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CompTIA

XK0-006 · Question #76

An administrator has generated an RSA SSH key pair to log in to a remote server. After copying the public key and attempting to log in, the administrator sees the following message…

The correct answer is B. Create a new key pair by running ssh-keygen -t ecdsa. The “no mutual signature algorithm” error means the RSA/SHA-1 key type (ssh-rsa) isn’t supported by both client and server. Generating a new key with a modern algorithm (e.g., ssh- keygen -t ecdsa) ensures a mutually supported signature method.

Troubleshooting

Question

An administrator has generated an RSA SSH key pair to log in to a remote server. After copying the public key and attempting to log in, the administrator sees the following message:

[email protected]: Permission denied (publickey,password) After seeing the message, the administrator attempts to connect using ssh -v [email protected] and notices the following debug output:

debug1: send_pubkey_test: no mutual signature algorithm Which of the following actions should the administrator take first to remediate this issue?

Options

  • AIssue systemctl restart sshd on the local server.
  • BCreate a new key pair by running ssh-keygen -t ecdsa.
  • CSet PermitRootLogin yes in the /etc/ssh/sshd_config file.
  • DUpdate permissions on the /home/admin/.ssh directory to 700 on the remote server.

How the community answered

(56 responses)
  • A
    9% (5)
  • B
    64% (36)
  • C
    23% (13)
  • D
    4% (2)

Explanation

The “no mutual signature algorithm” error means the RSA/SHA-1 key type (ssh-rsa) isn’t supported by both client and server. Generating a new key with a modern algorithm (e.g., ssh- keygen -t ecdsa) ensures a mutually supported signature method.

Topics

#SSH key pair#ECDSA#mutual signature algorithm#RSA compatibility

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