Migrating and syncing samba users
Samba maintains it’s own user and password database. If you want to synchronize samba users with system users pam_smbpass will to the trick.
Debian/Ubuntu:
sudo apt-get install libpam-smbpass
This package installs pam_smbpass.so and modifies pam.d common-auth and common-password scripts to keep system and samba users in sync.