with arduino ethernet shield (board)
Getting
Started with the Arduino Ethernet Shield
web server -- device answers a HTTP request. Use your
browser to ethernet shield IP address, arduino will response with values
from analog pins.
https://www.arduino.cc/en/Tutorial/WebServer
chat server -- distribute any incoming messages to all connected clients.
Open a terminal, Telnet to device IP address and type. Will see client's
input in the serial monitor. https://www.arduino.cc/en/Tutorial/ChatServer