By default, the router stores all passwords in clear text and presents them in a human-readable format when you look at the router’s configuration. The service password-encryption command encrypts the passwords by using the Vigenere encryption algorithm.
Problem : You want to encrypt passwords so that they do not appear in plain text in the router configuration file.
Solution : To enable password encryption on a router, use the service password-encryption configuration command:
Router1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router1(config)#enable password oreilly
Router1(config)#line vty 0 4
Router1(config-line)#password cookbook
Router1(config-line)#line con 0
Router1(config-line)#password cookbook
Router1(config-line)#line aux 0
Router1(config-line)#password cookbook
Router1(config-line)#exit
Router1(config)#service password-encryption
Router1(config)#end
Router1#
