# NetBIOS and Samba Ports

Service Name Port Protocol
Name Resolution Service 137 UDP
Datagram Services (browsing) 138 UDP
Session Service 139 TCP
SMB 445 TCP Input, UDP Output

## Observations

These are the contents of /etc/services:

netbios-ns 137/udp   # NetBIOS Name Service
netbios-dgm 138/udp  # NetBIOS Datagram Service
netbios-ssn 139/tcp  # NetBIOS Session Service
microsoft-ds 445/tcp # Microsoft Directory Service


These are the ports that the Samba server listens on. A few things here:

1. The first three are ports ports used by Windows to ‘find’ other computers (a la “My Network”)
2. The last is for directory services
3. UDP 137 and 138 are serviced by nmbd
4. TCP 139 and 445 are serviced by smbd