Hallo Kai,
es gibt noch einen Sicherheitstip:

If the QMAXSGNACN system value is set to 1, the QMAXSIGN system value applies to TELNET but not to FTP. If QMAXSGNACN is set to 2 or 3(values which disable the profile if the maximum sign on count is reached), FTP logon attempts are counted. In this case, a hacker can mount "denial of service" attack through FTP by repeatedly attempting to log on with an incorrect password until the user profile is disabled. For each unsuccessful attempt, the system writes a message CPF2234 to the QHST log. You can write a program to monitor the QHST log for message. If the program detects repeated attempts, it can end the FTP servers.