Restrict a users access to all directories but one

So there is a user that was created by root, and it pretty much has access to most/all directories on the system, we want to use this user only for ftp via lftp to read a certain file on the server that this user is located, let's call it config-server. so all the other servers, have scripts that will use lftp/ftp to access the config-server using this user to read the desired config file. As the user and password will be saved on the other servers, we want to restrict this users access to all other unnecessary directories, and no we don't want to restrict the users ftp access, we want to restrict the user itself. My goal is to do it at once or at least once for each mount point, like configuring his /her access globally once to 000, then go the the desired directory and give him read access to that directory only. so how can I do this globally? is it possible? I thought I could use recursive chmod/setfacl on all directories/mountpoints while signed in as root, and then as root, give that user access to the config files path? is this a viable solution, or does it have risks. if not, please share your solution. Note: We have somewhat 74 servers, which nullifies the point of storing the config on each server separately. EDIT: Server OS is Redhat 6.9 (or later for other servers). Also the access method used in the script would be ftp, but like I said since the user and password is present in the scripts that are on the other servers, we should prevent the user overall access, some one might use ssh, or even direct login, and we can't be held responsible for allowing that to happen, also we have limited access to most of our servers (configuration wise), this is one of the few which we do have the root access and OS is not managed by another team. But we ourselves will need to be able to login to this user ( can't complicate it too much, not every member that is added to the team has good linux/OS knowledge Ironically, right now two new members, trained by me and my ex-colleague in linux, one which is IT student, still didn't know what command is used to switch user, both use right click to copy and paste :| ).