I have been researching this for a bit, but I have been getting conflicting answers, does samba, from my gatherings, SMB runs on ports TCP & UDP 137-139 & 445. But I have no idea therefore whether TCP or UDP is being used for File transfer. I think I have come to understand that 137-139 is for Name resolution, but the rest is a mystery still. I want to ensure the files I am going to be transferring are bit for bit accurate, thus looking for connection oriented TCP. I was hoping some more experienced administrators could give me a bit of help!

Thanks, -Eric


This is what I came up with


 Service                   | Pro   | Port  | Desription                
 NetBIOS Name Resolution   | UDP   |   137 |   Resolves into unique, flat 16 character name
 NetBIOS Datagrams         | UDP   |   138 |   Ability to send text message across NetBIOS `net send`
 NetBIOS Session           | TCP   |   139 |   Session data, such as negotiation of the SMB connection is exchanged, actual SMB connection is not here. Keepalives sent to ensure Session is still valid
 SMB                       | TCP   |   445 |   Data exchanged, files, printer, etc.

NOTE: NetBIOS can be disabled and DNS can be used instead, see: NetBIOS on technet

NOTE: See Disabling NetBIOS in wWindows


For a regular member server, see:


For a server acting as an AD domain controller, see:


  • That says what I knew, as far as port usage; but not whether the files themselves run over 445/tcp or I could also them falling under the description of datagram or session. – ehiller Sep 13 '15 at 4:34
  • Have you googled the service names themselves? Hint: Pay particular attention to "NetBIOS Session" and "SMB over TCP" – Brandon Xavier Sep 13 '15 at 14:27

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