If you have tried to setup SSH access on a new ASA, it might not have worked the way you wanted. That is because the RSA keys need to be generated first. To do that:
from configure terminal:
fw01/act(config)# crypto key generate rsaINFO: The name for the keys will be:Keypair generation process begin. Please wait…
And then configure SSH to be allowed from the inside interface:
fw01/act(config)# ssh (inser your ip) (insert your netmask) outside
Now you can configure AAA and setup your own username.
First, a username needs to be created:
fw01/act(config)# username leonardo password mypassword privilege 15
And then configure AAA:
fw01/act(config)# aaa authentication ssh console LOCAL