check_vnc

Connect to a VNC server and read the RFB protocol banner. Returns whether the server is reachable, the RFB version string (e.g. 'RFB 003.008'), and the supported security types. Does not authenticate. port: 5900 (default), 5901, 5902, etc. Useful for verifying remote desktop service availability.

SERVERMcp Nettools SOURCEaaronckj/mcp-nettools

Low RISK CLASS

Category Read

Parameters 00 required

Recommended Allowedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/aaronckj-mcp-nettools/check-vnc.md

WHAT IT DOES

What check_vnc does on Mcp Nettools

AI agents call check_vnc to retrieve information from Mcp Nettools without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

RISK

Why check_vnc is rated Low

This tool retrieves information about VNC server configuration and availability via banner grabbing. While it connects to and probes a remote service, it does not execute commands, modify data, or cause destructive changes. The 'Read' category applies because it queries service metadata.

From the tool's definition Tool performs 'Connect to a VNC server and read the RFB protocol banner' without authentication, returning version strings and supported security types. No modification, execution, or deletion occurs.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs check_vnc safely

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

check_vnc Allowed

check_vnc is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "check_vnc": {}
  }
}

ALLOW ONLY THIS TOOL → Instant setup, no code required.

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

FAQ

Questions about check_vnc

What does the check_vnc tool do? +

How do I enforce a policy on check_vnc? +

Register the Mcp Nettools MCP server in PolicyLayer and add a rule for check_vnc: 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 Mcp Nettools. Nothing to install.

What risk level is check_vnc? +

check_vnc is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit check_vnc? +

Yes. Add a rate_limit block to the check_vnc 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 check_vnc completely? +

Set action: deny in the PolicyLayer policy for check_vnc. 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 check_vnc? +

check_vnc is provided by the Mcp Nettools MCP server (aaronckj/mcp-nettools). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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