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SK0-004 · Question #116

A server technician needs to access a remote Unix server for administration. The technician has requested that ports 23, 25, and 161 be opened on the router. After the ports are opened, the…

The correct answer is B. TCP 22. SSH (TCP 22) is the standard protocol for secure remote administration of Unix/Linux servers, and it was not included in the ports the technician requested.

Troubleshooting

Question

A server technician needs to access a remote Unix server for administration. The technician has requested that ports 23, 25, and 161 be opened on the router. After the ports are opened, the technician is still unable to connect to the Unix server. Which of the following ports should be opened on the server to allow for remote administration?

Options

  • ATCP 21
  • BTCP 22
  • CUDP 69
  • DTCP 3389

How the community answered

(46 responses)
  • A
    4% (2)
  • B
    76% (35)
  • C
    7% (3)
  • D
    13% (6)

Why each option

SSH (TCP 22) is the standard protocol for secure remote administration of Unix/Linux servers, and it was not included in the ports the technician requested.

ATCP 21

TCP 21 is used by FTP for file transfers and does not provide remote shell administration capability.

BTCP 22Correct

SSH (Secure Shell) operates on TCP port 22 and is the standard protocol for encrypted remote command-line administration of Unix and Linux systems. The technician opened ports 23 (Telnet), 25 (SMTP), and 161 (SNMP), none of which provide interactive remote shell access. Without TCP 22 open, SSH connections to the Unix server will be blocked.

CUDP 69

UDP 69 is used by TFTP for simple file transfers and does not enable remote administration sessions.

DTCP 3389

TCP 3389 is used by RDP (Remote Desktop Protocol) for graphical remote access to Windows systems, not Unix servers.

Concept tested: SSH port 22 for Unix remote administration

Source: https://www.openssh.com/manual.html

Topics

#SSH#remote administration#port 22#Unix server access

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