# ASN Lookup

> Use this tool when you need to investigate IP addresses and identify their associated Autonomous System Number (ASN) and organization name. The ASN Lookup tool solves problems related to network analysis and security investigations by providing crucial information about IP addresses through the whois.cymru.com service. It takes IP addresses as input and returns ASN and organization name as output, making it a valuable resource for security professionals and AI models during incident response.

Canonical page: https://skillsregistry.net/skills/rossja-asnlookup  
JSON: https://api.skillsregistry.net/v1/skills/rossja-asnlookup

## Description

IR Toolshed MCP Server provides network analysis tools for security professionals, enabling AI models like Claude to perform lookups and analyses during security investigations. The server currently implements an ASN lookup tool that returns information about IP addresses including AS number and organization name, using the whois.cymru.com service. Future plans include adding DNS lookups, WHOIS record retrieval, IP geolocation, and other network analysis capabilities to create a general-purpose service for network incident responders.

## Trust

- **Trust score (0–1):** 0.50
- **Verification tier:** unverified

## Facts

- **Version:** 1.0.0
- **Skill type:** atomic
- **Execution layer:** mcp-remote
- **Runtime environment:** api
- **Category:** security
- **Updated:** 2026-04-25

## Source

- **Source listing:** [PulseMCP](https://www.pulsemcp.com/servers/rossja-asnlookup)
- **Repository:** <https://github.com/rossja/irtoolshed-mcp-server>

## Use it

Resolve this record through the SkillsRegistry MCP server (no auth, read-only):

```
claude mcp add --transport http --scope user skillsregistry https://api.skillsregistry.net/mcp
```

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "get_skill",
    "arguments": {
      "slug": "rossja-asnlookup"
    }
  }
}
```

REST: `GET https://api.skillsregistry.net/v1/skills/rossja-asnlookup` · pull for local use: `GET https://api.skillsregistry.net/v1/skills/rossja-asnlookup/pull`

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SkillsRegistry indexes agent skills from public registries and GitHub. Skills we have analysed are scanned with Circle-IR and scored on six dimensions; each listing states its scan coverage. More: https://skillsregistry.net/llms.txt