This article will explain the differences between Active and Passive FTP modes. Active mode is used for servers with tight security.
Security is a major concern with any computer connected to the internet, therefore any computer connected to the internet should be protected by a Firewall. In order to connect to certain services, such as FTP, you have to allow those connections in the Firewall, on both the Client and Server side.
Although a client's computer may not have a firewall enabled, a server should always have this enabled for maximum security.In order to connect to an FTP server that has a firewall enabled, you have to connect using a specific connection mode in your FTP program.
There are different connection modes to choose from when connecting to an FTP server, typically either "Active" or "Passive" mode.
Active mode is beneficial to the FTP Server's security, while Passive mode typically requires less configuration changes on the Client's side.