TFTP Server modes not working

Question

I am creating a tftp application on linux(ubuntu 12.04). I tried atftp server on linux and captured packets on wireshark for understanding the functionality of tftp server. I am confused in mode option. I tried every mode of tftp server like netascii, octet, mail but i am getting plain text on the wire. Please Help me out by providing any link for it. do i have to encode or decode on both the ends before sending the chunks of data.

Answer 1

please read RFC 1350

netascii (8 bit ascii)
octet    (raw 8 bit bytes)
mail     (The mail mode is obsolete and should not be implemented or used.)

A host which receives netascii mode data must translate the data to its own format. Octet mode is used to transfer a file that is in the 8-bit format of the machine from which the file is being transferred. It is assumed that each type of machine has a single 8-bit format that is more common, and that that format is chosen. For example, on a DEC-20, a 36 bit machine, this is four 8-bit bytes to a word with four bits of breakage. If a host receives a octet file and then returns it, the returned file must be identical to the original. Mail mode uses the name of a mail recipient in place of a file and must begin with a WRQ. Otherwise it is identical to netascii mode. The mail recipient string should be of the form "username" or "username@hostname". If the second form is used, it allows the option of mail forwarding by a relay computer.

You do not have to encode your payload; If you are in a PC environment you will not see a difference in a wireshark capture when changing the encoding.