{
  "port": 9877,
  "protocol": "tcp",
  "service": "x510 — X.510 wrapper protocol",
  "oneLiner": "The ITU-T X.510 wrapper protocol for secure directory operations — registered in 2019, seldom seen outside PKI and directory products.",
  "whatItIs": "IANA registered 9877/tcp as `x510` in 2019 on behalf of ITU-T Study Group 17, referencing ITU-T X.510 / ISO/IEC 9584-11, \"Protocol specifications for secure operations\" in the OSI Directory series. The wrapper protocol carries authenticated and integrity-protected directory operations, and shows up in X.500-lineage directory and PKI implementations rather than general infrastructure. UDP 9877 is Reserved. On a typical network this port is empty.",
  "exposure": {
    "verdict": "careful",
    "note": "The protocol is designed with its own authentication and integrity protection, but a directory service is still directory data. Expose it only if you have deliberately deployed X.510 and configured its trust anchors."
  },
  "checkCommand": "nc -vz TARGET 9877",
  "links": [
    {
      "title": "ITU-T Recommendation X.510 — Protocol specifications for secure operations",
      "url": "https://www.itu.int/rec/T-REC-X.510/en",
      "kind": "spec"
    },
    {
      "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"
    }
  ]
}