This resolves a problem when connecting through Apache module
proxy_ftp_module. The problem turned out to be a problem with the EPSV
command, an extension to the FTP protocol that is used by some newer FTP clients.
On an unrelated matter: I had started work on a TFTPD (trivial FTP)
server, when I realised that OS/2 already handles this case, so that
project has been scrapped.