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Initializes the ethernet library and network settings.


Ethernet.begin(mac, ip);
Ethernet.begin(mac, ip, gateway);
Ethernet.begin(mac, ip, gateway, subnet);


mac: the MAC (Media access control) address for the device (array of 6 bytes). this is the Ethernet hardware address of your shield. Newer Arduino Ethernet Shields include a sticker with the device's MAC address. For older shields, choose your own.

ip: the IP address of the device (array of 4 bytes)

gateway: the IP address of the network gateway (array of 4 bytes). optional: defaults to the device IP address with the last octet set to 1

subnet: the subnet mask of the network (array of 4 bytes). optional: defaults to




#include <Ethernet.h>

// the media access control (ethernet hardware) address for the shield:
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };  
//the IP address for the shield:
byte ip[] = { 10, 0, 0, 177 };    

void setup()
  Ethernet.begin(mac, ip);

void loop () {}

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