While fighting with DB2 denying logins I had to change the default hash algorithm used to store passwords in /etc/shadow.
As far as I know (and as grep -i -r "sha512" /etc/* tells me
), there are two files that carry this information.
Namely /etc/pam.d/common-password and
/etc/login.defs.
To change the algorithm from sha512 (which shifts as the default in the new Ubuntu releases) change this:
/etc/pam.d/common-password
password [success=1 default=ignore] pam_unix.so obscure sha512
to
password [success=1 default=ignore] pam_unix.so obscure md5
/etc/login.defs
ENCRYPT_METHOD SHA512
to
ENCRYPT_METHOD MD5