No. netbiosd talks only on your local network, for Windows-style file sharing discovery.
It lets your Mac find and be found by Windows file-sharing devices (SMB) by name on the local network. It runs as the _netbios user.
NetBIOS is a decades-old Windows protocol for naming computers on a LAN; macOS still speaks it so Windows PCs and NAS devices appear in Finder's Network sidebar. Its traffic is broadcasts on UDP 137 and 138 within your network, never to the internet. On networks with many Windows devices, it can move a surprising amount of small packets.
Facts
- Owner
- Apple (part of macOS)
- Network-related
- Yes
- Typical ports
- 137, 138
- Block it?
- It depends
What it connects to
| Host | Country | Purpose |
|---|---|---|
| Local network broadcasts (UDP 137, 138) | LAN | Windows/SMB name discovery |
Should you worry?
No. netbiosd talks only on your local network, for Windows-style file sharing discovery. You can leave it alone; if you never use SMB file sharing with Windows devices, its traffic is just background chatter.
Frequently asked questions
What is netbiosd?
The macOS NetBIOS name service, used to discover and name Windows file-sharing (SMB) devices on your local network.
Why is netbiosd using the network?
It listens for and answers NetBIOS name broadcasts on your LAN. The traffic stays on your local network.
Can I disable netbiosd?
It's managed by macOS. If you don't share files with Windows devices, its traffic is harmless background chatter.