What Port 486 Was
Port 486 was registered with the Internet Assigned Numbers Authority (IANA) for a protocol called "avian."1 Both TCP and UDP versions were assigned to Robert Ullmann, a network protocol engineer who contributed to early Internet architecture in the 1990s, including work on next-generation IP protocols and routing systems.2
The name "avian" strongly suggests a connection to RFC 1149, the famous April Fools' Day RFC titled "A Standard for the Transmission of IP Datagrams on Avian Carriers."3 That 1990 document humorously specified how to send Internet packets via carrier pigeon—complete with instructions for wrapping hex-encoded datagrams around bird legs with duct tape.
Port 486 appears to have been a formal port registration that referenced this joke. Someone thought the concept deserved its own port number. The Internet had a sense of humor, even in its official registries.
What Happened to It
On May 18, 2017, IANA removed port 486 from the official registry.4 The port is no longer assigned. No public documentation explains why it was removed, but deregistrations typically happen when a service is no longer in use, when the assignee requests removal, or when IANA cleans up historical entries that never saw real deployment.
There is no evidence that port 486 was ever used for actual network traffic. No implementations, no deployments, no packet captures showing "avian" protocol headers. It existed as a registry entry—a footnote, a wink—and then it was gone.
The Well-Known Ports Range
Port 486 sits in the well-known ports range (0-1023), which IANA reserves for system-level services.5 These ports typically require root or administrator privileges to bind on Unix-like systems. The well-known range is the most restricted and densely allocated portion of the port number space, and new assignments require IETF Review or IESG Approval.
That someone secured a well-known port number for an avian carrier protocol—even briefly—is remarkable. The bar for allocation in this range is high. Either this registration predates stricter allocation policies, or someone at IANA appreciated the reference enough to approve it.
IP Over Avian Carriers (The Joke That Worked)
RFC 1149, published April 1, 1990, specified how to transmit IP datagrams using homing pigeons.6 It included quality-of-service considerations like "storms can cause data loss" and "avian carriers can provide high delay, low throughput, and low altitude service."
In 2001, Bergen Linux User Group successfully implemented IPoAC, transmitting nine ping packets with a 55% packet loss rate and response times between 50 and 100 minutes.7 Over longer distances, pigeons carrying microSD cards can actually achieve higher bandwidth than some Internet connections—albeit with terrible latency.
The joke worked because it followed the RFC format precisely. It treated an absurd idea with engineering seriousness. Port 486 did the same thing—it made the joke official.
Checking What's on Port 486
Even though port 486 is deregistered, you can still check if anything is listening on it:
You will almost certainly find nothing. But if you do find something, it's either a misconfigured service, a custom application, or someone with an exceptional sense of humor running their own IPoAC implementation.
Why Unassigned Ports Matter
Most ports are unassigned. IANA maintains roughly 65,535 TCP ports and 65,535 UDP ports. Only a small fraction have official assignments. The rest form a vast commons where applications negotiate their own space.
Unassigned ports in the well-known range (like port 486 after its removal) can be used by anyone, but doing so risks collision with future official assignments. The registered ports range (1024-49151) is safer for custom services. The dynamic/ephemeral range (49152-65535) is used by operating systems for temporary outbound connections.
Port 486 moved from assigned to unassigned. It returned to the commons. If you need a port number for your carrier pigeon network, it's available again.
The Pattern
Port registrations tell stories. Some ports carry the entire Internet (port 443). Some carry niche protocols used by three people (port 387, AURP). Some exist as references to jokes, experiments, or ideas that never shipped.
Port 486 was assigned to "avian." It honored a protocol that transmitted packets at the speed of a pigeon's flight. Someone registered it, IANA approved it, and for years it sat in the official registry—a monument to the idea that the Internet should take itself seriously but not too seriously.
Then IANA removed it. The joke ended, or the joke was complete. Either way, port 486 is empty now.
If you see traffic on port 486, you're witnessing either an error or an homage. Both are worth investigating.
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