I have added the option --ftp to redir to allow support of the ftp
protocol. This means that redir not only support the main ftp session, but
also manage properly the ftp-data sub-session. When redir see the PORT
command, it create a new one, telling the ftp server to connect to
the redir machine on a new port. When it receives that connection, it
connect to the client using the original PORT command.

Some validation are made. When a connection is done to the listening
sub-session, it makes sure it is coming from the ftp server. If not, the
connection is dropped and a message is sent to syslog.

Further the PORT command is validated also. It has to specify the
same IP number as the ftp client. If not, the session is terminated and
a message is sent to syslog.

To use this option to redir an ftp session, simply add the --ftp option.
That's all.

The goal of this is to let you hide a ftp server on a private network
and let access from the internet.

Note that both active and passive ftp session are supported!

Have fun!

Jacques Gelinas
September 1998
jack@solucorp.qc.ca