Port 463 sits in the well-known port range (0-1023) with an official IANA assignment to a service called "alpes." That's where the story ends. Or rather, that's where the documentation ends.
What Is Port 463?
According to the IANA Service Name and Transport Protocol Port Number Registry, port 463 is assigned to "alpes" for both TCP and UDP protocols. The registry lists a contact person but provides no description, no RFC, no documentation about what the protocol does or did.
Unlike SNPP (Simple Network Paging Protocol), which uses port 444 and has clear documentation in RFC 1568, port 463's "alpes" service has no corresponding technical specification that's publicly available or widely known.
The Well-Known Port Range
Port 463 belongs to the System Ports range (0-1023), also called well-known ports. This range is reserved for services assigned by IANA through formal processes like IETF Review or IESG Approval. These are the ports that shaped the Internet—FTP on 21, SSH on 22, HTTP on 80, HTTPS on 443.
Port 463 has the same official status as those foundational services. But unlike them, nobody seems to remember what it's for.
What the Data Shows
The SANS Internet Storm Center tracks scanning activity on port 463. The data shows that port 463 does get scanned—IP addresses probe it looking for running services, potential vulnerabilities, or open doors. But the scanning data doesn't tell us what legitimate service, if any, ever ran here.
Checking Port 463 on Your System
To see if anything is listening on port 463:
On Linux or macOS:
On Windows:
If you find something listening on port 463, you've discovered something genuinely unusual. Document it. It might be the only evidence left of what "alpes" actually was.
Why Unassigned and Forgotten Ports Matter
Not every port tells a grand story. Some ports are registered and forgotten. Some never get used. Some represent protocols that solved problems we don't have anymore, built by people who moved on to other things.
Port 463 is a reminder that the Internet's infrastructure isn't all heroic protocols and elegant standards. Some of it is just bureaucracy—assignments made, names recorded, purposes lost.
The registry preserves the name "alpes" the same way an archaeologist preserves a fragment of pottery. We know it existed. We know someone made it. We don't know what it was for.
Security Considerations
Even though the "alpes" protocol is undocumented, port 463 remains in the well-known range. If you're running a firewall:
- Block port 463 unless you specifically know you need it (you almost certainly don't)
- Monitor for unexpected traffic on this port—it could indicate scanning or exploitation attempts
- Don't run unknown services on well-known ports without understanding what you're doing
Related Ports
- Port 444 — SNPP (Simple Network Paging Protocol), sometimes confused with port 463
- Port 462 — Unassigned
- Port 464 — kpasswd (Kerberos password changing protocol)
Frequently Asked Questions
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