08 October 2008

TFTP Server for Newbies

TFTP or Trivial File Transfer Protocol can be a very useful network management tool. Although it's a simplified version of FTP, but because of that simplicity it wins the heart of all network engineers.

You can use TFTP server for numerous purposes when relating it with network devices.
You can use it for uploading or downloading Cisco IOS or other network vendors' operating systems, backup configuration files, or even run firmwares or operating system over the network for IP Phones, network devices, etc. without storing them in the devices.

I think most if not all of the professionally managed networks are definitely using TFTP servers.

I quoted from wikipedia about the details and features of TFTP Servers:

  • 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 obsoleted by RFC1350.
  • 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.

You can find many free TFTP servers in the internet, most popular ones are:

WinAgents TFTP Server
SolarWinds TFTP Server
Kiwi CatTools - Network tools collection including TFTP Server

Personally I use the SolarWinds TFTP Server, don't get me wrong, every TFTP server you can find is easy to install and configure. I just use the one from SolarWinds because I have been using it from a very long time ago.

Up there in the post is the image of SolarWinds TFTP server when I used it to upload IOS image for recovery.

To use a TFTP server is fairly easy, just make sure your router can reach the computer you use for TFTP server, run the TFTP service in your computer, provide a space for placing your files to upload or download, and run the copy command from the router.