Sorry for the language level - I do not speak English. On the server will be optionally available to all users of content management systems: Drupal and Concrete5. Question: how is it best to make use of the advantages of working with ISPConfig3. Best if it was possible to access via ftp to the subfolders with the files of users, but not to the core CMS, and the administrator must be ftp access to the core CMS. Method 1 - better. Multidomain CMS for multiple users - core in one folder - folders with files of users - with symlinks to the core - how best to do with ISPConfig3? Manually add symlinks in the filesystem for each user web folders? Method 2 - worse. Multidomain CMS (with core) for multiple users without ftp access - how to do it in one folder? Domain Aliases in ISPConfig3 as other domains (in the same folder) do not work well - some scripts in CMS incorrectly interpret the path (correctly for the base domain).
In my opinion, it is best to have one installation of Drupal core with multiple domains using that core installation. There is no need for symlinks. The Drupal installation instructions are pretty good. I was able to setup a multi-site installation without any issues. This might be a good topic for a tutorial. I'll try to write one within the next week. Until then, take a look at the installation instructions at drupal.org and see if you can figure it out.