# WHATPORT(4126)

## NAME

port 4126 — Data Domain Replication Service (ddrepl) — Registered by Data Domain for appliance-to-appliance backup replication; rare on scans.

Protocol: TCP  
IANA registry

## DESCRIPTION

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

**Do not expose.** Backup-appliance replication traffic is a path to an organisation's entire backup corpus; it belongs on a private link or VPN between sites.

## CHECK

```sh
nc -vz -w 3 TARGET 4126
```

## SEE ALSO

- iana — [IANA port registry — 4126 (ddrepl, Data Domain Replication Service)](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=4126) (iana.org)

---

HTML: <https://whatport.net/4126/> · JSON: <https://whatport.net/4126.json> · full dataset: <https://whatport.net/ports.json>