Trivial File Transfer Protocol (TFTP) is a protocol that allows data files to be transferred from one device to another using the connectionless protocol, UDP. TFTP uses UDP port number 69.
TFTP is typically used in environments where bandwidth is not a major concern and IP packets that are lost can be resent by the higher layers (typically the application layer). TFTP has little security. In fact, the only security available to TFTP transfer is defining the directory on the host TFTP device and the filenames that will be transferred.
TFTP has no method to authenticate username or password; the TFTP packet has no field enabling the exchange of username or password between two TCP/IP hosts.
TFTP directory security ...