XK0-005 Question #328: Real Exam Question with Answer & Explanation

Question

A security team informs the Linux administrator that a specific server is acting as an open relay. To which of the following is the security team referring?

Options

• AThe server is running the SSH service and is open to the Internet, allowing outside sources to log
• BThe server is acting as an unmanaged router, open to the Internet, and is allowing outside
• CThe server is acting as a web proxy and allowing outside unauthenticated sources to connect to
• DThe server has an email service configured to allow outside sources to send email to other

Explanation

An open relay refers to an email server configured to accept and forward email from unauthenticated external sources to any arbitrary destination on the Internet, often exploited for spam distribution.

Common mistakes.

• A. An SSH server open to the Internet is a security concern if not properly secured but does not define an 'open relay,' which specifically relates to email forwarding.
• B. A server acting as an unmanaged router allowing outside traffic defines a network routing issue, not an 'open relay,' which is specific to email.
• C. A web proxy allowing unauthenticated connections is a security risk but is distinct from an 'open relay,' which specifically applies to email services.

Concept tested. Email security, Open mail relay

Reference. https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/configure-smtp-server-prevent-open-relay

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