change_phj_destination · Firegex MCP: Risk & Policy

WHAT IT DOES

What change_phj_destination does on Firegex

AI agents use change_phj_destination 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 change_phj_destination needs a policy

This tool modifies an existing network firewall/proxy rule by changing its destination IP and port. It is a reversible configuration change (Write), but carries high severity because misconfiguring network routing rules could redirect traffic to attacker-controlled destinations, exposing sensitive communications or bypassing security controls.

From the tool's definition Repoint an existing porthijack rule to a new ip_dst:proxy_port

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

change_phj_destination Rate-limited

change_phj_destination 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": {
    "change_phj_destination": {
      "limits": [
        {
          "counter": "change_phj_destination_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 change_phj_destination

What does the change_phj_destination tool do? +

Repoint an existing porthijack rule to a new ip_dst:proxy_port. 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 change_phj_destination? +

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

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

Can I rate-limit change_phj_destination? +

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

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

change_phj_destination 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.