Port 310 is officially assigned by IANA to a service called bhmds. Both TCP and UDP. Registered by John Kelly at bellhow.com sometime in the early days of the Internet.
And that's basically all anyone knows.
What We Know
Port 310 sits in the well-known port range (0-1023), which means at some point, someone convinced IANA that bhmds was important enough to deserve a permanent spot in the registry.1 Well-known ports are supposed to be for fundamental Internet services—things like HTTP (80), SMTP (25), DNS (53). Getting one assigned meant your protocol mattered.
But bhmds left no trace. No RFC. No documentation. No clear description of what it did or why it existed. The assignment is real—it shows up in the official IANA registry2—but the service itself has vanished.
The System Port Range
Port 310 belongs to the System Ports range (0-1023), also called well-known ports. These are assigned by IANA through the "IETF Review" or "IESG Approval" procedures, which means they're supposed to be for standardized protocols that serve a clear Internet-wide purpose.3
Ports in this range are privileged on Unix-like systems—you need root access to bind to them. This restriction exists because these ports are meant for system services, not random applications.
What Happened to bhmds?
Nobody knows. The service name exists. The port assignment is official. But whatever bhmds was supposed to do has been forgotten. The company (bellhow.com) is long gone. The contact (John Kelly) left no public record of what the service did.
This happens more often than you'd think. The early Internet moved fast. Companies registered port numbers for protocols they were building. Some of those protocols took off. Many didn't. The port assignments remain, like archaeological artifacts with no context.
Security Note
Port 310 has been flagged in the past by security databases because malware has occasionally used it for command and control communication.4 This doesn't mean bhmds itself was malicious—it means that once a port is abandoned, anyone can use it. Malware authors sometimes pick obscure assigned ports specifically because they're less likely to be monitored than completely random high ports.
If you see unexpected traffic on port 310, investigate it. The legitimate bhmds service is almost certainly not running.
How to Check What's Listening on Port 310
On Linux or macOS:
On Windows:
If something is listening on port 310, it's either legacy software, a research project, or something you should probably investigate.
Why Unassigned and Forgotten Ports Matter
Port 310 is a reminder that the Internet's infrastructure isn't just technical—it's human. Protocols are built by people trying to solve specific problems. Sometimes those problems get solved. Sometimes the company goes out of business. Sometimes the protocol never gets finished.
But the port assignment remains, a permanent marker of something that once mattered enough to claim a spot in the registry, even if no one remembers why.
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