tcp_banner

Connect to any TCP port and read the initial server banner. Useful for identifying unknown services or verifying custom TCP servers. Returns raw banner text.

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/tcp-banner.md

WHAT IT DOES

What tcp_banner does on Mcp Nettools

AI agents call tcp_banner 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 tcp_banner is rated Low

This tool performs passive information gathering by connecting to TCP ports and reading responses, similar to network reconnaissance. While it can probe any port, it only retrieves existing banner data without side effects, making it a Read operation.

From the tool's definition Tool description states it "Connect[s] to any TCP port and read the initial server banner" and "Returns raw banner text." The core function is retrieval of data (banner information) with no modification, creation, deletion, or code execution.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs tcp_banner 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 tcp_banner, this is the rule to start with:

tcp_banner Allowed

tcp_banner 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": {
    "tcp_banner": {}
  }
}

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 tcp_banner call is checked against it from then on.

FAQ

Questions about tcp_banner

What does the tcp_banner tool do? +

Connect to any TCP port and read the initial server banner. Useful for identifying unknown services or verifying custom TCP servers. Returns raw banner text. It is categorised as a Read tool in the Mcp Nettools MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on tcp_banner? +

Register the Mcp Nettools MCP server in PolicyLayer and add a rule for tcp_banner: 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 tcp_banner? +

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

Can I rate-limit tcp_banner? +

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

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

tcp_banner 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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