stop_nfregex_service · Firegex MCP: Risk & Policy

WHAT IT DOES

What stop_nfregex_service does on Firegex

AI agents invoke stop_nfregex_service to trigger actions in Firegex. 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.

WHY IT NEEDS A POLICY

Why stop_nfregex_service needs a policy

This tool triggers an external operation that disables a firewall/regex filtering engine. While not irreversible (the service can presumably be restarted), it executes a command with significant side effects: the security posture of the system changes, traffic filtering is disabled, and the blast radius is high if an AI agent misuses it (e.g., to disable protections).

From the tool's definition Stop the nfregex engine (traffic flows through unfiltered) — this action suspends an active security/filtering service and causes a state change with immediate operational consequences (unfiltered traffic bypass).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

stop_nfregex_service Rate-limited

stop_nfregex_service 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": {
    "stop_nfregex_service": {
      "limits": [
        {
          "counter": "stop_nfregex_service_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Firegex, so you can run agents against it safely.

FAQ

Questions about stop_nfregex_service

What does the stop_nfregex_service tool do? +

Stop the nfregex engine (traffic flows through unfiltered). It is categorised as a Execute tool in the Firegex MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on stop_nfregex_service? +

Register the Firegex MCP server in PolicyLayer and add a rule for stop_nfregex_service: 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 Firegex. Nothing to install.

What risk level is stop_nfregex_service? +

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

Can I rate-limit stop_nfregex_service? +

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

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

stop_nfregex_service is provided by the Firegex MCP server (umbra2728/firegex-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.