Configuring FTP

File Transfer Protocol (FTP) is an application layer protocol based on the client/server model. It is used to transfer files from one host to another over an IP network, as shown in Figure 22.

FTP server uses TCP port 20 to transfer data and TCP port 21 to transfer control commands. For more information about FTP, see RFC 959.

FTP supports the following transfer modes:

• Binary mode—Used to transfer image files, such as .bin, and .btm files.

• ASCII mode—Used to transfer text files, such as .txt, .bat, and .cfg files.

By default, the transfer mode is binary.

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.

The FTP operation mode varies by FTP client program.

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.