Port 2035: Unassigned — A Ghost in the Registry

Port 2035 has no officially assigned service. The Internet Assigned Numbers Authority (IANA), which maintains the canonical registry of port-to-service mappings, lists port 2035 as unassigned on both TCP and UDP.¹

The "imsldoc" Ghost

Search port 2035 across the web and you'll find several databases listing it as "imsldoc." The name appears to reference IMS Learning Design — an e-learning specification developed in the early 2000s for describing pedagogical scenarios in online education.²

But here's the honest truth: there is no documented network protocol called imsldoc, no RFC, no specification, and no evidence of any software that has ever actually used port 2035 for this purpose. The name appears to have been added to unofficial port lists at some point and has been copied forward ever since — a rumor that acquired the appearance of fact through repetition.

This is not unusual. Port registries across the web cite each other in loops, and ghost entries accumulate. IANA's own registry — the authoritative source — shows nothing for 2035.

If you see "imsldoc" in a firewall log or port scanner result, it is not a reliable identification. It is a label that port-scanning tools like Nmap sometimes apply based on these unofficial lists.

What Range This Port Belongs To

Port 2035 falls in the registered ports range (1024–49151).

This range was historically called "user ports" — ports above the privileged well-known range (0–1023) but below the ephemeral/dynamic range (49152–65535). Registered ports are intended for services that have applied to IANA for a formal assignment. Many are legitimately assigned; others, like 2035, remain open.

An unassigned registered port is not inherently suspicious. It simply means no service has claimed this number through IANA. Applications are free to use any unassigned port, and many do — for development servers, internal tools, custom protocols, and game servers.

How to Check What's Using Port 2035

If port 2035 is open or active on your system, you can identify what's using it:

On Linux or macOS:

# Show what process is listening on port 2035
sudo ss -tlnp | grep 2035

# Alternative using lsof
sudo lsof -i :2035

On Windows:

# Show listening ports with process IDs
netstat -ano | findstr :2035

# Match the PID to a process name
tasklist | findstr <PID>

With nmap (from another machine):

nmap -sV -p 2035 <target-ip>

The -sV flag tells nmap to probe the port and attempt to identify the service — which will tell you more than any database lookup will.

Why Unassigned Ports Matter

The port numbering system only works because most services agree to use their assigned numbers. Unassigned ports are the slack in that system — the open addresses that make it possible for new services to emerge without immediately colliding with something established.

Port 2035 is one of tens of thousands of unassigned registered ports. Collectively, they represent the Internet's available address space for services that haven't been invented yet, or haven't applied for a formal assignment, or exist only inside a single organization's network.

If you find port 2035 open in the wild during a scan, don't assume "imsldoc." Probe it. The only honest answer about what's running there is: whatever the person who set it up decided to run.