I have a D-Link router. Its software (firmware) causes a lot of problems so I try to update it.

My router model is DSL-2730U so I downloaded the original firmware from this site: http://www.dlinkmea.com/site/index.php/site/productDetails/234

When I update the software, it says that the file is illegal. I really need to update it because what I use now is not the original firmware and does not work properly.

I would like to know what does it mean by "Illegal" ? and What should I do to make it legal ? or where can I get a good firmware ?

Here are two pictures that describe my issue :

enter image description here

enter image description here

  • 10
    The message simply indicates the firmware isn't a valid firmware for your device..
    – Ramhound
    Commented Aug 8, 2015 at 2:04
  • 1
    At first I thought this was a question regarding wifi router channels.
    – March Ho
    Commented Aug 8, 2015 at 5:30
  • Are you connected wireless or wired to the router when attempting upgrade?
    – Moab
    Commented Aug 14, 2015 at 22:27
  • @Moab I'm connected wired to the router when attempting to upgrade Commented Aug 15, 2015 at 3:13
  • "what I use now is not the original firmware" does this mean you were able to update it some time ago? Or are you referring to ISP-branded firmware (which you never changed yourself)?
    – Arjan
    Commented Aug 17, 2015 at 10:35

4 Answers 4

  • First check your router firmware version and the downloaded version, sometimes you can't UPDATE to the newest firmware, you must look if they recommend an old version before the newest one.

If that router from ISP, it mean's they locked your router. you have three options to flash it with other version.

First method By using SSH commands most ISP left backdoor ports, you can use that method to un-break your router. Download the firmware to the router's /tmp directory with wget or scp.

cd /tmp
wget http://www.dd-wrt.com/dd-wrtv2/downloads/stable/dd-wrt.v2x_generic.bin

you could use the mounted share if you have one, and simply download the file there.

Compare the MD5 checksum of the original and the downloaded file.

md5sum dd-wrt.v2x_generic.bin

Write the firmware to flash.

write dd-wrt.v2x_generic.bin linux



Second method by flash your router with DD-WRT, Tomato or OPEN-WRT "open source firmware" I recommend DD-WRT it's more easy than other open source firmware and stable check their websites to find what firmware can work on your router, open source firmware can pass your ISP Lock.

The last method By using serial ports to flash your router, gives you the fully control of everything, this method can break any router, no close doors or locked routers anymore :)

Most factories left serial port on the main circuit board to test/troubleshoot their product. Sometimes you must solder wires to the ports, Like what I did in the PIC below, check My blog if your want more info about soldering your wires. enter image description here

and sometimes they are ready to use enter image description here

Now you need something called Arduino "Micro-controller" We will use it to make a communication between your PC and your router over the serial port. Connect your Arduino to your router like this TX-------RX




WARNING DON'T connect VCC to 5V

  • Connecting your LAN Cable from the Router to your PC
  • Download TFTP

  • Download firmware DD-WRT/Open-WRT or what ever you want for your Router.

  • Extract TFTP and insert Firmware openwrt "or what ever" to same folder TFTP extract.
  • change your static Computer IP
  • Run TFTP
  • choose the current directory to the firmware you download
  • change server to this IP
  • Connecting your computer with the Router via Putty
  • Connection type = serial
  • serial line = COM same com arduino detection into your computer speed = 115200
  • In progress booting your router and type "tpl" in command prompt putty interface

IP Setting for your lan card "all that inside TFTP"

  • Setting IP server: setenv serverip
  • Setting IP Mobile Router : setenv ipaddr

flash your Router with this command

tftpboot 0x80000000 openwrt-ar71xx-generic-tl-mr3020-v1-squashfs-factory.bin

after flashing type this command

1. erase 0x9f020000 +0x3c0000 (enter)
2. cp.b 0x80000000 0x9f020000 0x3c0000 (enter)
3. bootm 9f020000 (enter)

router reboot processing.....

That's it


If your router can't have WAN-IP after you figure out all settings, you need something called 30-30-30 Hard reset, sometimes your old firmware will stuck inside your NVRAM they call that Dirty NVRAM, 30-30-30 hard reset will clean your old firmware completely "that's for dd-wrt" firmware"

  • 1
    Wow. This answer though. +1
    – AndrewL64
    Commented Dec 3, 2016 at 17:32

Illegal in this case means a format not recognised by the router. The router checks the image file before installing it and it found it contains a format it does not recognise.

Reasons for this can be:

  • the image is meant for a different type of router or a newer version of your router
  • the image is corrupt
  • the image is compressed

If the image is compressed it means that image is inside a zip-file or other type of archive and must be uncompressed first before it can be used.

I saw that the download page you linked to offers the images as IMG and 7Z. The 7Z images are compressed using 7-zip and must (very likely) be uncompressed before they can be used to yield an IMGfile. The IMG file is then used to upgrade your router.

  • I think the image is not corrupt because I downloaded it many times and I extracted it using win rar. The download page I linked contains the router model which is DSL-2730U. Would you give me a method or a software to setup the firmware without using the GUI ( the web interface), please? Commented Aug 9, 2015 at 0:51
  • 2
    @hagen-von-eitzen could be right. You modem could be locked by your ISP. Google seems to confirm that you are not the only one struggling with that. As it is your modem, they should give you an image to unlock the modem. Maybe read the fine print of your contract with the ISP first: it might have a clause regarding your rights with respect to the modem and its status if you break up the contract and leave them for another ISP.
    – NZD
    Commented Aug 9, 2015 at 4:52
  • 2
    Another possibility is your browser. The author of this article had the same issue using Google Chrome and fixed it by using a different browser. The advice given in this D-Link post also suggest that Google Chrome is the culprit.
    – NZD
    Commented Aug 9, 2015 at 4:57
  • @user2824371, did you also try to unzip using 7-Zip?
    – Arjan
    Commented Aug 17, 2015 at 10:33
  • @Arjan No, I will try but I don't think it is the solution because the website provides uncompressed IMG files and they did not work too. Commented Aug 19, 2015 at 12:39

As that desriptions asks you to obtain an updated software image from your ISP it looks like your router is "branded" by the ISP. In that case even a valid firmware update from the original vendor may be considered invalid by the current (branded, non-vendor) firmware. Maybe you should actually follow those directions and check with your ISP for updated firmware.

  • You are right, I bought my router from an ISP and the router comes with their own firmware. Now, I need to change my ISP because their prices are very high (expensive). I have payed the total price for my router and I have the right to use it with any ISP. It is my own router. So why have I to buy a new router from the new ISP ? Would you tell me how to setup the vendor software, please ? Commented Aug 9, 2015 at 0:58
  • @user2824371 Check the contract you signed with your ISP. Just because you effectively paid for the router over time, doesn't automatically "give you the right" to anything. Your contract should spell out exactly what your rights are, including who the router belongs to and any conditions/limitations like being locked in. If the contract says "you own the router", by all means hack away. If the contract says "we own the router" then, um, I wouldn't hack it ;-)
    – misha256
    Commented Aug 19, 2015 at 1:47
  • @misha256 Well, the contract does not say anything about the router :) it says about internet speed and some other details. In my country, It is known that you have two option for having a router. The First one is that you can rent a router and you pay monthly. The second option is you can buy a router from a shop or from an ISP. and I was mistaken to buy a router from ISP because they locked it. Commented Aug 19, 2015 at 12:47

Its because the firmware u downloaded is for aa diffferent hardware revision. Ur hardware version, not just the model no, will be mentioned in the label beneath. Download firmware for that specific hardware type.

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