3421	stream	tcp	nowait	nobody	/usr/local/bin/black_hole_http_server.pl	noproxy

kill -HUP <PID of inetd>

#!/usr/bin/perl
# Time-stamp: "2002-02-22 14:01:52 MST"
#
# Black-hole proxy server.  sburke@cpan.org
#

use strict;
use IO::Socket qw(: DEFAULT :crlf);
use constant MY_PORT => 9123;
use constant DEBUG => 0;

my $image_type = 'image/gif';
my $image = "$ENV{'HOME'}/public_html/null.gif";

{
    if(PrivoxyWindowOpen(IN, "<$image")) {
	binmode(IN);
	local $/;
	$image = join '',
	  "HTTP/1.0 200 OK", CRLF,
	  "Content-Type: ", $image_type, CRLF, CRLF,
	  <IN>;
	close(IN);
    } else {
        # Default image:
	$image = join '',
	  "HTTP/1.0 200 OK", CRLF,
	  "Content-Type: ", $image_type, CRLF, CRLF,
	  # 8x8 image: box with a border.
          "\x47\x49\x46\x38\x37\x61\x08\x00\x08\x00\xb3",
          "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
          "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
          "\x40\x40\x40", # Inside box color
          "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
          "\x00\x00\x00\x00\x00\x00\x00\x00\x00",
          "\x00\x00\x00", # Outside border color
          # Actual gif data:
          "\x2c\x00\x00\x00\x00\x08\x00\x08\x00\x00\x04\x0e\xf0\xc9\x49",
          "\xeb\x3c\xf8\xd0\xac\x6f\xde\x9f\x25\x52\x11\x00\x3b",
        ;
    }
}
#-----------------------------------------------------------------------------

my $quit = 0;
$SIG{'INT'} = sub {$quit = 1};

my $sock = IO::Socket::INET->new(
  Listen => 20,        LocalPort => shift(@ARGV)|| MY_PORT,
  Timeout => 60 * 60,  Reuse => 1,
) or die "Can't create listening socket: $!\n";

DEBUG and warn "Waiting for connections...\n";

my($session, $peer, $port);
while(!$quit) {
  next unless my $session = $sock->accept;
  if(DEBUG) {
    $peer = gethostbyaddr($session->peeraddr, AF_INET)
     || $session->peerhost;
    $port = $session->peerport;
    warn "Connection from [$peer,$port] at ", scalar(localtime), "\n";
  }

  #select($session);
  #++$|;
  #select(STDOUT);
  
  print $session $image;
  close($session);
  DEBUG and print " (Closed)\n";
}

DEBUG and print STDERR "Byebye\n";
close($sock);
exit 0;

//  b. A simple, blackhole server
//
//      When needed, I run a simple "server" at port 3421 that denies
//      all requests.  Some options you can use for this:
//
//      - On Windows, you can try Larry Wang's black-hole proxy program:
//
//          http://leisuresuit10.tripod.com/BlackHoleProxy/
//
//        I can not vouch that his binaries are virus free, but he does
//        offer the source code.
//
//      - I use this shell script on UNIX; it is invoked via inetd.
//        /usr/local/lib/noproxy:
//
//          #!/bin/sh
//          read a
//          read b
//          echo HTTP/1.0 501 No Ads Accepted
//          echo ""
//          exit
//
//        Add this line to inetd.conf ('kill -HUP' inetd afterwards):
//
//          3421 stream tcp nowait nobody /usr/local/lib/noproxy noproxy
//
//        This simple script doesn't work on Linux because of the
//        (IMHO) broken way it's TCP stack works.  See the bottom of
//        http://www.schooner.com/~loverso/no-ads/ for a complete copy
//        of the `noproxy' shell script.
//
//        If always exec'ing a shell was expensive on your computer
//        (it isn't on mine), then you could use a "wait"-style Perl
//        script that would accept() incoming connections.
//
//      - Sean Burke has a black-hole proxy written in Perl script:
//
//        http://www.speech.cs.cmu.edu/~sburke...http_server.pl
//        (This is a standalone server, not run from inetd).

// ***
// *** Update the next line with the correct hostname: port
// *** of your blackhole proxy server, if needed.
// ***
// *** (If you use IE, this is already fine)
// ***
// var blackhole = "PROXY 127.0.0.1:3421";    // Original entry
 var blackhole = "PROXY 127.0.0.1:3421/usr/local/bin/blackhole_proxy.pl";