Port 2393: MS OLAP 1 — The Registered Port That Went Nowhere

What This Port Is

Port 2393 sits in the registered ports range (1024–49151) — the middle tier of the port number space, between the well-known ports (0–1023) that require root privileges and the ephemeral ports (49152–65535) used for temporary outbound connections.

IANA has assigned port 2393 to MS OLAP 1, registered by Mosha Pasumansky at Microsoft, for both TCP and UDP. That sounds official. In practice, it's a historical artifact.

The OLAP Story

In 1998, Microsoft shipped OLAP Services as part of SQL Server 7.0 — their entry into the business intelligence and multidimensional data market. When they registered ports for it, they reserved a cluster: port 2383 for the primary service, and port 2393 as a sibling.¹

By SQL Server 2000, OLAP Services was renamed Analysis Services. By SQL Server 2005, the architecture had matured. Through all of it, port 2383 became the standard — the port that firewall rules reference, that DBAs configure, that connection strings point to.²

Port 2393 kept its IANA registration. Nothing meaningful ever ran on it.

Is Anything Using This Port Today?

Occasionally. If you see traffic on port 2393, the most likely explanations are:

• Custom applications — developers sometimes pick registered-but-unused ports for their own services, assuming "IANA assigned" means "safe to use"
• Malware — uncommon ports with legitimate-sounding names occasionally appear in threat reports
• Misconfigured Analysis Services — rare, but possible if a DBA manually pointed SSAS at the wrong port

None of these are common. Port 2393 is mostly quiet.

How to Check What's Listening

If you see activity on this port and want to know what's there:

# On Linux/macOS
ss -tlnp | grep 2393
# or
lsof -i :2393

# On Windows
netstat -ano | findstr :2393
# Then look up the PID:
tasklist | findstr <PID>

Why This Matters

The IANA registry contains thousands of registered ports that never became anything. A company or developer files for a number, reserves it with a name, and then the product changes direction — or ships, but uses a different port, or dies entirely.

Port 2393 is a small illustration of how the port space works in practice: official assignment doesn't mean active use, and a name in a registry doesn't mean a protocol in the wild.

The Internet's port space is full of these ghosts — numbers that belong to something on paper but carry nothing across a wire.