A "clean install" means that you have installed the OS and that your server can communicate with other computers via the internet (network connectivity has been established). If you performed a full server install minus the www services (Apache web server), then you should be fine.
A "clean server" means that you are not yet using the server on which you are attempting to install the Plesk Server Administrator for anything else, such as a web server, e-mail server, etc.
For advanced users: To install the standard build of Plesk on your server, please ensure that you have the following binaries in one of the following paths:
/bin/sh: echo, printf, cat, cp, rm mv, kill, chown, chmod, sleep, ln, grep, egrep, sed, awk, tar, uudecode, uncompress (Solaris, BSDI),
gzip (Linux, FreeBSD)
Also, your server must have a properly configured and functioning internet superdaemon (
xinetd) with remote access (telnet, SSH), if desired, as well as standard utilities for user and group adding. In addition, your system must have standard libraries properly installed in
/usr/lib/ and have MD5 shadow password support.
It is important to understand that Plesk does not control every aspect of your server. Plesk itself is secure within the context of its usage; however, a standard operating system installation is inherently insecure and requires manual user intervention to ensure the security of a server. Administrators must take security precautions within their operating system. Specifically, you should consult documentation on the appropriate Linux or UNIX OS running on your server, especially those documents relating to remote access and firewall security.