firewall_add_rule

Add a new firewall rule

SERVEROPNsense MCP Server SOURCEfakebizprez/opnsense-mcp-server

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/fakebizprez-opnsense-mcp-server/firewall-add-rule.md

WHAT IT DOES

What firewall_add_rule does on OPNsense MCP Server

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

RISK

Why firewall_add_rule is rated Medium

This tool creates new firewall rules, which is a Write operation (creates/modifies data reversibly). It is not Destructive (rules are not irreversibly deleted), not Execute (does not run arbitrary code—it configures a specific firewall construct), not Financial, and not Read.

From the tool's definition Tool name 'firewall_add_rule' and description 'Add a new firewall rule' indicate creation of a new firewall configuration rule.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs firewall_add_rule safely

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

firewall_add_rule Rate-limited

firewall_add_rule 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": {
    "firewall_add_rule": {
      "limits": [
        {
          "counter": "firewall_add_rule_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect OPNsense MCP Server, apply this rule, and every firewall_add_rule call is checked against it from then on.

FAQ

Questions about firewall_add_rule

What does the firewall_add_rule tool do? +

Add a new firewall rule. It is categorised as a Write tool in the OPNsense MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on firewall_add_rule? +

Register the OPNsense MCP Server MCP server in PolicyLayer and add a rule for firewall_add_rule: 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 OPNsense MCP Server. Nothing to install.

What risk level is firewall_add_rule? +

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

Can I rate-limit firewall_add_rule? +

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

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

firewall_add_rule is provided by the OPNsense MCP Server MCP server (fakebizprez/opnsense-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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