#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <netinet/in.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>

int
main()
{
	int status = 0;

	int fd = socket(AF_INET, SOCK_STREAM, 0);
	if (fd < 0)
	{
		printf("socket() failed with %d\n", errno);
		return 1;
	}

	status = setgid(1009); // mail group = 1009
	if (status < 0)
	{
		printf("setgid() failed with %d\n", errno);
		return 1;
	}

	status = setgroups(0, 0);
	if (status < 0)
	{
		printf("setgroups() failed with %d\n", errno);
		return 1;
	}

	status = setuid(1008); // exim user = 1008
	if (status < 0)
	{
		printf("setgid() failed with %d\n", errno);
		return 1;
	}

	int fd2 = dup(fd);
	if (fd2 < 0)
	{
		printf("dup() failed with %d\n", errno);
		return 1;
	}

	status = close(fd);
	if (status != 0)
	{
		printf("close(fd) failed with %d\n", errno);
		return 1;
	}

	status = close(fd2);
	if (status != 0)
	{
		printf("close(fd2) failed with %d\n", errno);
		return 1;
	}

	return 0;
}