To configure SSH on a Cisco device you need to ensure you have the following set:

  • ip domain-name <domain>
  • hostname <hostname>

Once you have these two configured you need to generate the keys that will be used for encryption, this is achieved by the following command:

Router(config)#crypto key generate rsa general-keys modulus 1024
Router(config)#ip ssh time-out 10
Router(config)#ip ssh authentication-retries 3

Under line vty 0 4 you need to enable SSH only

Router(config-line)#transport input none
Router(config-line)#transport input ssh