You should look in the sample-configurations/ directory from your distribution tarball. Basically, you'll need to create another user on your system for the guest/anonymous ftp login. For security reasons, it's very important that you make sure the user account either has a password or has an "unmatchable" password. The root directory of the guest/anonymous account doesn't have to be the user's directory, but it makes sense to do so. After you have created the account, put something like the following in your /etc/proftpd.conf file (assuming the new user/group name is private/private):
Example 10-1. Access control using LIMIT
<Anonymous ~private> AnonRequirePassword off User private Group private RequireValidShell off <Directory *> <Limit WRITE> DenyAll </Limit> </Directory> </Anonymous>
This will allow ftp clients to login to your site with the username "private" and their e-mail address as a password. You can change the AnonRequirePassword directive to "on" if you want clients to be forced to transmit the correct password for the 'private' account. This sample configuration allows clients to change into, list and read all directories, but denies write access of any kind.