tftp is the simple file transfer protocol, which is the abbreviation of "Trivial File Transfer Protocol". It is a protocol in the "TCP/IP" protocol family used for simple file transfer between the client and the server. Provides uncomplicated and low-cost file transfer services; tftp does not have many functions of ordinary FTP. It can only obtain or write files from the file server, cannot list directories, does not perform authentication, and transmits 8-bit data.
The operating environment of this tutorial: Windows 10 system, Dell G3 computer.
TFTP (Trivial File Transfer Protocol, simple file transfer protocol)
TFTP is a member of the TCP/IP protocol family A protocol used for simple file transfers between clients and servers, providing an uncomplicated and inexpensive file transfer service. The port number is 69.
TFTP is a simple protocol for transferring files. It is implemented based on the UDP protocol, but we are not sure that some TFTP protocols are based on other transmission protocols. This protocol is designed for small file transfers. Therefore it does not have many of the features of the usual FTP, it can only get or write files from the file server, it cannot list directories, it does not authenticate, and it transfers 8-bit data. There are three modes in transmission: netascii, which is an 8-bit ASCII code form, and the other is octet, which is an 8-bit source data type; the last mail is no longer supported, and it returns the returned data directly to the user. Not saved as a file.
Extended knowledge
Features
Because TFTP uses UDP, and UDP uses IP, IP can also use other local communications method. Therefore, a TFTP packet will have the following segments: local media header, IP header, data header, TFTP header, and the rest is TFTP data. TFTP does not specify any data in the IP header, but it uses the source and destination ports and packet length fields in UDP. The packet identifier (TID) used by TFTP is used here as the port, so the TID must be between 0 and 65,535. We will discuss its initialization later. The TFTP header includes a two-byte operation code. This code indicates the type of packet. Let's take a look at the general TFTP packet format. We will discuss the relevant content in subsequent chapters.
--------------------------------------------------- | Local Medium | Internet | Datagram | TFTP | ---------------------------------------------------
TFTP does not have many functions of ordinary FTP. It can only obtain or write files from the file server. It does not have the function of listing directories, and it cannot authenticate users. It transmits 8-bit data. .
But TFTP also has two advantages of its own.
TFTP can be used in UDP environment; for example, when programs or files need to be downloaded to many machines at the same time, the TFTP protocol is often needed.
The TFTP code occupies a small amount of memory, which is very important for smaller computers or some special-purpose devices. These devices do not require a hard disk and only need to solidify TFTP, UDP and IP. A small capacity read-only memory is sufficient. When powered on, the device executes the code in the read-only memory and broadcasts a TFTP request on the network. The TFTP server on the network sends the response, which includes the executable binary. The device receives this file, places it into memory, and starts running the program. This approach increases flexibility and reduces overhead.
Normal termination
The end of the transfer is marked by DATA data, which includes 0-511 characters. This packet can be acknowledged by other data packets. The receiver can disconnect after sending an acknowledgment of the last data packet. Of course, it is better to wait appropriately. If the final confirmed packet is lost, it can be transmitted again. If the last packet is still received after sending the acknowledgment, it can be determined that the last acknowledgment is lost. The host that sent the last DATA packet must wait for an acknowledgment of this packet or timeout. If the response is ACK, the transfer is complete. If the sender times out and is not ready to resend and there is a problem with the receiver or network problem, the sending will end normally. Of course, it can also end abnormally during implementation, but the connection will be closed anyway.
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