Information
The commands below change password encryption from md5 to sha512 (a much stronger hashing algorithm). All existing accounts will need to perform a password change to upgrade the stored hashes to the new algorithm.
The SHA-512 algorithm provides much stronger hashing than MD5, thus providing additional protection to the system by increasing the level of effort for an attacker to successfully determine passwords.
Note that these changes only apply to accounts configured on the local system.
Solution
Set password hashing algorithm to sha512. Many distributions provide tools for updating PAM configuration, consult your documentation for details. If no tooling is provided edit the appropriate /etc/pam.d/ configuration file and add or modify the pam_unix.so lines to include the sha512 option:
password required pam_unix.so sha512