About File eXchange Protocol (FXP)
Description
File eXchange Protocol (FXP) is a method of data transfer which uses the FTP protocol to transfer data from one remote server to another (inter-server) without routing this data through the client's connection. Conventional FTP involves a single server and a single client; all data transmission is done between these two. In the FXP session, a client maintains a standard FTP connection to two servers, and can direct either server to connect to the other to initiate a data transfer. The advantage of using FXP over FTP is evident when a high-bandwidth server demands resources from another high-bandwidth server, but only a low-bandwidth client, such as a network administrator working away from location, has the authority to access the resources on both servers.
Risks
Enabling FXP support, however, can make a server vulnerable to an exploit known as FTP bounce. FXP is also frequently used for warez exchange. As a result of this, FTP server software often has FXP disabled by default.
FXP over SSL
Some FTP clients allow FXP data transfers to be encrypted in addition to the command connection (used to issue commands to the FTP server).
