AI agents use opn_add_dns_override to create or update resources in OPNsense MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your OPNsense MCP Server environment.
DNS overrides modify DNS resolution behavior by adding custom mappings, which is a reversible configuration change (Write category). Severity is high because misconfigured DNS overrides can redirect traffic to malicious hosts, intercept communications, or cause widespread network connectivity issues.
From the tool's definition Tool name 'opn_add_dns_override' explicitly indicates creation/addition of a DNS override entry. No description provided, but the naming pattern matches sibling tools like 'opn_add_alias', 'opn_add_firewall_rule', and 'opn_add_nat_rule' which create new…
Documented attack patterns abuse exactly the kind of access opn_add_dns_override 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_add_dns_override:
{
"version": "1",
"default": "deny",
"tools": {
"opn_add_dns_override": {
"limits": [
{
"counter": "opn_add_dns_override_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}opn_add_dns_override stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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opn_add_dns_override. It is categorised as a Write tool in the OPNsense MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the OPNsense MCP Server MCP server in PolicyLayer and add a rule for opn_add_dns_override: 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_add_dns_override is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the opn_add_dns_override 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_add_dns_override. 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_add_dns_override 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.