Router(config)#service password-encryption
Applies a weak encryption to passwords
Router(config)#enable password cisco
Sets enable password to cisco
Router(config)#line con 0
...
Router(config-line)#password Cisco
Continue setting passwords as above
Router(config)#no service password-encryption
Turns off password encryption
Caution:
If you have turned on service password encryption, used it, and then turned it off, any passwords that you have encrypted will stay encrypted. New passwords will remain unencrypted.