whatismynetip

netip-mcp

The whatismynetip.com toolbox as tools your coding agent can call. Subnet math, "what runs on this port and should it be open", MAC vendor lookups, DNS and blocklist checks, the certificate a host actually serves, and the IP the internet sees you as.

Free, MIT, no account, no telemetry. The site's own tools run in your browser; this runs the same logic next to your agent.

Install

Pin the version.

Claude Code

claude mcp add netip -- npx -y github:getlarkwright/netip-mcp#v0.1.1

Claude Desktop, Cursor, or any client with a JSON config

{
  "mcpServers": {
    "netip": {
      "command": "npx",
      "args": ["-y", "github:getlarkwright/netip-mcp#v0.1.1"]
    }
  }
}

Docker

{
  "mcpServers": {
    "netip": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "ghcr.io/getlarkwright/netip-mcp:0.1.1"]
    }
  }
}

Node 18 or newer for the npx route. Also in the official MCP registry as io.github.getlarkwright/netip-mcp.

Tools

Tool	What it answers	Network
subnet_calc	Network, mask, wildcard, broadcast, host range and counts for a CIDR — IPv4 and IPv6, /31 and /32 done right	none
ip_in_subnet	Is this address inside that block?	none
ip_convert	IPv4 as dotted, integer, hex, binary — from any of them	none
ipv6_normalize	Expanded and RFC 5952 compressed forms, and what kind of address it is	none
mac_lookup	Vendor from the full IEEE registry (~40,000 assignments, bundled), plus the multicast and locally-administered bits	none
lookup_port	What runs on a port, and whether to expose it — 100 ports written up by hand, searchable by service	none
dns_lookup	A, AAAA, MX, TXT, NS, CNAME, CAA, SOA, PTR, SRV over DNS-over-HTTPS	DoH
reverse_dns	PTR for an IPv4 or IPv6 address	DoH
dnsbl_check	Five common blocklists, honest about the ones that refuse public resolvers	DoH
tls_inspect	The certificate a host actually serves: expiry, SANs, chain verification, protocol, cipher	direct TLS
my_public_ip	The address the internet sees, edge location, ASN, reverse DNS, datacenter/VPN hint	Cloudflare trace + Team Cymru DNS

lookup_port

The one I reach for most. The port pages on the site are opinionated — every port carries a verdict:

Port 3389/tcp+udp — RDP (Remote Desktop Protocol)

  Category   remote access
  Software   Windows Remote Desktop Services, xrdp, FreeRDP server, Windows Admin Center hosts
  Exposure   NEVER — do not expose to the internet

Internet-facing RDP is the most common initial-access route for ransomware crews, who
credential-stuff it around the clock; put it behind WireGuard, Tailscale or an RD Gateway …

Ask by number, or search: lookup_port with query: "redis" finds 6379. detail: true adds the full write-up and FAQ.

What it does not do

• No account, no signup, no key.
• No telemetry. Nothing about your usage goes anywhere.
• Nothing of yours is read from disk. The only file it opens is its own bundled OUI table.
• The local tools never open a socket. The network tools talk only to public services — Cloudflare and Google's DNS-over-HTTPS resolvers, Cloudflare's trace endpoint, Team Cymru's ASN DNS, and whichever host you point tls_inspect at. tls_inspect refuses anything that resolves to private or reserved space, so it cannot be turned on your own network.
• "Is my port reachable from outside?" needs a machine outside your NAT to try the connection. That is what whatismynetip.com/port-checker does; a local tool cannot.

The port data and the calculators are the same ones the site uses, so the two stay in step.

Licence

MIT © Larkwright LLC. Written by James Son — network, security, and automation engineer. Corrections and additions to the port write-ups are welcome.