Picture of Arduino Ethernet Shield Tutorial
The Arduino Ethernet Shield allows you to easily connect your Arduino to the internet. This shield enables your Arduino to send and receive data from anywhere in the world with an internet connection. You can use it to do fun stuff like control robots remotely from a website, or ring a bell every time you get a new twitter message. This shield opens up endless amounts of possibility by allowing you to connect your project to the internet in no-time flat.

Step 1: Setup

Picture of Setup
Setting it up is as simple as plugging the header pins from the shield into your Arduino.

Note that the Ethernet Shield sold at Radioshack is online compatible with Arduino Uno Rev. 3 boards (or later). It has too many pins to plug into earlier version Arduino boards.
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GayanH9 days ago

Can we use wifi insted of CAT5 cables for wireless communication?

hiker_alan1 month ago

looks like photo is not correct. Looks like the black wire of switch is connected to ground, not 5V. Hooked up to 5V instead and it seems to be working. Get DARK/LIGHT on website [firefox]

makeosaurus1 month ago

can you use this shield connected to your computers ethranet port

KaushalK2 months ago

I get this message :
Failed to configure Ethernet using DHCP
any idea how to fix this thx ?

ipconfig /all gives me the physical address that i put in mac[].
it also says dhcp enabled : no
even if code is for DHCPaddressPrinter.

in case of ethernet server code :
i cant open my ip address in web browser.
when i ping it says "destination host unreachable".

MalikA52 months ago

please help me, serial monitor can't be open....
it says "Board at COM49 is not available"

animeguard2 months ago

thanks for sharing nice idea

gcharai3 months ago

I get this message :
Failed to configure Ethernet using DHCP
any idea how to fix this thx ?

summervin3 months ago

Hi, thanks for the wonderful walk-through! However, the twitter client doesn't seems to work.. Any idea?

GodoC4 months ago

Thanks ! it worked for me. Just a little reminder : to get the info on your monitor, don't forget to set it to the same baud rate as the one set by the program (ie DhcpAddressePrinter) for the serial connection (check the number XXX in Serial.begin(XXX)). To change the baud rate, you can use the "check list button" at bottom right of the monitor

嘉瑜陳5 months ago

Thanks for the tutorial, but i have a question to the server work example.
If i would like to use other strings other than "$1" and "$2", like "$ledon" for switching on the led connected, what adjustment need to do to the codes.
I find it difficult to solve this problem.

voltman5 months ago

Didn't work with 1.0, but first time with 1.6.1

oregondunerz6 months ago

Let me first start by saying that I am a complete noob when it comes to anything Arduino. My kit hasn't even arrived in the mail yet so please go easy on me. :)

However, I have a question regarding this project. Specifically the RJ45 Ethernet Shield. In your example you are using the RJ45 to interact with the Arduino via a website/internet, is it possible to use the Arduino + Shield to interact with a series of rocker switches via a 8 channel relay board? If so, I was thinking that it would make the installation of my project really clean being able to use the RJ45 cable between my Arduino and the switches that will be located perhaps 10-15 feet away.

Any and all help is appreciated.

cool.honny.56 months ago

This Tutorial is Fantastic and very very very very clear everything.Got this tutorial after 4 days searching on my related topic.

Many Many Thanks Dear.

Excuse me, does anyone know how to access the ethernet shield from the outside of the local network - that is from the internet? I guess the local dynamic IP has to be changed, right..? Where to get that IP?

how to access the ethernet shield from the outside of the local network - that is from the internet?

You need to port forward the IP and port you are using of the ethernet shield to the internet

This website may help: http://portforward.com/

I guess the local dynamic IP has to be changed, right..?

Yes if you are port forwarding the ethernet shield should have a static local IP. You can define the ethernet shield IP in the code.


you can find your DNS servers, gateway, and subnet by typing ipconfig /all in a windows command line.

