scan stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "fin_scan": {
      "limits": [
        {
          "counter": "fin_scan_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect NmapMCP, apply this rule, and every fin_scan call is checked against it from then on.

FAQ

Questions about fin_scan

What does the fin_scan tool do? +

Perform a FIN scan on the specified target with optional custom arguments. It is categorised as a Execute tool in the NmapMCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on fin_scan? +

Register the Nmap MCP server in PolicyLayer and add a rule for fin_scan: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches NmapMCP. Nothing to install.

What risk level is fin_scan? +

fin_scan is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit fin_scan? +

Yes. Add a rate_limit block to the fin_scan rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block fin_scan completely? +

Set action: deny in the PolicyLayer policy for fin_scan. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides fin_scan? +

fin_scan is provided by the Nmap MCP server (0xpratikpatil/nmapmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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