AI agents call find_arp_by_ip 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 performs a read-only query operation on ARP (Address Resolution Protocol) tables. It retrieves network diagnostic information (IP-to-MAC address mappings) based on search parameters, with no side effects, data modification, or execution of external commands. The blast radius is minimal—misuse would only expose existing network mapping data already visible within the network.
From the tool's definition Tool name 'find_arp_by_ip' and description 'Find ARP entries by IP address or subnet' indicate a query/lookup operation that retrieves existing ARP table data without modification.
Documented attack patterns abuse exactly the kind of access find_arp_by_ip 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 find_arp_by_ip:
{
"version": "1",
"default": "deny",
"tools": {
"find_arp_by_ip": {}
}
}find_arp_by_ip is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Find ARP entries by IP address or subnet. 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 find_arp_by_ip: 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.
find_arp_by_ip 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 find_arp_by_ip 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 find_arp_by_ip. 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.
find_arp_by_ip 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.