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In our daily work, we can't do without uploading and downloading files, so what are the protocols for transferring files between different file systems? In this issue, let's learn about these three common file transfer protocols with the document.

01. FTP protocol FTP (File Transfer Protocol, File transfer Protocol) is a standard protocol for transferring files in computer networks. FTP is a client / server protocol. We usually connect the client to the server through the FTP client software and use the FTP protocol to upload and download files. The file transfer process is shown in the following figure:

01. The transport process server opens TCP (Transmission Control Protocol, Transmission Control Protocol) port 21 (standard) for FTP control connections and waits for FTP clients to connect. When the client needs to log in to the FTP server, establish a control connection with the server (port 21). The connection always waits for communication between the client and the server, passes the command from the client to the server, and returns a reply from the server.

Create a data connection whenever a file transfer is needed.

For example, sending a human file is equivalent to a FTP client, and the recipient is equivalent to a FTP server.

The document gentleman needs to send express delivery, only need to operate on the mobile phone, you can let the courier pick up, can also cancel the pick-up order at any time, this process is similar to the control connection. That is, the control connection is used to transmit control instructions and can also terminate the transmitted instructions in the course of transmission.

After picking up the package, the courier needs to be responsible for the transshipment of the package (data) until it is delivered. This process is similar to the data connection, that is, the data connection is used for the actual file transfer, closing the data connection after the transfer is complete, and ending the entire file transfer process.

02, characteristic security: FTP transmission process uses TCP plaintext transmission, there are security risks, for data with high security requirements, FTP service is not recommended.

Reliability: FTP uses TCP as the transport layer protocol for data transmission, which ensures the reliability of data transmission.

Connection oriented: FTP maintains a connection after establishing a connection until the connection is closed.

Authentication required: FTP servers usually require users to authenticate before they can transfer files to protect the security of the data.

Supported transfer mode: support binary mode and ASCII mode, can adapt to different types of file transfer.

Binary mode application scenario:

ASCII mode application scenarios: text files, HTML files, CGI scripts, cascading style sheet files, javascript files.

List of supported files: supports the operation of listing the contents of the directory.

Support for transferring large files: files of GB (Gigabyte, gigabyte) size can be transferred.

02. SFTP protocol SFTP (Secure File Transfer Protocol, secure File transfer Protocol) is a protocol used to securely transfer files in the computer network. In fact, it is an enhanced version of FTP, which specially uses an encrypted transmission technology to improve the security of data transmission.

01. During the transfer process, the client encrypts the file to be transferred by key, and then sends it to the SFTP server.

The SFTP server uses the key to decrypt the encrypted file and finally get the original file.

02. Characteristic security: SFTP uses the encryption mechanism of SSH (Secure Shell, secure Shell Protocol). SSH can provide a secure transmission environment for network services in an insecure network, which is equivalent to adding a protective cover to the file transfer channel, thus ensuring the secure transmission of data.

Reliability: the transmission process of SFTP is reliable. If the transfer is interrupted, it can recover from the last interruption without having to retransfer the entire file.

Connection oriented: SFTP maintains a connection after establishing a connection until the connection is closed.

Authentication required: SFTP requires that the client user must be authenticated by the server.

Supported transfer modes: binary mode and ASCII mode, can adapt to different types of file transfer.

List of supported files: supports the operation of listing the contents of the directory.

Support for transferring large files: files of GB (Gigabyte, gigabyte) size can be transferred.

03. TFTP Protocol TFTP (Trivial File Transfer Protocol, simple File transfer Protocol) is a protocol used to transfer simple files between the client and the server. It provides a file transfer service with no complexity and little overhead. It can only obtain or write files from the server.

01. During the transmission process, both the TFTP client and the TFTP server are the sender and receiver of the data. One side transmits the data to receive the reply, and the other party sends the reply to receive the data.

For example, it is similar to making a voice call with a small partner in our life, where one party makes a voice request and the other party can receive the voice.

02. Characteristic security: TFTP does not support any authentication mechanism, so the security is poor and needs to be used in a secure network.

Reliability: TFTP is based on UDP (User Datagram Protocol, user Datagram Protocol) protocol, without error recovery and retransmission mechanism, so it is unreliable.

Connectionless: TFTP is connectionless, meaning that each TFTP package is independent and does not require a connection.

Does not support authentication: TFTP does not support any authentication mechanism, so the security is poor and needs to be used in a secure network.

Supported transfer mode: support binary mode and ASCII mode, can adapt to different types of file transfer. Binary mode and ASCII mode can be adapted to different types of file transfer.

File list is not supported: TFTP does not support listing the contents of the directory, and users need to know the name of the file to download or upload.

Transfer of large files is not supported: TFTP can only transfer smaller files because it limits the size of packets.

04. Three protocol application scenarios. Next, the document will talk about the application scenarios of these three file transfer protocols to help deepen understanding.

Suppose the document needs to upload a company file from your computer to the company server. This is a common file transfer scenario that can be transferred using FTP, SFTP, or TFTP protocols.

When you need to transfer a team-building VLOG video file, you can use the FTP client to connect to the company server, enter a user name and password for authentication, and then upload the file. Because the FTP transmission is not encrypted, if the VLOG video contains sensitive information, other more secure protocols need to be considered.

When you need to transfer a confidential meeting screenshot file, you can use the SFTP client to connect to the company server, enter your user name and password or SSH key for authentication, and then use encrypted transfer to upload the file to the server. This method is more secure and suitable for situations where data security needs to be protected.

When the document needs to transmit firmware (program code solidified in the integrated circuit), it can be uploaded to the company server through the company's internal local network using the TFTP client. Because of the fast transmission speed and low bandwidth consumption of TFTP, the upload process can be completed quickly. It should be noted, however, that TFTP is weak in terms of security, so it is not suitable for transmitting sensitive information.

In conclusion, Mr. documentation compiled a table to facilitate your understanding of the main differences between the three agreements.

This article comes from the official account of Wechat: ZTE documents (ID:ztedoc)

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