set_pyfilter_code_from_file · Firegex MCP: Risk & Policy

WHAT IT DOES

What set_pyfilter_code_from_file does on Firegex

AI agents use set_pyfilter_code_from_file to create or update resources in Firegex — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Firegex environment.

WHY IT NEEDS A POLICY

Why set_pyfilter_code_from_file needs a policy

This tool creates or modifies firewall filter rules by uploading Python code to Firegex. While not destructive (the change is reversible via deletion or update), it is clearly a Write operation that alters security-critical firewall state. Severity is high because misuse could disable or weaken security controls, affect network traffic routing, or introduce malicious filtering logic into a CTF/proxy firewall system.

From the tool's definition Tool description states 'Load Python filter code from a local file and push it to Firegex.' The verb 'push' indicates modification of firewall configuration on a live system. The tool modifies filter rules rather than merely reading them.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_pyfilter_code_from_file Rate-limited

set_pyfilter_code_from_file stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_pyfilter_code_from_file": {
      "limits": [
        {
          "counter": "set_pyfilter_code_from_file_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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 set_pyfilter_code_from_file

What does the set_pyfilter_code_from_file tool do? +

Load Python filter code from a local file and push it to Firegex. It is categorised as a Write tool in the Firegex MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_pyfilter_code_from_file? +

Register the Firegex MCP server in PolicyLayer and add a rule for set_pyfilter_code_from_file: 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 set_pyfilter_code_from_file? +

set_pyfilter_code_from_file is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_pyfilter_code_from_file? +

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

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

set_pyfilter_code_from_file 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.