FTP (File Transfer Protocol)

kc@example.com (kc kim) — Sun, 03 Apr 2022 18:02:00 +0900

FTP

FTP stands for File Transfer Protocol and is a communication protocol first released in 1971 so computers could exchange files over TCP/IP networks.
It is a service used to transfer files on the Internet. While Telnet is a service used to connect to and use another computer, FTP is used to transfer files to a server computer or to receive files from a server computer onto your own computer.

FTP is still widely used because it can transfer files quickly and reliably. To overcome the disadvantage of having to learn all commands, as with Telnet, dedicated FTP programs appeared and made it convenient to use.

How FTP Works

FTP is a client-server protocol. When the client requests a file, the server provides the requested file. Therefore, two basic channels are required to establish an FTP connection.

One channel is the command channel, which sends commands and basic information such as which files can be accessed.
The other channel is the data channel, which transfers file data between two devices.

To establish a connection, the user must provide login information for the FTP server, and FTP generally uses port 21 as its default communication mode.

FTP Connection Modes

There are two FTP connection modes: active mode and passive mode.

Active mode
- The server takes an active role in approving data requests.
- In active mode, problems caused by firewalls often occur. If a third party attempts to access an unauthorized session, that session is blocked.
Passive mode
- In passive mode, if a third party attempts to access an unauthorized session, the server does not actively maintain the connection.
- In other words, the user sets up both the data channel and the command channel. The server basically only “listens” and does not actively participate, allowing another device to handle most of the work.

FTP Connection Clients

FileZilla: the most widely used free program, available for Windows and macOS.
WinSCP: a free program developed for Windows.

Advantages and Disadvantages of FTP

Advantages
- Multiple files can be transferred at the same time.
- If the connection is lost, the transfer can be restarted.
- Transfer schedules can be reserved.
Disadvantages
- It is vulnerable in terms of security.

What Is SFTP?

FTP was developed in the 1970s, before most of the cybersecurity measures we use today were developed. Because it was not designed as a security protocol, FTP transfers do not encrypt files. As a result, passwords, usernames, and other sensitive data can be read relatively easily through packet capture attacks on data packets.

SFTP (SSH File Transfer Protocol) is a separate protocol that provides highly secure file transfer through a Secure Shell (SSH) data stream. Unlike FTP clients that use port 21, SFTP uses port 22. Because of FTP’s weak security, many people prefer SFTP, which provides security features by default and uses SSH connections.

devkuma – FTP