To securely access a Cisco device using SSH, you must first configure a hostname and domain name, create a local username and password, and generate RSA keys. You then allow only SSH access using the "transport input ssh" command, which disables Telnet access. The example configuration shows defining the hostname and domain name, creating a local user, and enabling only SSH access. It is recommended to use SSH version 2 for more secure access.

1. Setting up SSH

2.  To enable secure access to your Cisco device, you can use
SSH instead of Telnet. SSH uses encryption to secure data
from eavesdropping.
 To enable SSH, the following steps are required:
1. Set up a hostname and a domain name
2. Configure local username and password
3. Generate RSA public and private keys
4. Allow only SSH access

3. The following example shows the configuration of the first
three steps:

4.  First, we have defined the device hostname by using
the hostname R1 command. Next, we have defined the
domain name by using the ip domain-name cisco command.
 After that, the local user is created by using the username
study password ccna command. Next, we need to enable only
SSH access to a device. This is done by using the transport
input ssh command:
If we use the transport input ssh command, the telnet access
to the device is automatically disabled.
 NOTE – you should use the more recent version of the protocol,
SSH version 2. This is done by using the ip ssh version 2 global
configuration command.