Port 845 is unassigned—it has no official service, no RFC defining its purpose, no protocol claiming it as home.
What Range This Port Belongs To
Port 845 falls within the well-known ports range (0-1023). These ports are controlled by the Internet Assigned Numbers Authority (IANA), which assigns them to standardized services and protocols.1
Getting a well-known port assigned requires convincing IANA that your protocol is important enough to deserve one of these low numbers. Most of them are already taken—HTTP got 80, HTTPS got 443, SSH got 22. The well-known range is valuable real estate.
Port 845 sits in that range but remains empty. It's been reserved for decades without ever being claimed.
Why Unassigned Ports Matter
The existence of unassigned ports is actually important to how the Internet works.
Room for future protocols — New services occasionally need well-known ports. Having unassigned numbers means IANA can allocate them when genuinely important protocols emerge.
Clear boundaries — An unassigned port should have nothing listening on it by default. If you scan your system and find something on port 845, that's worth investigating—it's either a custom service you configured, or something that shouldn't be there.
Flexibility for testing — Developers sometimes use unassigned ports for testing new protocols or experimental services without conflicting with existing assignments.
What You Might Find on Port 845
While IANA hasn't assigned port 845 officially, you might occasionally find something listening there:
- Custom applications — Developers sometimes pick random unassigned ports for private services
- Misconfigurations — Software configured to use the wrong port number
- Port scanning artifacts — Security scanners checking what's listening
If you find port 845 open on a system you're responsible for, it's worth checking what put it there. Unassigned doesn't mean "safe to ignore"—it means "shouldn't be here unless you know why."
How to Check What's Listening
On Linux or macOS:
On Windows:
If something is listening, these commands will show you which process opened the port. You can then decide whether it belongs there.
The Well-Known Ports Range
Port 845 is one of 1,024 ports in the well-known range. IANA maintains this registry, and getting a port assigned involves:
- Submitting a formal request with protocol documentation
- Demonstrating that the service is standardized and widely needed
- Waiting for IANA review and approval
Most requests are for the registered ports range (1024-49151) instead, which has looser requirements. The well-known range is increasingly crowded, and IANA is conservative about new assignments.2
Port 845 has survived this long without being claimed, which means no protocol has made a compelling enough case to take it.
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