TFTP flash

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This article describes how to do a initial flash or a TFTP recovery flash for your device.

  • make sure you have a TFTP client installed (linux package, e.g. from or Windows GUI TFTP Utility)
  • connect your PC to one of the router's LAN ports using ethernet cable
    • tip: a hub or switch in-between your PC and router may be helpful, but it's optional
  • make sure that your PC has a fixed IP address in the same network as your router, eg. Router:, PC: (example w/picture)
  • get the latest dd-wrt release here (plz use the mini version for devices with 4mb flash & the micro version for 2mb flash devices)


The following example is for a belkin f5d130uk after a bricked update... NOTE: they already have a bootloader built in, no need for redboot...

Command Line

  • ping the router permanently, by running in Start > Run:
 ping -t -t

and see if it is responding, e.g. like this

 64 bytes from icmp_seq=1 ttl=64 time=2.90 ms
 64 bytes from icmp_seq=2 ttl=64 time=0.264 ms
 64 bytes from icmp_seq=3 ttl=64 time=1.44 ms
  • reboot the router via web-if or powercycle (the ping response will stop)
  • if you see the the first ping response again ...
 From icmp_seq=1 Destination Host Unreachable
 From icmp_seq=2 Destination Host Unreachable
 64 bytes from icmp_seq=3 ttl=128 time=2.90 ms
 64 bytes from icmp_seq=4 ttl=128 time=3.50 ms
 64 bytes from icmp_seq=5 ttl=128 time=0.90 ms

... you will have to start the tftp upload in binary mode immediately after the first pings responses. the ttl of the boot tftp server will be 100 or 128. It usually does 5 pings responsed, after that it will boot the firmware in flash, this is the right time to flash (the ttl of ddwrt is only 64). if the upload doesn't work the first time, then you have to try the first steps again. you have to be very fast! ;-) maybe you will have to reset the device via reset button a few times to get the tftp-boot working (siemens, belkin and similar hw).

 tftp -i put dd-wrt.vXX_XXX.XXX
  • wait a few seconds (be patient! dont reset the router! keep waiting!) when the upload is successful, change your computer IP to, and the router will start responding at with dd-wrt
  • username: root / pw: admin
  • always do a hardware factory reset after the successful flashing!

Linksys TFTP GUI

Linksys has a GUI flash utility which may be tftp.exe on and can set the number of retries. It works with many other brands of routers too, not just Linksys.

Here are the setup and use instructions for the TFTP utility. An updated copy can be found here TFTP2

  1. Set your computer hardware adapter to a Static IP address within the same subnet as the router's original firmware (ex...set a static of if your router's default IP is Set the Mask to
  2. Start the TFTP utility.
    • The Server/IP address is that of the router being flashed.
    • Leave the Password blank.
    • Navigate and select the firmware you wish to flash.
    • Set retries to 10.
  3. Now plug the Ethernet Cable from your computer into a LAN port of the router.
  4. Unplug the router....plug it back in...immediately hit the Upgrade button on the TFTP utility.
    • If the router does not flash immediately....stop the attempts and vary the timing from when you plug the unit the time you hit the start button. I have had good luck flashing within the first 1/2 second of reapplying powering the device.
    • Tip: Ping the router continuously. Start > Run > ping -t 192.168.x.x -w 10 Power cycle the router (or tap the reset button) then press Upgrade as soon as you get the first ping reply.
  5. Once it flashes and you receive the Success message....wait for a full 2 minutes while the new firmware flash configures itself...DO NOT depower the router!
  6. After the 2 minutes are a Hard reset or 30/30/30 on the router...then configure at (dd-wrt's default IP address). The default dd-wrt Username/Password is root/admin.

Linux and Mac OS X

OS X ships with a command-line TFTP client.
In Linux, tftp can generally be installed with whatever package manager your distribution uses.
on suse:

 smart install tftp

on fedora:

 yum install tftp

on ubuntu

 sudo apt-get install tftp

The tftp client for Linux and OS X is very similar. When invoked, it gives the user a prompt and takes commands from the standard input.
Binary mode can be set with command-line flags - in OS X, the "-e" flag sets binary mode (among other things which are less important), and in Linux "-m binary". Binary can be set from the prompt in either (this is done below for consistency).

Typical usage looks like:

 tftp 192.168.x.x
 > binary
 > put dd-wrt.vXX_XXX.XXX

Because the transfer must be initiated in a narrow time window during the router's bootup, tftp's retransmit option is useful. In the following sequence of commands, tftp will retry to send the file every second for one minute. This can be issued just before the router is booted, so that it will retry to send every second while the router boots.

 tftp 192.168.x.x
 > binary
 > rexmt 1
 > timeout 60
 > put dd-wrt.vXX_XXX.XXX

If it worked, it will say something like "Sent 1769472 bytes in 9.0 seconds"

If it didn't work, it will say "Transfer timed out." This is often because it cannot connect to the IP. Make sure you have manually set your computer's IP to one in the router's subnet.

You can quit tftp with the 'quit' command or hitting ctrl+D.

Many Linksys routers require a special version of tftp that has a simple form of authentication. You can download and compile a special version of tftp that works on these routers from: (you will need to unpack the tarball and compile the program)

Another way of doing this is using atftp. You can search it in your package manager. On Ubuntu:

sudo aptitude install atftp

On Debian (as root):

aptitude install atftp

On Fedora (as root):

yum install atftp

On Suse (as root):

smart install atftp 

Then you go to the folder where you downloaded the official Linksys firmware, for instance if you downloaded it in your desktop:

cd ~Desktop

Unrar the file, for instance if the file is WRT54GL_v4.30.11_012_ETSI_EN_code.rar

unrar x WRT54GL_v4.30.11_012_ETSI_EN_code.rar

Rename the firmware to code.bin.

cp WRT54GL_v4.30.11_012_ETSI_EN_code.bin code.bin

Then you prepare this command (do not press enter yet):

atftp --option "mode octet" --option "timeout  60" --verbose --trace -p -l code.bin

Disconnect all your network cables from your router, only leaving one from the computer to the router. Then open another terminal and ping to


Then unplug and plug back the energy supply and when you see the first ping response from the router you must hit enter in the atftp terminal. Good luck! If everything is allright, you should see a lot of output, from all the transference. At the end you should see the orange/yellow light up. Then you should wait a couple more minutes (you never know what's happening there :D) and then try the Hard reset aka 30/30/30

About the atftp command: we are putting (-p) a local file (-l) called code.bin to the IP asking for fully information (verbose) and showing all packages (trace), also that it must be trying for one minute (timeout 60) and in octet mode. Remember, if you get "code pattern error", try with the official Linksys firmware. More information:

man atftp 
atftp --help

Important: you should allways try atftp with the official firmware and then flashing to dd-wrt with the HTTP webpage on Administration, "Upgrade Firmware"; specially if you get "code pattern error".

Note: if you use Gnome or KDE you can get problems while trying to put your static IP. Most of the times, applications like NetworkManager (aka nm-applet) or knetworkmanager will try to get a dynamic IP, so you should first kill them. For example:

sudo killall NetworkManager


sudo killall nm-applet

Related Links

Recover from a Bad Flash

Flash Your Siemens SE505

TFTP Flashing a Belkin F5D7230 - more detailed notes on flashing the F5D7230 (v1000, specifically)

Using Ubuntu and tftp to flash an Asus WL-500W