Port 3283: Apple Remote Desktop
Port 3283 is used by Apple Remote Desktop for reporting and management of Macs.
What runs on port 3283
Apple Remote Desktop uses 3283 (the "Net Assistant" port) for collecting reports and managing Macs, and 5900 for screen control. It is turned on when you enable Remote Management in macOS sharing settings.
On a home network
Macs with Remote Management enabled listen on 3283. Most personal Macs have it off unless an employer or IT person turned it on.
If port 3283 is reachable from the internet
ARD should not be reachable from the internet. In 2019 attackers abused Macs exposing UDP 3283 as reflectors in DDoS amplification attacks. Exposed Remote Management also invites password guessing on the Mac itself.
How to check whether it is open on your network
On a Mac, open System Settings, General, Sharing and check whether Remote Management is on. Confirm no router rule forwards 3283 or 5900.
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