Map domain IPs to Autonomous System Numbers via Team Cymru DNS. Returns ASN, prefix, country, registry, and organization for each IP. Flags high-risk hosting ASNs.
Part of the Blackveil Dns MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.
AI agents call cymru_asn to retrieve information from Blackveil Dns without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though cymru_asn only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
tools:
cymru_asn:
rules:
- action: allowSee the full Blackveil Dns policy for all 51 tools.
Agents calling read-class tools like cymru_asn have been implicated in these attack patterns. Read the full case and prevention policy for each:
Other tools in the Read risk category across the catalogue. The same policy patterns (rate-limit, allow) apply to each.
Map domain IPs to Autonomous System Numbers via Team Cymru DNS. Returns ASN, prefix, country, registry, and organization for each IP. Flags high-risk hosting ASNs.. It is categorised as a Read tool in the Blackveil Dns MCP Server, which means it retrieves data without modifying state.
Add a rule in your Intercept YAML policy under the tools section for cymru_asn. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the Blackveil Dns MCP server.
cymru_asn 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 cymru_asn rule in your Intercept 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 Intercept policy for cymru_asn. 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.
cymru_asn is provided by the Blackveil Dns MCP server (blackveil-dns). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic policy on every MCP tool call. Per-identity grants. Full audit log.