Thread: Problems with setsockopt function (linux)

I'm trying to research more about the code I've seen a few days ago,it's include using a function called SetSockOpt with the swich

Code:

PT_SO_SET_REPLACE

and in the api level

Code:

SOL_IP

.
Unfortunately, I could not find any documentation on what exactly this switch should do (and it may be the source of the problem)

So i tried to run the code setsockopt with the flag IPT_SO_SET_REPLACE but i keep getting the wired error from errno

Code:

Protocol not available

this is the code:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sched.h>
#include <linux/sched.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <netinet/in.h>
#include <net/if.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <fcntl.h>


int netfilter_setsockopt(void *p) {
    int sock;
    int ret;
    void *data;
    size_t size;
    struct ipt_replace *repl;


    sock = socket(PF_INET, SOCK_RAW, IPPROTO_RAW);


    if (sock == -1) {
            perror("socket");
            return -1;
    }


    size = sizeof(struct ipt_replace);


    data = malloc(size);


    if (data == NULL) {
        perror("malloc");
        return -1;
    }


    memset(data, 0, size);


    repl = (struct ipt_replace *) data;


    repl->num_counters = 0x1;
    repl->size = 0xffffffff;
    repl->valid_hooks = 0x1;
    repl->num_entries = 0x1;
       
        //this function alwaise return -1
    ret = setsockopt(sock, SOL_IP, IPT_SO_SET_REPLACE, (void *) data, size);


    printf("done %d\n", ret);
        
        //errno say "Protocol not available"
        perror("error cose: ");


    return 0;
}


int main(void) {
    void *stack;
    int ret;


    ret = unshare(CLONE_NEWUSER);


    if (ret == -1) {
        perror("unshare");
        return -1;
    }


    stack = (void *) malloc(65536);


    if (stack == NULL) {
        perror("malloc");
        return -1;
    }


    clone(netfilter_setsockopt, stack + 65536, CLONE_NEWNET, NULL);


    sleep(1);


    return 0;
}

* i compile the code with

Code:

gcc -m32 code.c -o code

and try also with

Code:

gcc code.c -o code

with both of them i get a few warning (nothing series) but the code got compiled ,and in both the error is the same
* I'm runing linux 32 bit kernel version 4.4.0-21-generic (ubunto 16.04)

What could be the problem?
How can i fix it and make the code work?
Where i can find more reading materials on setsockopt api level and swiches?

Thank you

This is the error i got (i'm on

Code:

 ubuntu 4.4.0-21 32 bit

):

Code:

warning: implicit declaration of function 'unshare' [-Wimplicit-function-declaration]  ret=unshare(CLONE_NEWUSER);
warning: implicit declaration of function 'clone' [-Wimplicit-function-declaration]     clone(netfilter_setsockopt,stack+65536,CLONE_NEWNET,NULL);

i want to point out that the code compiled the problem is that it return error (when i'm runing the program ) on setsockopt function .

Is this you as well?
c - setsockopt IPT_SO_SET_REPLACE flag return error (linux) - Stack Overflow

Yes , thank you for the How to asc q. link