this is from 2003 and its missing the includes
which are
#include <unistd.h>
#include <sys/stat.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <stdio.h>
Seti@Home exploit by zillion[at]safemode.org (2003/01/07)