nerdexam
CompTIA

LX0-104 · Question #396

A user is attempting to connect to a remote server via SSH and receives the following message: The authenticity of host 'mail.example.com (208.77.188.166)' can't be established. RSA key fingerprint is

The correct answer is D. The server's SSH host key cannot be found in the list of known hosts.. This message indicates that the SSH client does not have a record of the remote server's host key in its known_hosts file, meaning it's the first time connecting or the server's key has changed.

Security

Question

A user is attempting to connect to a remote server via SSH and receives the following message: The authenticity of host 'mail.example.com (208.77.188.166)' can't be established. RSA key fingerprint is 92:32:55:e9:c4:20:ae:1b:2c:d7:91:40:90:89:1c:ad. Are you sure you want to continue connecting (yes/no)? What does this indicate?

Options

  • AThe RSA key fingerprint was found in the SpamCop database, indicating that the remote host is a
  • BThe user's SSH client was unable to connect to the remote host's authentication agent for verification.
  • CThe user's SSH client is incompatible with the server's RSA key.
  • DThe server's SSH host key cannot be found in the list of known hosts.

How the community answered

(34 responses)
  • A
    6% (2)
  • B
    3% (1)
  • C
    18% (6)
  • D
    74% (25)

Why each option

This message indicates that the SSH client does not have a record of the remote server's host key in its `known_hosts` file, meaning it's the first time connecting or the server's key has changed.

AThe RSA key fingerprint was found in the SpamCop database, indicating that the remote host is a

SSH host key fingerprints are not typically checked against spam databases; they are for cryptographic host identity verification.

BThe user's SSH client was unable to connect to the remote host's authentication agent for verification.

The message indicates a problem establishing the host's authenticity itself, not an inability to connect to an authentication agent (like `ssh-agent`).

CThe user's SSH client is incompatible with the server's RSA key.

The message provides the RSA key fingerprint, implying compatibility; incompatibility would usually result in a different error, like unsupported cipher or key type.

DThe server's SSH host key cannot be found in the list of known hosts.Correct

The message 'The authenticity of host 'mail.example.com (...) can't be established' specifically means that the SSH client has not previously recorded the public host key for the server it is attempting to connect to. This typically happens on the first connection to a new server, or if the server's host key has legitimately changed.

Concept tested: SSH host key verification and known_hosts

Source: https://man7.org/linux/man-pages/man1/ssh.1.html

Topics

#SSH#host key verification#known_hosts#security warning

Community Discussion

No community discussion yet for this question.

Sign up to join the discussion
Full LX0-104 Practice