Port 709 sits in the well-known range (0–1023), officially assigned to entrust-kmsh—the Entrust Key Management Service Handler. Both TCP and UDP versions exist, though you'll almost never see either in active use today.
What Is Entrust KMSH?
Entrust KMSH was a proprietary protocol for managing cryptographic keys in enterprise environments. In the 1990s and early 2000s, when organizations were building out public key infrastructure (PKI) systems, they needed ways to generate, distribute, store, and rotate encryption keys securely.1
Entrust, a network security company, built authentication and key management products that used port 709 for communication between key management services and clients.2 The protocol handled tasks like:
- Generating and distributing cryptographic keys
- Managing key lifecycles (creation, rotation, expiration)
- Providing secure key storage and retrieval
- Enabling centralized control over enterprise encryption
Why You Don't See It Anymore
Entrust KMSH was a proprietary solution. As the industry matured, organizations moved toward standardized protocols that worked across vendors and platforms. Today, the Key Management Interoperability Protocol (KMIP) is the dominant standard for cryptographic key management.3
Modern Entrust products use KMIP and other open standards rather than the legacy KMSH protocol. Port 709 remains assigned in IANA's registry, but the service it was designed for is essentially obsolete.
The Well-Known Range
Port 709 lives in the well-known ports range (0–1023), which means it was assigned by IANA for a specific, recognized service. In the early Internet, getting a well-known port number was significant—it meant your protocol was important enough to deserve a permanent address.
These ports were handed out more freely in the 1980s and 1990s than they are today. Many well-known ports, like 709, are assigned to services that never achieved widespread adoption or have since been replaced by newer standards.
Security Considerations
Port 709 appears in standard network scanning lists, which means security tools check for it when assessing network exposure.4 If you see port 709 open on a modern network, it's worth investigating:
- Is legacy Entrust software still running?
- Is something else using this port unofficially?
- Is it a misconfiguration or orphaned service?
The port itself isn't inherently dangerous, but any open port running outdated software is a potential risk.
Checking Port 709
To see if anything is listening on port 709:
On Linux or macOS:
On Windows:
If nothing returns, the port is closed. If something appears, you've found a service that's either running legacy Entrust software or repurposing the port for something else.
Why Unassigned (and Obsolete) Ports Matter
Ports like 709 tell the story of the Internet's evolution. Someone at Entrust needed a way for key management services to communicate. They requested a port number. IANA assigned 709. The protocol served its purpose for a time, then faded as better solutions emerged.
The port number remains assigned because IANA doesn't reclaim old allocations easily—doing so could break legacy systems that still depend on them, and it would create confusion in documentation and firewall rules that might still reference the port.
So port 709 sits in the registry, a marker of a protocol that mattered once and is now mostly forgotten. The Internet is full of these fossils—addresses reserved for services that barely anyone uses anymore, but that can't quite be erased.
Related Ports
Other ports in the PKI and key management space:
- Port 80/443 — HTTP/HTTPS, used by modern web-based key management interfaces
- Port 5696 — KMIP (Key Management Interoperability Protocol), the modern standard that replaced proprietary solutions like KMSH
Frequently Asked Questions About Port 709
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