I found a reference (
http://www.tenouk.com/Module43a.html
) for using raw sockets to send a simple UDP packet in Linux, but I cannot get it to work on macOS Sierra10.12.1. I've tried a number of different variations, but sendto() always returns
Invalid argument
.
I'd be grateful if you could point out my mistake.
Thanks!
#include <iostream>
#include <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <arpa/inet.h>
#define PCKT_LEN 8192
struct ipheader {
unsigned char iph_ihl:5, iph_ver:4;
unsigned char iph_tos;
unsigned short int iph_len;
unsigned short int iph_ident;
unsigned char iph_flag;
unsigned short int iph_offset;
unsigned char iph_ttl;
unsigned char iph_protocol;
unsigned short int iph_chksum;
unsigned int iph_sourceip;
unsigned int iph_destip;
struct udpheader {
unsigned short int udph_srcport;
unsigned short int udph_destport;
unsigned short int udph_len;
unsigned short int udph_chksum;
unsigned short csum(unsigned short *buf, int nwords)
unsigned long sum;
for(sum=0; nwords>0; nwords--)
sum += *buf++;
sum = (sum >> 16) + (sum &0xffff);
sum += (sum >> 16);
return (unsigned short)(~sum);
int main(int argc, char *argv[])
int sd;
char buffer[PCKT_LEN], *data;
struct ipheader *ip = (struct ipheader *) buffer;
struct udpheader *udp = (struct udpheader *) (buffer + sizeof(struct ipheader));
data = ((char *)udp + sizeof(struct udpheader));
struct sockaddr_in sin, din;
int one = 1;
const int *val = &one;
memset(buffer, 0, PCKT_LEN);
printf("*** start Debug ***\n");
printf("char: %lu\n", sizeof(char));
printf("short: %lu\n", sizeof(short));
printf("unsigned short: %lu\n", sizeof(unsigned short));
printf("int: %lu\n", sizeof(int));
printf("unsigned int: %lu\n", sizeof(unsigned int));
printf("long: %lu\n", sizeof(long));
printf("unsigned long: %lu\n", sizeof(unsigned long));
printf("*** end Debug ***\n");
if(argc != 5)
printf("- Invalid parameters!!!\n");
printf("- Usage %s <source hostname/IP> <source port> <target hostname/IP> <target port>\n", argv[0]);
exit(-1);
int srcPort = atoi(argv[2]);
int destPort = atoi(argv[4]);
char *str_srcIP = argv[1];
char *str_destIP = argv[3];
int srcPort = 23;
int destPort = 23;
char str_srcIP[] = "192.168.1.72";
char str_destIP[] = "192.168.1.73";
sd = socket(PF_INET, SOCK_RAW, IPPROTO_UDP);
if(sd < 0)
perror("socket() error");
exit(-1);
printf("socket() - Using SOCK_RAW socket and UDP protocol is OK.\n");
sin.sin_len = sizeof(sin);
din.sin_len = sizeof(din);
sin.sin_family = AF_INET;
din.sin_family = AF_INET;
sin.sin_port = htons(srcPort);
din.sin_port = htons(destPort);
sin.sin_addr.s_addr = inet_addr(str_srcIP);
din.sin_addr.s_addr = inet_addr(str_destIP);
strcpy(data, "A");
unsigned long payloadSize = sizeof(struct ipheader) + sizeof(struct udpheader) + strlen(data);
ip->iph_ihl = 5;
ip->iph_ver = 4;
ip->iph_tos = 0;
ip->iph_len = payloadSize;
ip->iph_ident = htons(54321);
ip->iph_ttl = 64;
ip->iph_protocol = IPPROTO_UDP;
ip->iph_sourceip = inet_addr(str_srcIP);
ip->iph_destip = inet_addr(str_destIP);
udp->udph_srcport = htons(srcPort);
udp->udph_destport = htons(destPort);
udp->udph_len = htons(sizeof(struct udpheader));
ip->iph_chksum = csum((unsigned short *)buffer, sizeof(struct ipheader) + sizeof(struct udpheader));
if(setsockopt(sd, IPPROTO_IP, IP_HDRINCL, val, sizeof(one)) < 0)
perror("setsockopt() error");
exit(-1);
printf("setsockopt() is OK.\n");
printf("Trying...\n");
printf("Using raw socket and UDP protocol\n");
printf("Using Source IP: %s port: %u, Target IP: %s port: %u.\n", str_srcIP, srcPort, str_destIP, destPort);
std::cout<<"*** start Debug ***"<<std::endl;
std::cout<<"sd: "<<sd<<std::endl;
std::cout<<"Buffer: "<<buffer<<std::endl;
std::cout<<"iph_len: "<<ip->iph_len<<std::endl;
std::cout<<"sin: "<<(struct sockaddr *)&sin<<std::endl;
std::cout<<"sizeof(sin): "<<sizeof(sin)<<std::endl;
std::cout<<"*** end Debug ***"<<std::endl;
int count;
for(count = 1; count <=20; count++)
if(sendto(sd, buffer, ip->iph_len, 0, (struct sockaddr *)&sin, sizeof(sin)) < 0)
perror("sendto() error");
exit(-1);
printf("Count #%u - sendto() is OK.\n", count);
sleep(2);
close(sd);
return 0;
What are you trying to do here? Most folks who want to send UDP use a UDP socket (that is,
AF_INET
or
AF_INET6
with
SOCK_DGRAM
). Why are you trying to send UDP using a raw socket?
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Apple Developer Relations, Developer Technical Support, Core OS/Hardware
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