The most common use of FTP-Proxy will probably be "inbound" FTP traffic. This means that clients from an "outside" world seek access to a "local" FTP server. Nevertheless, FTP-Proxy supports also an "outbound" mode, where clients have more control over the FTP connections.
The concept of "outbound" traffic is based on the increased level
of trust that users enjoy. When setting the AllowMagicUser
config option to "yes" and allowing the "@" and ":" characters as
part of the USER command argument, users can determine the
destination server's address and port with the USER command. All
they have to do is to append the host name, separated by the "@" sign,
optionally followed by a colon and the port. These compartments will
be removed from the name and evaluated as destination.