{
  "port": 4126,
  "protocol": "tcp",
  "service": "Data Domain Replication Service (ddrepl)",
  "oneLiner": "Registered by Data Domain for appliance-to-appliance backup replication; rare on scans.",
  "whatItIs": "IANA carries 4126 as ddrepl, the Data Domain Replication Service, registered by Data Domain — now Dell's deduplicating backup appliance line. DD Replicator copies deduplicated backup data between appliances for disaster recovery. Scan data puts the port in the noise, and current Data Domain deployment guides route replication over other ports, so a listener here is worth confirming against the appliance's own configuration rather than assumed.",
  "exposure": {
    "verdict": "never",
    "note": "Backup-appliance replication traffic is a path to an organisation's entire backup corpus; it belongs on a private link or VPN between sites."
  },
  "checkCommand": "nc -vz -w 3 TARGET 4126",
  "links": [
    {
      "title": "IANA port registry — 4126 (ddrepl, Data Domain Replication Service)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=4126",
      "kind": "iana"
    }
  ]
}