Controlling Access to Your Files

This page is part of Web Communications Guide to using FTP. It provides an overview of the Unix file security mechanism and how to use it to safely make files available on the Internet through FTP (File Transfer Protocol).

Your WebCom account is set up so that all files transferred to it (by you, other WebCom users, or anonymous users) or created within it are owned by you, and have their permissions set to deny anyone else access to them through FTP. This is a security feature that prevents anonymous users from taking advantage of writable directories or files to distribute illicit material. To make files available through FTP, their permissions must be changed after they are transferred or created. Directories are created by default with permissions that permit everyone to access them, but no one but the creator to write to them.

Unix classifies users by individual, group, and world. Permission to access files and directories is based on the category an individual user falls into, relative to the owner and group of the file or directory being accessed. Therefore, the term for configuring Unix file security is "setting file permissions". Note that these permissions do not have any effect on whether or not someone can access your files through the World Wide Web. For information on that subject, see Permissions and Access to Files through the WWW.

For the purpose of securing your account on WebCom from other users, the group and world categories should be treated identically (and are, if you are using the WebCom File Manager).

If you simply wish to make files available (or unavailable) to the public through FTP, then we strongly recommend using the WebCom File Manager. It permits you to change public access permissions using your graphical browser.

If you prefer to use your FTP client to manage permissions, see Changing Permissions Using an FTP Client.