{
  "port": 42,
  "protocol": "both",
  "service": "Host Name Server / WINS replication",
  "oneLiner": "Registered as the ARPANET Host Name Server; in practice this is Microsoft WINS replication traffic.",
  "whatItIs": "IANA registers 42 under the service names 'name' and 'nameserver' for the Host Name Server, a pre-DNS lookup service that no longer exists in the wild. What actually uses the port today is Windows Internet Name Service replication: WINS servers push and pull NetBIOS name-to-address mappings between each other over TCP 42, and Microsoft's network-port requirements documentation lists the port under WINS. Seeing it open means a Windows Server with the WINS role, which is a deprecated feature kept alive for legacy NetBIOS applications.",
  "exposure": {
    "verdict": "never",
    "note": "Internal Windows name-infrastructure replication with no place on a public interface; keep it inside the network boundary between WINS partners only."
  },
  "checkCommand": "nmap -Pn -sV -p 42 TARGET",
  "links": [
    {
      "title": "Service overview and network port requirements for Windows",
      "url": "https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/service-overview-and-network-port-requirements",
      "kind": "official-docs"
    },
    {
      "title": "IANA Service Name and Transport Protocol Port Number Registry",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml",
      "kind": "iana"
    }
  ]
}