Port 690: VATP — The officially well-known port almost nobody knows

Port 690 carries VATP (Velneo Application Transfer Protocol), a proprietary protocol for the Velneo development platform. It has an official IANA reservation in the well-known ports range—the same prestigious tier as HTTP (80) and HTTPS (443)—yet most people have never encountered it.¹

This is the strange reality of port assignments: official status doesn't guarantee widespread use.

What is VATP?

VATP is an application layer protocol that allows components of the Velneo platform to exchange information. Velneo is a low-code development environment for building business applications, primarily popular in Spanish-speaking markets.

The protocol uses both TCP and UDP on port 690:²

TCP/690 handles application transfers and data synchronization. The connection-oriented nature of TCP ensures reliable delivery of application packages and related data between Velneo servers and clients.

UDP/690 carries lightweight communication and status updates. The connectionless nature of UDP allows faster transmission for real-time monitoring and reporting.

VATP is optimized to work across different network conditions—whether you're on a fast local LAN or a slow Internet connection, the protocol adapts.

The well-known ports range

Port 690 sits in the well-known ports range (0-1023). These ports are supposed to be reserved for fundamental Internet services. Getting a port number in this range requires IANA approval—it's the most privileged tier of port assignments.

And yet, port 690 carries a protocol that most network administrators will never see on their systems.

This isn't a criticism of VATP or Velneo. It's an observation about how port assignments work: once IANA grants a number, it stays assigned regardless of how widely the protocol is actually deployed. Port 690 is officially well-known, even if it's practically unknown.

Other reported uses

Some sources mention port 690 being used by:³

• Microsoft SharePoint Server 2010 User Profile Synchronization Service
• Mac OS X RPC-based services for NetInfo

These appear to be unofficial uses—applications that happened to choose port 690 without formal assignment. This creates potential conflicts if both VATP and SharePoint try to use the same port on the same system.

Checking what's listening on port 690

If you see port 690 listening on your system, you should verify what's using it:

On Linux/macOS:

sudo lsof -i :690
sudo netstat -tulnp | grep 690

On Windows:

netstat -ano | findstr :690

The process name will tell you what's actually running—whether it's Velneo vServer, SharePoint, or something unexpected.

If you find port 690 listening and you're not running Velneo or SharePoint, investigate. Unexpected open ports can indicate intrusion or misconfiguration.⁴

Why this matters

Port 690 demonstrates something important about Internet infrastructure: official doesn't mean universal.

The well-known ports range was designed for protocols that everyone needs—HTTP, DNS, SSH, SMTP. But it also contains dozens of protocols that serve specific industries or platforms. Port 690 is perfectly legitimate, properly assigned, and completely unknown to most of the Internet.

This is fine. Not every protocol needs to be universal. But it means you can't assume a port number tells you how important or widespread a service is. Port 690 has the same official status as port 80, even though the traffic they carry operates at completely different scales.