Port 545 sits in the well-known port range—the first 1,024 ports reserved for standard Internet services. It was officially assigned to QuickTime Conferencing (also known as QTCP), Apple's video conferencing system from the mid-1990s.
The service is long dead. The port number remains.
What QuickTime Conferencing Was
In December 1995, Apple shipped the QuickTime Conferencing Kit for $289.1 This was the era of dial-up Internet, when video calling seemed like science fiction. The kit included a camera, microphone, and software that let two Macintosh users see and hear each other over a network connection.
QuickTime Conferencing used port 545 for its network protocol. The system was designed to work with H.320 standards-based videoconferencing systems—the expensive equipment used in corporate boardrooms—while also supporting Apple's proprietary protocol.2
It predated Skype by eight years. It predated FaceTime by fifteen.
Why This Port Exists
Port 545 is in the well-known port range (0-1023), which means it was assigned by the Internet Assigned Numbers Authority (IANA) for a specific, standardized service. Getting a well-known port number was significant—these assignments were meant to be permanent, global standards.
Apple got the assignment. The technology didn't last.
QuickTime Conferencing was discontinued as newer protocols emerged. Video calling eventually moved to different technologies: SIP, RTP, WebRTC. Port 545 became obsolete, but it remains officially assigned—reserved for a service that no longer exists.
What Happens to Deprecated Ports
Port 545 is marked as "deprecated" in IANA's registry. This means:
- The assignment still exists — The port number hasn't been reassigned to something else
- Nothing official uses it — Modern systems don't expect to find QuickTime Conferencing here
- It's effectively empty — Like a phone number that's been disconnected but not yet given to someone else
If you check what's listening on port 545 on your computer right now, you'll almost certainly find nothing:
Why Empty Ports Matter
The well-known port range is finite. There are exactly 1,024 positions, and they can't be expanded without breaking the fundamental design of TCP and UDP. Every port assigned to a dead protocol is a port that can't be used for something new.
Port 545 is one of many fossils in this range—numbers claimed by protocols from the 1980s and 1990s that no longer exist but haven't been formally reclaimed. IANA is conservative about reassigning deprecated ports because old systems might still expect them, even if no one actually uses them anymore.
So port 545 sits reserved. A tombstone in the well-known range. A reminder that the Internet still carries the names of services that vanished decades ago.
Security Note
Because port 545 has no active, legitimate use, anything listening on this port is suspicious. If you scan your network and find port 545 open, investigate immediately. It could be:
- Malware using an obscure port to avoid detection
- Misconfigured software accidentally binding to this port
- An extremely old system still running deprecated Apple software
None of these are good.
The Bigger Picture
Port 545 is part of the archaeology of the Internet. In 1995, when Apple claimed this port number, video conferencing seemed like it needed dedicated protocols and assigned port numbers. The assumption was that standard services would use standard ports forever.
That's not how it worked out. Modern video calling happens over HTTPS on port 443, using protocols that didn't exist when port 545 was assigned. The well-known port range is full of these stories—numbers that meant something once and now mean nothing.
Port 545 is a reservation for a future that never came.
Related Ports
- Port 554 — RTSP (Real Time Streaming Protocol), still used for streaming video
- Port 5060 — SIP (Session Initiation Protocol), used for VoIP and modern video calling
- Port 443 — HTTPS, where most modern video conferencing actually happens (Zoom, Google Meet, etc.)
Frequently Asked Questions About Port 545
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