Configuring FTP
File Transfer Protocol (FTP) is an application layer protocol for transferring files from one host to another over an IP network, as shown in Figure 19. It uses TCP port 20 to transfer data and TCP port 21 to transfer control commands. For more information about FTP, see RFC 959.
FTP is based on the client/server model. The device can act as the FTP server or FTP client. Make sure the FTP server and the FTP client can reach each other before establishing the FTP connection.
Figure 19: FTP application scenario
FTP supports the following transfer modes:
Binary mode—Used to non-text files, such as .app, .bin, and .btm files.
ASCII mode—Used to transfer text files, such as .txt, .bat, and .cfg files.
When the device acts as the FTP client, you can set the transfer mode (binary by default). When the device acts as the FTP server, the transfer mode is determined by the FTP client.
FTP can operate in either of the following modes:
Active mode (PORT)—The FTP server initiates the TCP connection. This mode is not suitable when the FTP client is behind a firewall, for example, when the FTP client resides in a private network.
Passive mode (PASV)—The FTP client initiates the TCP connection. This mode is not suitable when the server does not allow the client to use a random unprivileged port greater than 1024.
FTP operation mode varies depending on the FTP client program.