{
  "port": 3918,
  "protocol": "tcp",
  "service": "PacketCable Multimedia COPS",
  "oneLiner": "The COPS channel a cable policy server uses to install QoS gates on a CMTS under PacketCable Multimedia.",
  "whatItIs": "IANA registers 3918 as pktcablemmcops. In a PacketCable Multimedia deployment an application manager asks a policy server for bandwidth on a subscriber's cable modem, and the policy server pushes that decision to the CMTS as a COPS Gate-Set message; Cisco's CMTS documentation states plainly that COPS sessions on PCMM use TCP port 3918 by default. This is distinct from PacketCable DQoS, which uses a different port. You will only find 3918 inside a cable operator's network, between policy servers and CMTS routers.",
  "exposure": {
    "verdict": "never",
    "note": "Whoever can speak COPS to this port can allocate QoS on a subscriber's service — an operator control plane that must stay inside the operator's own network."
  },
  "checkCommand": "nc -vz TARGET 3918",
  "links": [
    {
      "title": "Cisco cBR — PacketCable and PacketCable Multimedia (COPS sessions on PCMM use TCP 3918)",
      "url": "https://www.cisco.com/c/en/us/td/docs/cable/cbr/configuration/guide/b_docsis_packetcable_pktcblmultimedia_xe17_3/pktcbl.html",
      "kind": "official-docs"
    },
    {
      "title": "RFC 2748 — The COPS (Common Open Policy Service) Protocol",
      "url": "https://www.rfc-editor.org/rfc/rfc2748.html",
      "kind": "spec"
    },
    {
      "title": "IANA port registry — 3918 (pktcablemmcops)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=3918",
      "kind": "iana"
    }
  ],
  "ianaName": "pktcablemmcops"
}