Cisco IOS Router Basic Configuration

Let me give you a complete example:

R2(config)#ip domain-name networklessons.local

R2(config)#crypto key generate rsa             

The name for the keys will be: R2.networklessons.local
Choose the size of the key modulus in the range of 360 to 2048 for your
General Purpose Keys. Choosing a key modulus greater than 512 may take
a few minutes.

How many bits in the modulus [512]: 1024
% Generating 1024 bit RSA keys, keys will be non-exportable…[OK]

R2(config)#username rene secret mysecretkey

R2(config)#line vty 0 4
R2(config-line)#login local
R2(config-line)#transport input ssh

And then on another router:

R1#ssh -l rene 192.168.12.2

Password: 

R2>