Mac OS X Network Discovery

Question

Simple question, what service/ports does Mac OS X Network Discovery used. Just NetBios?

Example: Go -> Network if connected you should see other devices on the network. Mac OS,Windows,etc.

From what I can tell its just NetBios. However, from Windows Explorer (Windows OS), I can only see Windows boxes which makes me wonder. (This is a theory NOT the ISSUE).

The issue in which is why I am trying to find out what Mac OS Network Discovery is used, is a Sonicwall UTM/Firewall issues.

One service is a SSL-VPN service. On subnets you can see the computers you normally do. No problem. The issue when connected to SSL-VPN client with NetBios enabled and IP Helper does not show devices in Mac OS --> Go -->Network. Doing a packet capture is not showing any drop packets.

This is why I am trying to figure out if Mac OS X Network Discovery uses something other then NetBios.

Thanks, Ben

Answer 1

macOS primarily uses Bonjour (mDNS, DNS-SD, IETF ZeroConf) for network service advertisement and discovery. So mainly ports 5353/UDP for multicast DNS and and 53/UDP for unicast DNS-SD (of course, unicast DNS can use 53/TCP as well). It also uses SMB browsing and name resolution mechanisms (NetBIOS, WINS) for finding SMB file servers, and for advertising its own SMB file services if SMB file sharing is enabled.