□ System user's password is recoreded in second field of /etc/shadow
□ Format : [$Hash algorithm][$salt][$Hash algorithm result]
○ Hash algorithm
- $1 : MD5
- $2 / $2a / $2y : Blowfish
- $5 : SHA-256
- $6 : SHA-512
○ salt : This is a random value, This makes it have a different hash value of the same password.
○ hash algorithm result : This is the result of "password" + "salt" into a hash function.