new_fqdns

THE RISK

Low Risk

Why new_fqdns needs a policy

This tool queries the Censys Search API to retrieve recently observed fully qualified domain names associated with a given domain. It only reads/fetches data from DNS and certificate records with no side effects, modifications, or destructive actions.

From the tool's definition Find recently seen FQDNs tied to a domain in DNS and certs

Documented attack patterns abuse exactly the kind of access new_fqdns gives an agent:

POLICY

How to control new_fqdns

PolicyLayer is an MCP gateway — it sits between your AI agents and MCP-Censys, and nothing reaches the server without passing your rules. This is the rule we recommend for new_fqdns:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "new_fqdns": {}
  }
}

new_fqdns is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

Create a free account and register MCP-Censys — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More MCP-Censys tools

Read host_services List exposed ports and service names for a given IP address. Read lookup_domain Summarize a domain Read lookup_domain_detailed Return full host records for a domain (services, ASN, geo, TLS). Shows a limited sample of Read lookup_ip Get full metadata for an IP: DNS, ASN, ports, TLS, and location.

All 5 MCP-Censys tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about new_fqdns

What does the new_fqdns tool do? +

Find recently seen FQDNs tied to a domain in DNS and certs. It is categorised as a Read tool in the MCP-Censys MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on new_fqdns? +

Register the MCP-Censys MCP server in PolicyLayer and add a rule for new_fqdns: 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 MCP-Censys. Nothing to install.

What risk level is new_fqdns? +

new_fqdns is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit new_fqdns? +

Yes. Add a rate_limit block to the new_fqdns 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.

How do I block new_fqdns completely? +

Set action: deny in the PolicyLayer policy for new_fqdns. 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.

What MCP server provides new_fqdns? +

new_fqdns is provided by the MCP-Censys MCP server (nickpending/mcp-censys). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP-Censys tool call.

Start from MCP-Censys, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →