I am trying to send UDP packet to my server 10.20.1.2 with port number 20000. I have implemented UDP client on PC and when i send data using sendto API , at the same time i monitor data on wireshark wireshark shows it as an ARP packet.
18967 5440.858646 PcsCompu_ef:b4:89 Broadcast ARP 42 Who has 10.20.1.2? Tell 192.168.1.70
192.168.1.70 is my machine ip where UDP client is running.
I am not sure how UDP packet is getting converted into ARP packet ?
I understand ARP is for finding MAC address of target node but here i already know MAC address of target device , How can i add it in my udp client so it directly starts UDP communication . My target device is one embedded camera , i am not expecting it to reply on ARP request so i want to prevent sending ARP request.
Below is my UDP client code :
Any inputs are highly appreciated. Thanks in advance.
/*
Simple udp client
*/
#include<stdio.h> //printf
#include<string.h> //memset
#include<stdlib.h> //exit(0);
#include<arpa/inet.h>
#include<sys/socket.h>
#define SERVER "10.20.1.2"
#define PORT 20000 //The port on which to send data
char message[3]={0x00, 0x00 , 0x24};
int main(void)
{
struct sockaddr_in si_other;
int s, i, slen=sizeof(si_other);
int ret;
if ( (s=socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
{
printf("socket failed");
}
memset((char *) &si_other, 0, sizeof(si_other));
si_other.sin_family = AF_INET;
si_other.sin_port = htons(PORT);
if (inet_aton(SERVER , &si_other.sin_addr) == 0)
{
fprintf(stderr, "inet_aton() failed\n");
exit(1);
}
ret = sendto(s, message, sizeof(message) , 0 , (struct sockaddr *) &si_other, slen);
close(s);
return 0;
}
