AI agents call opn_get_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 'get_' prefix combined with the DNSBL (DNS Blocklist) context strongly indicates this is a read-only query tool for retrieving DNS blocklist information or status. No side effects are typical of get operations. Confidence is moderately high despite the empty description because the naming pattern and context within a firewall management server clearly suggest data retrieval rather than modification or execution.
From the tool's definition Tool name 'opn_get_dnsbl' uses the 'get' verb, which conventionally indicates data retrieval without modification. DNSBL (DNS Blocklist) queries are read-only operations that retrieve blocklist status or configuration information.
Documented attack patterns abuse exactly the kind of access opn_get_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_get_dnsbl:
{
"version": "1",
"default": "deny",
"tools": {
"opn_get_dnsbl": {}
}
}opn_get_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_get_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_get_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_get_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_get_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_get_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_get_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.