What Port 2020 Is
Port 2020 sits in the registered port range (1024–49151). These ports are assigned by IANA to specific services, distinguishing them from the well-known ports (0–1023) reserved for foundational protocols like HTTP, SSH, and DNS.
The IANA registry lists port 2020 as assigned to a service called xinupageserver on both TCP and UDP.1 That's where the trail goes cold.
The Official Tenant Nobody Knows
"Xinupageserver" appears in the IANA registry with an assignment, a name, and almost nothing else. There is no RFC. There is no public documentation. There is no company proudly claiming it. The service exists in the registry the way a name might exist in a phone book for a number that was disconnected decades ago.
This happens. The registered port range has thousands of entries, many assigned to products that were once specific to a company or project and have since been abandoned, renamed, or quietly forgotten. The IANA registration is permanent; the service is not.
What Actually Uses Port 2020
In the absence of its official tenant, port 2020 has attracted squatters:
VMware vCenter uses port 2020 internally for certain operations — a common pattern where enterprise software picks ports without regard for IANA assignments.2
Malware has claimed it more than once. Backdoor.Rockse, a remote access trojan for Windows, opens a server on port 2020 (or 2525).2 WinRemoteShell (also called Onalf) listens on TCP 2020 and, notably, requires no password — anyone can connect.2 An IBM Tivoli Provisioning Manager vulnerability (CVE-2010-4121) involved an authentication bypass on this port.2
This is not unusual for ports with dormant official assignments. Malware authors often pick ports that firewalls are unlikely to block specifically because the port lacks a well-known, actively defended service.
What "Registered" Actually Means
The registered range exists so that applications can request a consistent port number, reducing the chance of conflict. But IANA registration is not enforcement. Any application can open any port. The registry is a coordination mechanism, not access control.
An assigned port with an absent tenant is, in practice, unclaimed territory.
How to Check What's Listening on This Port
If you see traffic on port 2020 and want to know what's using it:
On Linux/macOS:
On Windows:
The process ID in the output can be cross-referenced against Task Manager or tasklist to identify the application.
If you find something listening on 2020 that you didn't put there, investigate. Given the malware associations, unexpected activity on this port warrants scrutiny.
Frequently Asked Questions
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