can we write program to get password of linux user

Question

can we write a program in java to get usernames and passwords

Answer 1

No, we can't.

Answer 2

You can get usernames by reading /etc/passwd file.

You cannot get passwords unless you try to decrypt them, and that's not practical...

Answer 3

Without a brute-force attack and at least a list of the encrypted passwords, you are out of luck.

Also read this http://www.linux.org/docs/ldp/howto/Security-HOWTO/password-security.html

and this http://www.cyberciti.biz/faq/understanding-etcpasswd-file-format/