Port 2106: The Door to Lineage II

Port 2106 sits in the registered port range (1024–49151), the middle tier of the port numbering system. These ports don't require administrator privileges to open, and IANA maintains a registry of their assignments — but registration doesn't mean adoption. Port 2106 is a good example of the gap between what IANA registered and what the Internet actually used.

What IANA Registered

IANA assigned port 2106 to MZAP — Multicast Zone Announcement Protocol. MZAP was a protocol proposed in the late 1990s for managing multicast zones on IP networks, described in RFC 2776.¹ It was never widely deployed. The protocol's use case (large-scale multicast routing) found other solutions, and MZAP quietly faded while its port number sat unclaimed in practice.

What the Internet Actually Used

Lineage II used port 2106 for its login server.²

NCSoft's Lineage II, launched in 2003, became one of the most-played MMORPGs in the world — particularly dominant in South Korea, where it had millions of concurrent players at its peak. The architecture was simple: port 2106 handled authentication, and port 7777 handled the game world itself. Every player who ever created a character, entered a password, and stepped into Aden had their login processed on port 2106.

Private server operators running the L2J (Lineage II Java) emulator needed the same ports.³ Forum posts across gaming communities from 2004 onward document the question thousands of server admins asked: "Which ports do I forward?" The answer was always 2106 and 7777.

The port also appears in lists for other NCSoft titles of that era: City of Heroes, City of Villains, and Aion — games that shared infrastructure and port conventions.⁴

A Note on Security

Port scanners sometimes flag port 2106 as associated with historical malware activity. This is true of many ports in the registered range — attackers use unmonitored ports opportunistically. If you see unexpected traffic on port 2106 and you're not running a Lineage II server, investigate it.

How to Check What's Using This Port

If port 2106 appears open on your system and you're not sure why:

On Linux/macOS:

sudo ss -tlnp | grep 2106
# or
sudo lsof -i :2106

On Windows:

netstat -ano | findstr :2106
# Then look up the PID:
tasklist | findstr <PID>

If nothing shows up, the port isn't in use. If something does, the process name will tell you what claimed it.

Why Unassigned Ports Matter

Most ports in the registered range have this same story: an IANA registration that reflects an era's concerns, and real-world usage that evolved independently. The registry is a record of intent, not a description of reality. Port 2106 was meant for multicast zone management. It became the login door for a fantasy world where millions fought dragons. The Internet doesn't always follow the plan.