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CompTIA A+ Core 1 (220-1201)NetworkingMedium

A technician wants to remotely administer a Linux server's command-line interface over an encrypted connection. Which of the following ports should the technician ensure is open on the firewall?

  1. A22
  2. B3389
  3. C23
  4. D20
Show answer & explanation

Correct answer: A. 22

SSH (Secure Shell) uses TCP port 22 and provides an encrypted command-line connection, making it ideal for securely administering a Linux server. Port 23 is Telnet, which is unencrypted; port 20 is FTP data; and port 3389 is RDP, used for Windows graphical remote desktop.

Why the other options are wrong

  • B. RDP uses port 3389 and is primarily used for Windows GUI remote access.
  • C. Telnet uses port 23 but transmits data unencrypted.
  • D. Port 20 is used for FTP data transfer, not remote administration.

SSH Port 22

SSH (Secure Shell) provides an encrypted method for remotely accessing a command-line interface, using TCP port 22.

  • Default port: TCP 22
  • Replaces insecure Telnet (port 23)
  • Commonly used to manage Linux/Unix servers

Memory trick: SSH is Telnet's secure sibling — 22 not 23.

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