To configure Switch1 to allow SSH connections and prohibit Telnet connections, the network administrator should modify the configuration of the VTY lines (virtual terminal lines) to only allow SSH as a transport input protocol. Specifically, the administrator needs to change the "transport input" command under the VTY line configuration from allowing all protocols (which includes Telnet) to allow only SSH. This is done by setting:
line vty 0 15
transport input ssh
This configuration will enable SSH access while automatically disabling Telnet access on the switch's VTY lines. Additionally, the SSH configuration prerequisites should be met, such as setting a hostname, domain name, generating RSA keys, and enabling SSH version 2. Thus, the key change is to modify the transport input command under line vty 0 15 to "transport input ssh", which will satisfy the requirement to allow only SSH connections and prohibit Telnet connections on Switch1.
