This example connects to a Telnet server using an Ethernet shield. Messages from the server are printed out via the serial port. Messages can be sent to the remote server serially as well. The Serial monitor works well for this purpose.
A telnet server
Alternatively, Processing has a ChatServer example that works well for this purpose
The Ethernet shield allows you to connect a WIZNet Ethernet controller to the Arduino boards via the SPI bus. It uses the ICSP header pins and pin 10 as chip select for the SPI connection to the Ethernet controller chip. Later models of the Ethernet shield also have an SD Card on board. Digital pin 4 is used to control the chip select pin on the SD card.
The shield should be connected to a network with an Ethernet cable. You will need to change the network settings in the program to correspond to your network.
In the above image, the Arduino board would be stacked below the Ethernet shield.
Last revision 2018/09/07 by SM