AI agents call list_dns_blocklist 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 tool performs a query/retrieval action with no side effects. It simply enumerates DNS blocklist entries for visibility into firewall configuration, similar to a 'list' or 'get' operation. There is no creation, modification, deletion, or execution of external operations involved.
From the tool's definition Tool name 'list_dns_blocklist' and description 'List all DNS blocklist entries' indicate a read-only operation that retrieves existing blocklist data without modification.
Documented attack patterns abuse exactly the kind of access list_dns_blocklist 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 list_dns_blocklist:
{
"version": "1",
"default": "deny",
"tools": {
"list_dns_blocklist": {}
}
}list_dns_blocklist 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 DNS blocklist entries. 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 list_dns_blocklist: 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.
list_dns_blocklist 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 list_dns_blocklist 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 list_dns_blocklist. 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.
list_dns_blocklist 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.