300-410 Question 248
Single answerA network administrator is configuring secure remote access to a Cisco router using VTY lines. They want to ensure that only SSH connections are allowed, and Telnet access is disabled. Which command sequence should the administrator use to achieve this?
- A
line vty 0 4 transport input none
- B
line vty 0 4 transport input ssh
- C
line vty 0 4 transport input ssh telnet
- D
line vty 0 4 transport input all
Show answer and explanation
Correct answer: B
Explanation
To ensure secure remote access to the router using VTY lines, SSH should be the only protocol allowed. The command 'transport input ssh' under the VTY configuration achieves this by explicitly enabling SSH while disabling all other protocols, including Telnet. Other options either disable all access or allow insecure protocols like Telnet, which do not meet the stated requirement.
- A. Incorrect.
This option disables all access to the VTY lines, including SSH and Telnet, which is not the requirement.
- B. Correct.
This option configures the VTY lines to accept only SSH connections, which meets the requirement to allow only secure access via SSH and disable Telnet.
- C. Incorrect.
This option allows both SSH and Telnet access, which does not meet the requirement of disabling Telnet.
- D. Incorrect.
This option permits all transport protocols, including SSH, Telnet, and others, which does not meet the requirement of restricting access to only SSH.