Socket Creation Error in Linux but not MacOS - c

Question

I have the following program where I am attempting to re-create ping. This works great when run in my macOS dev environment, but when running in my prod Linux environment the socket fails to get created. I can't figure out why. In addition, any way to resolve this so it works on Linux would be great.
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
/* Calculate ICMP checksum */
uint16_t ip_checksum(void *icmp_header, int size_of_header){
unsigned short *buffer = icmp_header;
unsigned int sum = 0;
uint16_t result;
for(sum=0;size_of_header > 1; size_of_header -=2){
sum += *buffer++;
}
if(size_of_header == 1){
sum += *(unsigned char*)buffer;
}
sum = (sum >> 16) + (sum & 0xffff);
result = ~sum;
return result;
}
int main(int argc, char const *argv[]){
char ip[20]; /* Define variable to hold user entered IP address*/
const int icmp_size=8; /* Size of icmp header */
struct sockaddr_in toSendTo; /* Set sockaddr_in struct */
/* Create ICMP header */
struct icmp_header{
unsigned char icmph_type;
unsigned char icmph_code;
uint16_t icmph_checksum;
unsigned short int icmph_ident;
unsigned short int icmph_seqnum;
} icmp_header;
/* Get user to input IP address */
printf("Please enter an IP address: ");
fgets(ip, sizeof(ip), stdin);
/* Loop to send 3 pings requests */
for(int i = 0; i < 3; i++){
icmp_header.icmph_type = 8; /* Set ICMP type to 8 for sending ICMP request */
icmp_header.icmph_code = 0; /* Set ICMP code to 0 for sending ICMP request */
icmp_header.icmph_checksum = 0; /* Initializee checksum to 0 */
icmp_header.icmph_seqnum = i*20; /* Arbitrary sequence number */
icmp_header.icmph_ident = i+50; /* Arbitrary id */
icmp_header.icmph_checksum = ip_checksum(&icmp_header,icmp_size); /* Calculate checksum */
/* Set transport IP in sockaddr struct */
if (inet_addr(ip) == -1){
printf("Error, invalid IP address\n");
exit(1);
}else{
toSendTo.sin_addr.s_addr = inet_addr(ip);
}
/* Create socket */
int soc = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
/* Check if creation of socket throws an error */
if(soc == -1){
printf("Error creating socket\n");
exit(1);
}
/* Send ICMP ping request */
int send = sendto(soc, &icmp_header, icmp_size, 0, (struct sockaddr *)&toSendTo, sizeof(toSendTo));
/* Check if sending ICMP request throws an error */
if (send < 0){
printf("Error sending ping(%d).\n", i+1);
exit(1);
}else{
printf("\nICMP Echo Request(%d) sent to %s", i+1,ip);
}
unsigned int response_address_size; /* Variable for size of response packet */
char response_buffer[50]; /* Buffer for content of response */
struct sockaddr response_address; /* Struct to hold response address */
/* Struct to hold ICMP response header information */
typedef struct icmp_resp{
unsigned char icmph_type;
unsigned char icmph_code;
uint16_t icmph_checksum;
unsigned short int icmph_ident;
unsigned short int icmph_seqnum;
} icmp_r;
/* Receive ICMP response */
int resp = recvfrom(soc, response_buffer, sizeof(response_buffer), 0, &response_address, &response_address_size);
/* Check if receiving response throws an error */
if (resp < 0){
printf("Error receiving response (%d)\n",i+1);
exit(1);
}
icmp_r* echo_response;
echo_response = (icmp_r *)&response_buffer[20];
/* Determine if Destination Unreachable is response */
if(echo_response->icmph_type == 3 && echo_response->icmph_code == 0){
printf("Destination Unreachable...\n");
}else{
/* Print ICMP response information */
printf("ICMP Response(%d) : type=%d,code=%d,checksum=%x, ident=%d, seq=%d\n\n", i+1,
echo_response->icmph_type,
echo_response->icmph_code,
ntohs(echo_response->icmph_checksum),
echo_response->icmph_ident,
echo_response->icmph_seqnum);
}
/* Close Socket */
close(soc);
}
}
Here is my output when run in Linux:
Please enter an IP address: 8.8.8.8
Error creating socket

Answer 1

You have to set ping_group_range with sysctl like in the example below for specifying the groups who can create IPPROTO_ICMP sockets.
sysctl -w net.ipv4.ping_group_range="gid gid"
From the documentation:
ping_group_range (two integers; default: see below; since Linux
2.6.39)
Range of the group IDs (minimum and maximum group IDs,
inclusive) that are allowed to create ICMP Echo sockets.
The default is "1 0", which means no group is allowed to
create ICMP Echo sockets.
Edit
The socket type has to be SOCK_DGRAM instead of SOCK_RAW in int soc = socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP); and you also need to define toSendTo.sin_family = AF_INET;.