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Difficulty: HardNetworking Ports and Protocols

A system administrator is configuring network firewall rules for a newly installed Network-Attached Storage (NAS) device. The NAS will serve files to Windows workstations using direct SMB communication over TCP/IP without relying on legacy NetBIOS resolution. Which of the following port rules must be permitted outbound and inbound on the firewall to enable native file sharing?

  1. TCP 445Answer
  2. B
    TCP 139
  3. C
    TCP 389
  4. D
    UDP 67

Answer

Allowing TCP port 445 enables direct SMB file sharing over IP without requiring legacy NetBIOS transport services.
Direct hosting of Server Message Block (SMB) over TCP/IP bypasses the NetBIOS transport layer entirely and communicates strictly on TCP port 445. Opening TCP port 445 on the firewall allows client computers to establish direct file-sharing sessions with the Network-Attached Storage appliance.

Step-by-Step Solution

1
Identify the primary service requested
The scenario describes Server Message Block (SMB) file sharing over TCP/IP.
The system administrator needs to open the specific port dedicated to native SMB communications.
2
Differentiate native SMB from legacy SMB over NetBIOS
Modern SMB operating directly over TCP/IP uses TCP port 445, whereas legacy SMB over NetBIOS relies on TCP port 139 alongside UDP ports 137/138.
The requirement specifies operating without legacy NetBIOS resolution.
3
Select the exact port rule required for the firewall configuration
TCP port 445 is the correct protocol port to permit.
Opening TCP port 445 satisfies native SMB file transfer requirements while maintaining minimal port exposure.

Key Concept

Server Message Block (SMB) Port Assignment
Estimated Time:1m 30s
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Topics

Networking Ports and Protocols

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