If a client encounters problems when connecting to your FTP server, one of the first things you might want to check is your FTP data transfer mode. Depending on certain network configurations, this mode should be set to either active or passive. In this post, you’ll understand the salient points of active and passive FTP and learn how to avoid connectivity issues associated with them.
Note: For those who have landed on this page some time in the past, we’d like to inform you that we’ve recently added a new section discussing the passive FTP port range and how large it should be.
Before we talk about which mode is best for what scenario, let’s first cover one important topic: the two channels of an FTP session.