Port 643 lives in the well-known ports range (0-1023), officially registered with IANA for a service called SANity—a storage area network (SAN) management protocol.1 Despite this official status, you're unlikely to ever see it in use.
This is the reality of the port number system: thousands of assignments, many serving highly specialized purposes or representing protocols that never gained widespread adoption.
What SANity Does
SANity is registered for storage area network management and monitoring.2 Storage area networks are specialized high-speed networks that connect storage devices to servers, commonly found in enterprise data centers and large-scale computing environments.
The protocol runs on both TCP and UDP port 643, though public documentation about its actual operation is scarce. This isn't unusual—many enterprise storage protocols are proprietary or used only within specific vendor ecosystems.
The Well-Known Ports Range
Port 643 sits in the well-known ports range (0-1023), which is managed directly by IANA. These ports are meant for system-level services and standardized protocols. Getting a port assigned in this range requires official registration through IANA.
The assignment was made to Peter Viscarola, a Windows driver architect and storage systems expert.3 This suggests SANity was likely developed for Windows-based storage environments.
Why You Won't See It
Despite being officially registered, SANity appears to be either:
- A proprietary protocol used only within specific enterprise environments
- A protocol that never gained widespread adoption
- A legacy assignment for software that's no longer actively developed
This is common in the port registry. Many assignments were made years ago for products or protocols that served specific needs at the time but never became widely deployed.
Checking What's Actually There
If you want to see what's listening on port 643 on your system (most likely nothing):
Linux/macOS:
Windows:
If something is listening on port 643, it's worth investigating—it could be legitimate SAN management software, or it could be something unexpected.
Security Considerations
Port 643 has been associated with malicious activity in the past—some malware has used this port for command and control communications.4 This is precisely because obscure, rarely-used ports make good hiding spots for unauthorized traffic.
If you're not running SAN management software and you see activity on port 643, investigate it. Unexpected traffic on specialized ports is often a red flag.
Related Ports
Other ports in the storage and network management space:
- Port 3260 - iSCSI (Internet Small Computer Systems Interface), widely used for SAN access over IP networks
- Port 2049 - NFS (Network File System), for sharing files over networks
- Port 161/162 - SNMP (Simple Network Management Protocol), commonly used for monitoring network and storage devices
The Port Registry Reality
Port 643 represents something important about how the Internet's numbering system works: official assignment doesn't guarantee actual usage.
IANA maintains assignments for over 50,000 port numbers. Many are actively used by protocols you depend on every day. Many more are like port 643—officially registered, technically valid, but practically invisible. They're there if needed, sitting quietly in the registry, waiting for traffic that may never come.
This isn't waste or inefficiency. It's the nature of maintaining a global namespace. Better to have the assignment and not need it than to need it and have to fight over port numbers.
Frequently Asked Questions About Port 643
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