AI agents call firewall_list_rules to retrieve information from OPNSense MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only retrieves and displays existing firewall rules without creating, modifying, deleting, or executing any changes. It is a read-only operation with no side effects, matching the Read category definition of 'retrieves or queries data; no side effects (search, list, get, fetch)'.
From the tool's definition Tool name 'firewall_list_rules' and description 'List all firewall rules' indicate a query/retrieval operation with no modification or execution of rules.
Documented attack patterns abuse exactly the kind of access firewall_list_rules gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and OPNSense MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for firewall_list_rules:
{
"version": "1",
"default": "deny",
"tools": {
"firewall_list_rules": {}
}
}firewall_list_rules is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all firewall rules. It is categorised as a Read tool in the OPNSense MCP Server MCP Server, which means it retrieves data without modifying state.
Register the OPNSense MCP Server MCP server in PolicyLayer and add a rule for firewall_list_rules: 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.
firewall_list_rules is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the firewall_list_rules 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.
Set action: deny in the PolicyLayer policy for firewall_list_rules. 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.
firewall_list_rules is provided by the OPNSense MCP Server MCP server (vespo92/opnsensemcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 196 OPNSense MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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196 OPNSense MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.