Port 2335: Unassigned — An empty address in the registered range

Port 2335 belongs to the registered port range (1024-49151). IANA tracks this range, but tracking and assigning are different things. Port 2335 was never assigned to any protocol or service. As of 2026, IANA lists it as unassigned.¹

What the Registered Range Means

The Internet has 65,535 ports. They're divided into three zones:

• Well-known ports (0-1023): Reserved for foundational protocols — HTTP on 80, HTTPS on 443, SSH on 22. Require elevated privileges to bind on most systems.
• Registered ports (1024-49151): Claimed by applications that registered them with IANA. Oracle uses 1521. MySQL uses 3306. But thousands of numbers in this range were never claimed by anyone.
• Dynamic/ephemeral ports (49152-65535): Temporary ports assigned by the OS when your computer initiates a connection. Nobody registers these.

Port 2335 sits in the registered range. It just never got registered.

The Only Known History Here: IRCContact

The one documented use of port 2335 is not something to admire. The IRCContact trojan — a backdoor from the early 2000s IRC malware era — used a cluster of ports from 2330 through 2335 for command-and-control communication.²

IRC trojans worked by connecting infected machines to attacker-controlled IRC channels. The attacker sent commands; the trojan executed them. Choosing obscure, unassigned ports was the strategy: no legitimate service would be listening there, so the traffic was less likely to trigger alerts.

Port 2335 was, in other words, chosen precisely because nothing legitimate lived there.

How to Check What's Listening on Port 2335

If you see activity on port 2335 and want to know what's causing it:

macOS / Linux:

lsof -i :2335

Windows:

netstat -ano | findstr :2335

Then cross-reference the PID with Task Manager or:

tasklist | findstr <PID>

All platforms (if you have nmap):

nmap -sV -p 2335 localhost

Unexpected activity on this port is worth investigating. Nothing legitimate should be binding here.

Why Unassigned Ports Matter

Unassigned ports reveal something real about how the Internet grew. The port number space was designed for orderly registration, but the Internet moved faster than any registry could track. Applications picked numbers, protocols were invented, software shipped — and IANA's list of assignments never caught up.

The result: thousands of ports in the registered range that are technically unassigned but in active use somewhere. And thousands more that are genuinely empty — dark corners where only the stealthy or careless venture.

Port 2335 is one of the empty ones. The kind of port where, if you see something moving, you should ask why.