Most FTP servers work in passive mode, since this makes it easier for you to upload a file. In "passive" transfer mode, you can sit behind a firewall. However, in "active" mode, it is up to you to work around your firewall to upload a file. To simplify the upload process, Yahoo!'s FTP server follows this standard and can only accept passive transfers. Please be sure your FTP server is set to "passive" transfer when you upload your travel data feed.