Port 258 sits in the well-known ports range (0-1023) but carries no official service assignment. IANA marked it "Unassigned" in 2006, and it has remained that way since.1
But unassigned doesn't mean empty.
What Well-Known Means
Ports 0-1023 are called "well-known ports" or "system ports." They're assigned by IANA to standardized services. On most operating systems, binding to these ports requires privileged access—you need root or administrator rights.
Port 258 falls in this range. It sits between port 257 (assigned to Secure Electronic Transaction) and port 259 (assigned to Efficient Short Remote Operations). The gap is intentional space in the registry.
Unofficial Uses
Despite having no official assignment, port 258 has been observed in the wild for two distinct purposes:
Check Point FireWall-1: The fwpolicy service, part of Check Point's FireWall-1/VPN-1 security software, has historically used TCP port 258 for remote policy management. The firewall management console listens on this port to receive policy updates.2
Malware Communication: Security researchers have flagged port 258 as a vector for trojan and virus communication. While this doesn't mean current malware necessarily uses it, the port has appeared in historical malware analyses.3
This is the reality of unassigned ports: they become useful to whoever needs them, whether that's legitimate software or malicious code.
Why Unassigned Ports Matter
The Internet's port system has 65,535 possible port numbers. Only a fraction are officially assigned. The rest—the unassigned ports, the registered ports without formal services, the ephemeral ports that change with every connection—form the flexible space where new protocols emerge and applications find room to operate.
Unassigned doesn't mean protected. It means available. Anyone can use an unassigned port for anything. Without an official service definition, there's no standard behavior, no expected protocol, no assumption of safety.
This makes unassigned ports both useful and dangerous. Useful because developers can experiment without conflicts. Dangerous because malware can operate without detection.
Checking What's Listening
To see if anything is using port 258 on your system:
Linux/macOS:
Windows:
If something is listening on port 258, you'll need to investigate what it is. It could be legitimate software (like Check Point FireWall-1), or it could be something else.
The Space Between
Port 258 represents the gaps in the official Internet. The registry is not complete, not fully populated, not entirely claimed. These gaps are where innovation happens and where threats hide.
The port carries no standard. That's both its freedom and its risk.
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