Port 2243: Magicom — The Registered Ghost

Port 2243 exists in an unusual category: it has a name, but the name explains almost nothing.

IANA — the organization that maintains the official registry of port assignments — lists port 2243 as "magicom," assigned to the Magicom Protocol on both TCP and UDP. The registrant is Yossi Appleboum, a cybersecurity professional and co-founder of Sepio Systems, a hardware security company focused on detecting rogue devices at the physical layer.¹

Beyond that, the public record goes silent. There is no RFC. There is no specification. There are no known open-source implementations or production deployments. Whatever Magicom Protocol is or was, it was never documented for public use.

What Range Does Port 2243 Belong To?

Port 2243 falls in the registered ports range: 1024–49151.

This range sits between the well-known ports (0–1023), which are reserved for foundational Internet services like HTTP, DNS, and SSH, and the dynamic/ephemeral ports (49152–65535), which operating systems assign temporarily for outgoing connections.

The registered ports are meant for applications that want a stable, recognized number — something to put in your documentation, tell your firewall team, and reliably find on the other side. To claim a registered port, you submit a request to IANA. The bar is real but not especially high: you need a contact, a service name, and a transport protocol. You do not need to publish a specification.²

Port 2243 passed that bar. It has a name on record. But a name without a specification leaves everyone else — network administrators, security teams, curious engineers — with nothing to go on.

Has It Been Observed in the Wild?

Some port databases flag port 2243 with a historical malware association, meaning that at some point in the past, malicious software used this port for command-and-control or data exfiltration. This is not uncommon — malware authors sometimes pick obscure registered ports precisely because they look less suspicious than truly random numbers. Whether any current malware actively uses port 2243 is unknown.

No legitimate application traffic on this port has been publicly documented.

How to Check What's Listening on Port 2243

If you see port 2243 open on a system you manage, check it:

On Linux or macOS:

# Show which process is listening on port 2243
ss -tlnp | grep 2243

# Or using lsof
lsof -i :2243

On Windows:

netstat -ano | findstr :2243

Match the process ID to a running application. If you can't identify the process, treat it with suspicion.

From outside the machine:

# Check if the port is open from another host
nmap -p 2243 <target-ip>

If port 2243 is open and you cannot identify the process responsible, close it. There is no known legitimate service that requires it.

Why Ghost Registrations Matter

The IANA registry is not just a list of active, documented protocols. It is also a record of intentions — ports claimed by companies or individuals who may have planned something that never shipped, or built something they never published.

Ghost registrations like port 2243 create a kind of ambiguity. The port is not unassigned, so it shows up in databases with a name. But the name provides no guidance. Network tools that look up port names will tell you "magicom" and leave you no wiser than before.

This is the quiet failure mode of the registration system: it can tell you who claimed the port, but it cannot tell you what they built, or whether it still exists.