Please refer to the topic HTTP Proxies for more information on this.
To direct socket communications via an HTTP proxy, the ProxySettings of the client must be set appropriately. An example is shown below:
ProFTPClient ftp = new ProFTPClient();
ftp.getProxySettings().setProxyAddress("myinternalproxyaddress");
ftp.getProxySettings().setProxyPort(8080);
ftp.getProxySettings().setProxyType(ProxyType.HTTP);
Note that with HTTP proxies, FTP cannot be used in active (PORT) mode, as an HTTP proxy has no command to ask it to listen on a port on behalf of a client.
SecureFileTransferClient, SSLFTPClient, SSHFTPClient, and ProFTPClient all support the use of an HTTP proxy.