What Port 1697 Is
Port 1697 sits in the registered ports range (1024–49151). These ports are not reserved by the operating system the way well-known ports (0–1023) are — any process can bind to them without special privileges. They are, however, tracked by IANA, which maintains a registry of names and assignments to prevent collisions.
Port 1697 is assigned to a service called rrisat, registered for both TCP and UDP.1
The Problem: Nobody Documented It
The IANA entry for port 1697 contains a name, a protocol, and a contact: Allen Briggs at briggs@access.rrinc.com. That is the complete extent of public knowledge.
There is no RFC. No specification. No archived documentation explaining what "rrisat" stands for, what problem it solved, or who was meant to use it. The domain rrinc.com no longer exists. The registration appears to date from the 1990s, when IANA port assignments were informal — you emailed a request, you got a number, you may or may not have written anything down.
"rrisat" may stand for something related to RR Inc, whatever that company did. It may have been an internal service that was registered prophylactically and never deployed publicly. The honest answer is: we don't know.
What This Port Is Used for Today
Nothing documented. Port databases show the IANA name and nothing else.2 There are no known malware associations, no observed traffic patterns, no community reports of software using this port in the wild.
If you see traffic on port 1697, it is almost certainly something specific to your environment — a custom application, a development service, or a misconfigured tool — rather than any standardized protocol.
How to Check What's Listening on Port 1697
If you want to see whether anything on your machine is using this port:
On Linux or macOS:
On Windows:
These commands show the process ID bound to the port, which you can then look up to identify the application.
Why Ports Like This Exist
The registered port range has over 48,000 slots. Thousands of them look like this: a name, a number, a contact from a company that dissolved years ago, and no surviving documentation. IANA's registry is a historical record as much as a technical one — it captures the moment someone cared enough to claim a number, without guaranteeing they ever explained why.
This is not a flaw. Unassigned and ghost-assigned ports form the open ocean of the port space, available for applications to use without fear of colliding with something standardized. When you run a development server on a random high port, you are swimming in this ocean.
Port 1697 is a ghost — registered, named, and forgotten.
Frequently Asked Questions
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