Definition
File eXchange protocol (FXP) is a specialized file transfer protocol that enables direct data transfer between two remote FTP (File Transfer Protocol) servers without routing through a client’s connection.
Unlike a standard FTP, where files transmit between a client (local) and a server (remote), FXP allows direct file transfers between two servers using FTP protocols.
How the File eXchange Protocol Works
FXP uses FTP protocol commands to coordinate server connections. The client initiates the process by directing the source server to connect with the target server and instructs it to transfer files directly. FTP commands like PASV (passive) and PORT handle this process.
Security Concerns
FXP can make servers vulnerable to unauthorized access. For it to work, both FTP servers must support and enable FXP. However, since servers must deactivate some security checks, they can become vulnerable to many risks, including FTP bounce attacks. That is why most FTP servers disable FXP by default.