TFTP

仕事でちょっとつまったのでメモ。
ちなみにFTPの簡易版の様なものらしく、プロトコルはFTPとは全然違う。

ちょっと大きいファイルを転送するとファイルサイズがおかしくなる。
調べてみたら、どうやらファイルサイズの最大サイズが32MBまでらしい。
RFC 2348では拡張されて4GBまでらしい。

http://en.wikipedia.org/wiki/Trivial_File_Transfer_Protocol

Some details of TFTP:

    * It uses UDP port 69 as its transport protocol (unlike FTP which uses TCP port 21).
    * It cannot list directory contents.
    * It has no authentication or encryption mechanisms.
    * It is used to read files from, or write files to, a remote server.
    * It supports three different transfer modes, "netascii", "octet" and "mail", with the first two corresponding to the "ASCII" and "image" (binary) modes of the FTP protocol; the third is now obsolete and is rarely used.
    * The original protocol has a file size limit of 32 MB, although this was extended when RFC 2347 introduced option negotiation, which was used in RFC 2348 to introduce block-size negotiation in 1998 (allowing a maximum of 4 GB and potentially higher throughput). If the server and client support block number wraparound, file size is essentially unlimited.
    * Since TFTP utilizes UDP, it has to supply its own transport and session support. Each file transferred via TFTP constitutes an independent exchange. That transfer is performed in lock-step, with only one packet (either a block of data, or an 'acknowledgement') ever in flight on the network at any time. Due to this lack of windowing, TFTP provides low throughput over high latency links.
    * Due to the lack of security, it is dangerous over the open Internet. Thus, TFTP is generally only used on private, local networks.