Arduino DDNS (Dynamic DNS)

By on April 8, 2011
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This device captures the IP address of your network and it publish on site All without PC. It allow a remote access to your LAN even if the IP address of the connections changes.
For logistics reasons the provider can not assign a IP fixed for all users, so many users, especially private, work with a dynamic IP or public IP: in practice when they connect modem or router, to their connection is assigned an IP address that, when the connection will’be closed, can be used by other users. This makes impossible to contact a remote computer or device connected to a LAN Internet.

If you want to access to a device connected to your home LAN (so not with static IP) you must use a service like DynDNS, because every time you connect your ISP dynamically assigns a new IP address.

If you don’t want to use the software provided by DynDNS, and then leave the PC switched on continuously, the solution is this project.
Our device queries the site to know the IP currently used for the connection, and then publish your free account to instead of the computer acquired the new IP. Such a device therefore allows to locate a LAN connected to the Internet via a router or modem network.

Our device is essentially a publisher of IP address. Everything is made ​​from a circuit that incorporates an Ethernet interface WIZnet WIZ811MJ, managed by an Atmega328 microcontroller programmed with the Arduino bootloader, so it all works like an Arduino and you can use the Arduino IDE. The Atmega I/O PB2, PB3, PB4 and PB5 are dedicated to dialogue with the Ethernet module and provide a full four-wire SPI bus. The microcontroller is programmed using the special interface TTL / USB from SparkFun.
The main program sends the request to the IP address site. Now prepare the process of submitting to the site, which provides for the opening of a session onthe web page on, where will send data strings containing user name and password, thena string containing the Current IP connection. Cyclically
the microcontroller check the IP to see if the address is changed, then, if it’s true, sends the new IP to

We use a dedicated circuit but the project can be replicated using an Arduino UNO and a Ethernet Shield.

Sketch Code for Arduino DDNS (Dynamic DNS)


Download ZIP File

Download the DDNS sketch for Arduino


About Boris Landoni

Boris Landoni is the technical manager of Skilled in the GSM field, embraces the Open Source philosophy and its projects are available to the community.


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  6. Dave

    April 14, 2011 at 3:16 PM

    Great project! What are your values for C5, C6, & C7? I don’t see them listed in the BOM. Same with Q1 though I imagine that is the standard 16MHz crystal oscillator.


  7. Boris Landoni

    April 15, 2011 at 9:11 AM

    Ops… :-)
    I add the components.

  8. Xiszone

    April 20, 2011 at 8:16 AM

    It is a very nice project and exactly what i need.
    It is possible to buy the assembled bord from you?

  9. Boris Landoni

    April 20, 2011 at 8:20 AM

    Hi, we can sell only
    U1: WIZNET
    U2: ATMEGA328P (with Arduino bootloader)
    We haven’t the PCB.

  10. dmsherazi

    January 18, 2012 at 7:57 AM

    HI , Nice work , I wanted to implement the dyndns in my project, but i am not fimilair with aurduinos, can u please let me know how would i update my ip address on dyndns using AT commands . I know i have to send

    but how to do that in AT commands i am usnig the same sim900

  11. Boris Landoni

    January 18, 2012 at 9:45 AM

    I suggest you to study this firmware
    You have to connect to the site adding the parameters.

  12. dmsherazi

    January 23, 2012 at 7:56 AM

    HI , thanks for ur prompt reply …

    I checked dyndns support and also the firmware and then connected to the

    and sent this data

    GET /nic/update? HTTP/1.0
    Authorization: Basic a2lxxxxxxxxxxxxxx3M=
    User-Agent: kindows- 12hh- 1.1

    but i get badagent in responce when i connect to port 8245 , if i conncet to port 80 i get no reponse!!

  13. Boris Landoni

    January 23, 2012 at 8:49 AM

    Hi, Try to post your problem on facebook

  14. dmsherazi

    February 12, 2012 at 8:19 AM

    @ BORIS

    hi its dm sherazi here, actually i got the problem solved the problem was with the hyperterminal , i used docklight and it worked well, and then when i programmed my mcu its still working great .

  15. Boris Landoni

    February 13, 2012 at 6:34 PM

    hi dmsherazi, this is a good news. ;-)

  16. Snooper1

    June 16, 2012 at 12:00 AM

    I like your dyn DDNS project. I’m having issues trying to use IDE 1.01

    I have a Arduino UNO V3

    And a Arduino Mega V3

    Both use the Arduino Ethernet shield

    What Arduino build did you use?

    Can you help to update it to the latest Arduino IDE?

  17. clayzz jr

    July 19, 2015 at 7:03 AM

    Hello.. i have a problem..
    When the first run of program.. it works fine and update my ip to dyn.
    When i connect to second time after 30 sec .. it just connect and disconnecting.. and i must reset arduino to update again.. any help ?

  18. Anil

    February 26, 2017 at 3:32 AM

    Doesn’t the router have to do the DDNS? Or is the Arduino here acting as the router? If my router has DDNS, I will simply use that and NAT the Arduino’s IP.

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