udpClient.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>

void main(int argc, char **argv){
  if(argc != 2){
    printf("Usage: %s <port>\n", argv[0]);
    exit(0);
  }

  int port = atoi(argv[1]);
  int sockfd;
  struct sockaddr_in serverAddr;
  char buffer[1024];
  socklen_t addr_size;

  sockfd = socket(PF_INET, SOCK_DGRAM, 0);
  memset(&serverAddr, '\0', sizeof(serverAddr));

  serverAddr.sin_family = AF_INET;
  serverAddr.sin_port = htons(port);
  serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");

  strcpy(buffer, "Hello Server\n");
  sendto(sockfd, buffer, 1024, 0, (struct sockaddr*)&serverAddr, sizeof(serverAddr));
  printf("[+]Data Send: %s", buffer);

}