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XK0-005 · Question #302

Which of the following techniques would BEST allow a client computer to connect to a server that is not normally accessible because the server's application port is blocked by a firewall?

The correct answer is D. SSH port forwarding. When a server's application port is blocked by a firewall, SSH port forwarding is the best technique to establish a secure tunnel and bypass the restriction, allowing the client to connect to the inaccessible port.

Security

Question

Which of the following techniques would BEST allow a client computer to connect to a server that is not normally accessible because the server’s application port is blocked by a firewall?

Options

  • AX11 forwarding
  • BTCP wrappers
  • CRDP
  • DSSH port forwarding

How the community answered

(42 responses)
  • A
    2% (1)
  • B
    10% (4)
  • C
    7% (3)
  • D
    81% (34)

Why each option

When a server's application port is blocked by a firewall, SSH port forwarding is the best technique to establish a secure tunnel and bypass the restriction, allowing the client to connect to the inaccessible port.

AX11 forwarding

X11 forwarding is used to securely run graphical applications from a remote server on a local machine, not for bypassing blocked application ports for non-graphical services.

BTCP wrappers

TCP wrappers provide host-based network access control for services, preventing unauthorized access but not enabling connections to firewall-blocked ports.

CRDP

RDP (Remote Desktop Protocol) is a protocol for accessing a graphical desktop on a remote Windows machine, and it does not inherently bypass firewall restrictions on arbitrary application ports.

DSSH port forwardingCorrect

SSH port forwarding creates a secure tunnel through an SSH connection, allowing traffic intended for a blocked port on the target server to be redirected through an open SSH port. This technique effectively bypasses firewall restrictions on the application port by encapsulating the blocked traffic within the permitted SSH connection.

Concept tested: Bypassing firewall with SSH tunneling

Source: https://www.ssh.com/academy/ssh/tunneling/example

Topics

#SSH#Port Forwarding#Firewall#Network Access

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