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LFCS · Question #317

Which of the following ports are used by smbd? (Choose THREE correct answers)

The correct answer is A. 135/TCP D. 139/TCP E. 445/TCP. The smbd daemon primarily uses TCP ports 139 and 445 for SMB/CIFS communication, and also 135/TCP for MSRPC when acting as a domain controller.

Submitted by zhang_li· Apr 18, 2026Networking

Question

Which of the following ports are used by smbd? (Choose THREE correct answers)

Options

  • A135/TCP
  • B137/UDP
  • C138/UDP
  • D139/TCP
  • E445/TCP

How the community answered

(26 responses)
  • A
    92% (24)
  • B
    4% (1)
  • C
    4% (1)

Why each option

The `smbd` daemon primarily uses TCP ports 139 and 445 for SMB/CIFS communication, and also 135/TCP for MSRPC when acting as a domain controller.

A135/TCPCorrect

Port 135/TCP is used for Microsoft Remote Procedure Call (MSRPC) services, which Samba's `smbd` can utilize, particularly when functioning as a domain controller or providing specific RPC-dependent services.

B137/UDP

Port 137/UDP is used by the `nmbd` daemon for NetBIOS Name Service (NBNS), not by `smbd` for SMB/CIFS connections.

C138/UDP

Port 138/UDP is used by the `nmbd` daemon for NetBIOS Datagram Service, not by `smbd` for SMB/CIFS connections.

D139/TCPCorrect

Port 139/TCP is traditionally used by `smbd` for SMB/CIFS communication over NetBIOS sessions, enabling file and printer sharing for clients that rely on this protocol.

E445/TCPCorrect

Port 445/TCP is the modern standard for direct SMB/CIFS communication over TCP/IP, and it is actively used by `smbd` for file and printer sharing services without the need for NetBIOS.

Concept tested: Samba smbd daemon ports

Source: https://www.samba.org/samba/docs/current/manpages/samba.7.html

Topics

#Samba#Networking Ports#SMB/CIFS#Service Daemons

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