AI agents call opn_list_dnsbl 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.
The 'list_' prefix and context of DNSBL (DNS blocklist configuration) indicate this tool retrieves or enumerates existing DNS blocklist settings without modifying them. No side effects or destructive actions are evident. Classified as Read with low severity since it only queries configuration data.
From the tool's definition Tool name 'opn_list_dnsbl' indicates a listing/querying operation (list); DNSBL is DNS Blacklist, a data retrieval function. Description is empty, reducing confidence slightly.
Documented attack patterns abuse exactly the kind of access opn_list_dnsbl 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 opn_list_dnsbl:
{
"version": "1",
"default": "deny",
"tools": {
"opn_list_dnsbl": {}
}
}opn_list_dnsbl is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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opn_list_dnsbl. 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 opn_list_dnsbl: 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.
opn_list_dnsbl 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 opn_list_dnsbl 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 opn_list_dnsbl. 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.
opn_list_dnsbl is provided by the OPNsense MCP Server MCP server (lucamarien/opnsense-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from OPNsense MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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81 OPNsense MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.