# WHATPORT(3372)

## NAME

port 3372 — MSDTC / TIP 2 — The TIP listener of Microsoft's Distributed Transaction Coordinator — a Windows transaction plane, not an application port.

Protocol: TCP/UDP  
IANA registry

## DESCRIPTION

IANA registers 3372 as tip2 (Transaction Internet Protocol), and Microsoft's MSDTC service listens there for its TIP transaction-manager facet, which lets a Windows transaction coordinator interoperate with non-Microsoft transaction managers. You will see it on SQL Server boxes, BizTalk hosts, and COM+ application servers where distributed transactions are enabled; MSDTC's main OleTx traffic still goes through the RPC endpoint mapper on 135 plus a dynamic port. A configuration flag controls whether the TIP facet will accept a connection from a source port other than 3372.

## EXPOSURE

**Do not expose.** This is a transaction-control plane between trusted servers, historically a DoS target, and it pairs with RPC on 135 — keep it on an internal segment behind a firewall rule that names the specific peer hosts.

## CHECK

```sh
nc -vz -w 3 TARGET 3372
```

## SEE ALSO

- spec — [[MS-DTCM]: MSDTC Connection Manager — OleTx Transaction Internet Protocol](https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-dtcm/afe8d1f8-880e-4c03-a303-cec26e5d148d) (learn.microsoft.com)
- docs — [Configure Distributed Transaction Coordinator (DTC) to work through a firewall](https://learn.microsoft.com/en-us/troubleshoot/windows-server/application-management/configure-dtc-to-work-through-firewalls) (learn.microsoft.com)
- iana — [IANA port registry — 3372 (tip2)](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=3372) (iana.org)

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