I bought an original arduino ethernet shield v2. http://www.sgbotic.com/images/detailed/10/01844-01.jpg
Not knowing that the sticker on the back contained something called a MAC address, I tossed it away.....
At the moment I'm trying to this code
#include <SPI.h>
#include <Ethernet.h>
// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network.
// gateway and subnet are optional:
byte mac[] = { 0xA1, 0xA2, 0xD3, 0xC3, 0xF1, 0x2A };
IPAddress ip(192, 168, 1, 118);
IPAddress gateway(192, 168, 1, 1);
IPAddress subnet(255, 255, 255, 0);
// telnet defaults to port 23
EthernetServer server(23);
boolean gotAMessage = false; // whether or not you got a message from the client yet
void setup() {
 // Open serial communications and wait for port to open:
 Serial.begin(9600);
 // start the Ethernet connection:
 Serial.println("Trying to get an IP address using DHCP");
 if (Ethernet.begin(mac) == 0) {
  Serial.println("Failed to configure Ethernet using DHCP");
  // initialize the ethernet device not using DHCP:
  Ethernet.begin(mac, ip, gateway, subnet);
 }
 // print your local IP address:
 Serial.print("My IP address: ");
 ip = Ethernet.localIP();
 for (byte thisByte = 0; thisByte < 4; thisByte++) {
  // print the value of each byte of the IP address:
  Serial.print(ip[thisByte], DEC);
  Serial.print(".");
 }
 Serial.println();
 // start listening for clients
 server.begin();
}
void loop()
{
 // wait for a new client:
 EthernetClient client = server.available();
 // when the client sends the first byte, say hello:
 if (client) {
  if (!gotAMessage) {
   Serial.println("We have a new client");
   client.println("Hello, client!");
   gotAMessage = true;
  }
  // read the bytes incoming from the client:
  char thisChar = client.read();
  // echo the bytes back to the client:
  server.write(thisChar);
  // echo the bytes to the server as well:
  Serial.print(thisChar);
 }
}
I have tried several MAC adresses, from example sketches, from whatever I could find. The current one in the code is a random one.
The arduino never gets past the setup code, I have enclosed a screenshot of the output
(COM output.png).
My first question: Do I have to use the MAC address of the lost sticker persé or can I assign and use other random MAC-adresses as well? I read that this address was hardwired into the shield.
I can propably figure out a for-loop where I test every possible MAC-address.. but 16^12 = 2.8^14 and millis() can get as high 4.29^9 < and this takes 50 days worth of milli seconds. It takes about 300 ms to test a mac address
I also have another question concerning IP-addresses.
I have enclosed another screenshot of the IPconfig out in cmd.exe. I know that my subnet mask is 255.255.255.0 and the gateway is indeed 192.168.1.1. But I do not know of what the IPv4-address is. It is 192.168.1.117. When I looked up the Ip adress of my PC on the internet I got an entire other IP-address
question 2: in IPAddress ip() which IP-adresses can I use? do the first 2 numbers have to be 192.168.xxx.xxx or does it not matter?