Port 1635 sits in an interesting position: officially registered with IANA, assigned to a real company, but functionally invisible in practice.
What We Know
Port 1635 is registered in the IANA Service Name and Transport Protocol Port Number Registry as edb-server1 (EDB Server 1). The registration indicates it supports both TCP and UDP protocols.1
The "EDB" refers to EnterpriseDB (now known as EDB), a company that provides commercial PostgreSQL database products and services.2 EDB offers Postgres Advanced Server, replication tools, and various database management solutions.
What We Don't Know
Here's where it gets strange: despite being officially registered, there's virtually no public documentation about what edb-server1 actually does.
EDB's documentation extensively covers their products—Postgres Advanced Server (which typically runs on port 5444), EDB Replication Server, and various other tools—but port 1635 doesn't appear in their service port lists or configuration guides.3
It's a registered port with no visible service behind it.
The Registered Ports Range
Port 1635 belongs to the registered ports range (1024–49151). These ports are assigned by IANA upon application by a requesting entity. Unlike well-known ports (0–1023), which require privileged access to bind, registered ports can be used by regular user processes.
Getting a port registered means someone at EDB applied for it, explained what they planned to use it for, and received official assignment. But registration doesn't guarantee the port is actively used—it just means it's reserved.
Why Obscure Registered Ports Matter
The Internet has 65,535 ports per protocol. Only a fraction are actively used. Some ports, like 1635, are registered but rarely encountered. They exist in the registry as placeholders, reservations, or remnants of services that were planned but never widely deployed.
This matters because:
- Avoiding conflicts — Even if edb-server1 isn't widely used, no one else can officially claim port 1635
- Historical record — Port registrations document what companies were building, even if those services didn't survive
- Security scanning — Security tools flag unusual listening ports, and knowing 1635 is legitimately registered to EDB helps distinguish between authorized services and potential threats
Checking What's Using This Port
To see if anything is listening on port 1635 on your system:
Linux/macOS:
Windows:
If you find something listening here, it's likely an EDB product—or something pretending to be one.
The Mystery Remains
Port 1635 is a reminder that the IANA registry is part technical specification, part archaeology. Some ports carry well-known protocols that billions of devices use daily. Others, like this one, are officially assigned but functionally forgotten.
If you're running EDB software and see port 1635 in use, you're using a legitimate registered port. What's actually happening on that port? Even the Internet doesn't seem to remember.
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