There are a number of services and tools that you can secure on a per-user basis. I divide them into two categories. Some services, such as FTP servers, are customizable on a per-user basis. Others may be secured based on user accounts.
As there are a substantial number of Linux network services, I can only describe securing by service in general terms. I provide an example of securing by user on an Apache and an FTP server.
If you want to secure by user on a shared NFS directory, explore an earlier annoyance in this chapter, "The Boss Wants to Set Up a Special Group of Users." Once you set up a special group and directory, you can share the associated directory with other Linux/Unix systems on your network using NFS. Assuming you have a single database of users and groups, such as the LDAP or Microsoft database mentioned near the beginning of this chapter, the way you configure your special group applies to all systems.
There are a variety of FTP services available. Many allow you to configure various forms of access, including:
Anonymous-only, which limits access to the default FTP data directory
Local user access, which allows users to log in to their accounts via FTP
Whatever FTP server you choose, be aware that FTP has a variety of security issues. Choose your FTP server carefully.
However, one reasonably secure solution is vsFTP. It is the default FTP server on Red Hat and Fedora distributions, and it is available for ...