{
  "port": 6600,
  "protocol": "tcp",
  "service": "MPD / Hyper-V Live Migration",
  "oneLiner": "Music Player Daemon's control port in practice; registered to Microsoft for Hyper-V Live Migration.",
  "whatItIs": "IANA registered 6600/tcp in 2009 as mshvlm, Microsoft Hyper-V Live Migration — the channel that carries a running VM's memory between cluster hosts. On Linux and macOS boxes, though, an open 6600 is almost always MPD, the Music Player Daemon: its documentation states that if no port is specified the default is 6600. MPD speaks a simple line-based text protocol that greets you with \"OK MPD <version>\" and then accepts library and playback commands, with a password being optional.",
  "exposure": {
    "verdict": "never",
    "note": "MPD's protocol is cleartext and unauthenticated unless you configure a password, and it exposes your library paths and playback control. Hyper-V live migration traffic is cluster-internal by design. Neither belongs on a public IP."
  },
  "checkCommand": "printf 'status\\nclose\\n' | nc TARGET 6600",
  "links": [
    {
      "title": "MPD User Manual — configuration and the default port",
      "url": "https://mpd.readthedocs.io/en/latest/user.html",
      "kind": "official-docs"
    },
    {
      "title": "Music Player Daemon source repository",
      "url": "https://github.com/MusicPlayerDaemon/MPD",
      "kind": "github"
    },
    {
      "title": "IANA Service Name and Transport Protocol Port Number Registry — 6600 (mshvlm)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=6600",
      "kind": "iana"
    }
  ]
}