TRIVIAL FILE TRANSFER PROTOCOL (TFTP)

Trivial File Transfer Protocol (TFTP)

TFTP (Trivial File Transfer Protocol)

Introduction

A file transfer protocol with minimum capability and negligible overhead used on the Internet. It is a subset of FTP but does not provide password protection or user directory capability(Kozierok 2005, 82). It uses the User Datagram Protocol (UDP) to quickly send files across the network. The message is broken into numbered blocks that are transmitted to the destination one at a time.

Discussion

Trivial FTP is mainly used for booting diskless clients. These are computers that have no mass-storage device (such as a hard drive) attached. Instead, they carry a small firmware OS, typically burnt onto an EPROM (though other options exist). As these operating systems are typically very simple (due to space restrictions), the protocol is designed to be as simple as is possible, providing a minimal set of functionality needed to send and retrieve files. (Blank 2002, 25)

Thus,

TFTP does not provide:

Authentification. Any client may connect to the server and send/retrieve files

Directory browsing. You must supply the absolute path when referring to files.

Persistant connections. A TFTP client only opens a connection when sending or receiving a file, and closes it when finished.

As well, the protocol is built on top of UDP rather than TCP, as is the case with FTP. Actually, TFTP implements a simple stop-and-wait ARQ (automatic repeat requests) protocol. A file is transmitted in 512-byte datagrams, and each datagram must be explicitly acknowledged before the next packet is transmitted. (Farrel 2004, 96)

If you are running a Linux distribution, odds are good that it came with a TFTP server. First, change to root and make a new directory somewhere in the filesystem (this will be the upload/download directory), and put a random file into it. Then, start the server daemon process:

root@zork:~> mkdir /usr/tftp

root@zork:~> ...