You can set the password for a UNIX user to a special value, such as NP (no password) or * (no login) without affecting the user's Windows password. To do this, use nismap to change the Network Information Service (NIS) password entry for specific user, as follows:
nismap mod -e "username::uid:gid:gecos:/home/username:/login_shell" -k username passwd
nismap mod -e "username:*:uid:gid:gecos:/home/username:/login_shell" -k username passwd
nismap mod -e "username:*LK*:uid:gid:gecos:/home/username:/login_shell" -k username passwd