Arduino: Ethernet UDP Receive Data Switch LED

Code

#include <SPI.h>        
#include <Ethernet.h>
#include <EthernetUdp.h>

const int ledPin = 4; // the pin that the LED is attached to

// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {  
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress ip(192, 168, 0, 3);

unsigned int localPort = 8888;      // local port to listen on

// An EthernetUDP instance to let us send and receive packets over UDP
EthernetUDP Udp;

char packetBuffer[UDP_TX_PACKET_MAX_SIZE]; //buffer to hold incoming packet,

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  // initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);
  while (!Serial)
  {
    ; // wait for serial port to connect. Needed for native USB port only
  }
  // start the Ethernet and UDP:
  Ethernet.begin(mac,ip);
  Udp.begin(localPort);
}

void loop()
{
  int packetSize = Udp.parsePacket();
  if(packetSize)
  {
    Serial.print("Received packet of size ");
    Serial.println(packetSize);
    Serial.print("From ");
    IPAddress remote = Udp.remoteIP();
    for (int i =0; i < 4; i++)
    {
      Serial.print(remote[i], DEC);
      if (i < 3)
      {
        Serial.print(".");
      }
    }
    Serial.print(", port ");
    Serial.println(Udp.remotePort()); 
    
    // read the packet into packetBufffer
    Udp.read(packetBuffer,UDP_TX_PACKET_MAX_SIZE);
    Serial.println("Contents:");
    Serial.println(packetBuffer);
    
    // if it's a capital H (ASCII 72), turn on the LED:
    if (packetBuffer[0] == 'H')
    {
      digitalWrite(ledPin, HIGH);
      Serial.println("LED ON\n");
    }
    // if it's an L (ASCII 76) turn off the LED:
    if (packetBuffer[0] == 'L') {
      digitalWrite(ledPin, LOW);
      Serial.println("LED OFF\n");
    }
  }
}

Client

nc -u 192.168.0.3 8888