ioFTPD does kill stalled connections with !username at login. But... some ghost connections are caused by other applications that screw up the tcp/ip stack. Such as netlimiter, panda av, mcafee etc.
Als if the client is at that moment runnig a script then it can also not be killed. The script must finish. So therefor I wrote ioProcess with which you can view running processes under io and you can kill for example all profcesses that run longer then 5 minutes.