Make the ip of the ethernet shield any ip not currently used on you network. An easy way do do this is to take IP address listed in ipconfig /all and change the numbers after the last dot to 254 and put that in the arduino code as its IP.

Where to get that IP?

If you mean your public IP you can find that by visiting


Sarmadalabbad6 months ago
Nice thank u
nur.rohmat17 months ago

thanks for your information,


IdeS9 months ago

It's useful thank

midnightcow9 months ago

Nice Tutorial!!

I'm a engineer in WIZnet providing W5100 to the official Arduino Ethernet Shield.

WIZnet made W5500 and WIZ550io/ioShield-A. If you are interested in W5500 and make a tutorial of W5500, I will give a WIZ550io to you free. If you want, feel freely to contact me.

Thank you.

parth_bhat2 years ago
my ethernet shields ic gets hot will u plsplspls help me for that
am using arduino leonardo board
pls help me

I have one of the Non-POE (power Over Ethernet) 5100's, and it does the same to me.. I think it's the 3.3V regulator trying to run the single chip, which is chewing-up massive wattage.. (even if it is being powered from the +5V regulator from the Arduino.) I've often wondered, if I could repower this off the 3.3V off an external power supply, but someone said that's a bad idea, as the back-feed could burn-out the regulator, and other chips switching between the 9 down to 5, and 5 down to 3.3, or even the USB to serial chip.

You need to supply the arduino and the shield with 7 or 7.5 v, you can use a dc-dc power regulator. I use a 12v power suply and a dc to dc regulator, who give me 7.5v and everything is fine.

randofo (author)  parth_bhat2 years ago
Did you do anything to change it, and/or did you plug it in correctly? It sounds like you are shorting something.

Wow! a whole year later? No, It's something about the 3.3 regulator, that is handling a lot of amperage from the 5100.. I thought I saw somewhere on another instructable, someone solved the problem (slightly) by DOUBLING the regulator. (stacking another one on top of the original, so you had 2 in parallel.) http://www.instructables.com/id/Beef-up-your-Arduino-power/

That happens with my wiznet W5100 too. It just happens I think.
antoniol11 year ago

Thanks a lot work at the first run.No problem with me here.

hzv83 years ago
'and open the serial monitor. It should print out the IP address in use.'

This dosen't work...........WTF
randofo (author)  hzv83 years ago
Are you using Arduino 1.0?

i have the same problem, i'm using Arduino 1.0.5 and the serial monitor don't print the IP address

check the baud rate of serial monitor

samething happened to me, had the baud set to 115200, changed it to 9600, and it works

Use DHCPAddressPrint it should work...

rstott21 year ago

This instructable answered questions I couldn't resolve after hours of work! Thanks for taking the time to do it!

AmpOwl1 year ago

Could you make it send emails? I'm thinking of hooking one up to a 3D printer to email you when it finishes a print.

waterlubber2 years ago
What if you don't have access to a router? (e.g apartment building, hotel rooms...) Can I use the ethernet port on my win7 computer?

I have the same problem, I've tried connecting the shield to the router directly and it worked, but I can't do it in my computer. I use Windows Vista, and the cable I'm using is crossed over (with just 4 wires). Do I need to configure something in Windows or what could I do?

Port should handle the cross over internally if its a newer computer if it doesn't you will need a cross over cable.
What is a crossover cable, and do I need one? (If so, why) I have an Atheros AR8132 PCI-E Fast Ethernet Controller and and Atheros AR5B95 Wireless Network Controller.
Well communicating from pc to pc via the rj45 port in the past you would need a cross over cable. Alot of ports on newer computers usually handle this internally. You may need to check the specs for your computer. Please read up on cross over cables. Just look up pc to pc networking via rj45 port. Basically pc to pc networking. The arduino and ethernet shield is basically a computer.
OK, my memory just gave me the memory of hooking up mine with another (it worked) so a Windows 7 computer seems to be compatible. ;P Is it like the serial cables when you have to "cross over" the TX and RX wires? Anyhows, its working. Thanks for the help.
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