Подсчет числа возможных открытых TCP-портов

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

#include <stdio.h>

int main() {
  int port;
//  int maxport = 10000000;
  int maxport = 65535;
  int count = 0;
  for (port = maxport; port > -1; port--) {
    int sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock < 0) continue;
    const int on = 1;
    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0) continue;
    struct sockaddr_in serv_addr;
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(port);
    if (bind(sock, (struct sockaddr *)&serv_addr, sizeof(struct sockaddr_in)) < 0) continue;
    count++;
    close(sock);
  }
  printf("count = %d\n", count);
}