Port 3679: Newton Dock — A fossil in the registry

What This Port Does

Port 3679 is registered to Newton Dock, the TCP protocol Apple used to synchronize Newton PDA devices with desktop computers in the 1990s.

When a Newton MessagePad or eMate connected over a network, it opened a TCP session on port 3679 to talk to Newton Connection Utilities on the host machine. Through that connection you could back up notes, sync calendar entries, install packages, and even use your Mac's keyboard to type on the Newton's screen.¹

The Newton was discontinued in 1998. Port 3679 was not.

The Range It Lives In

Port 3679 sits in the registered port range (1024-49151). This is the middle tier of the port system:

• Well-known ports (0-1023): Reserved for foundational protocols like HTTP (80), HTTPS (443), and SSH (22). Requires root/administrator privileges to open a listener.
• Registered ports (1024-49151): Assigned by IANA to specific services and applications. Anyone can open a listener on these without special privileges, but IANA tracks who has a claim.
• Dynamic/ephemeral ports (49152-65535): Unmanaged. Used temporarily by operating systems for outbound connections.

Registered ports are supposed to mean something. IANA maintains the registry so that two applications don't accidentally collide on the same port number. Port 3679's registration is legitimate — Apple requested it, IANA assigned it, and the assignment still stands today.²

The Newton Dock Protocol

The Newton Dock protocol handled communication between Newton OS 2.x devices (MessagePad 130, 2000, 2100, and the eMate 300) and host computers. It ran over both TCP/IP and serial connections.

The TCP variant is what used port 3679. A Newton on a local network would initiate a connection to the host, and the Dock protocol would take over from there — a structured handshake followed by commands for backup, sync, and package installation.¹

By modern standards the protocol is simple. By 1990s standards it was sophisticated: a handheld device syncing wirelessly over TCP years before Palm had figured out the same problem.

Still in Use

The Newton has a small but committed following. Open-source projects continue to implement the Dock protocol on port 3679:

• NewtonKit is a Swift implementation of the Newton Dock protocol, actively maintained, that starts a TCP server on port 3679 to connect to real Newton hardware or the Einstein emulator.¹
• NCX (Newton Connection for Mac) uses the same protocol and port to back up and sync Newton devices today.³

These are not abandonware projects running on ancient systems. They are maintained codebases, running on current macOS, connecting to devices that stopped shipping when the iMac G3 was new.

How to Check What's Listening on This Port

If you want to see whether anything is using port 3679 on your machine:

macOS / Linux:

# Check if anything is listening on port 3679
lsof -i :3679

# Or with netstat
netstat -an | grep 3679

# Or with ss (Linux)
ss -tlnp | grep 3679

Windows:

netstat -ano | findstr :3679

If you see a process listening here and you're not running Newton sync software, it's worth investigating. Unexpected listeners on registered ports are worth a second look.

Why Unassigned (and Registered) Ports Matter

The port registry exists to prevent chaos. Without it, applications would constantly step on each other — your database and your messaging app both trying to claim port 5432, neither one winning cleanly.

Port 3679's continued registration for Newton Dock illustrates both the value and the quirk of the system. The assignment is accurate. The service is real. The hardware is in museums. The port stays reserved because IANA doesn't reclaim registrations when products are discontinued.

This is probably correct behavior. Someone might still be running Newton connection software. The reservation costs nothing. The collision it prevents — some future application accidentally claiming the Newton's port — is real.