As suggested by a monk a few days past, to help put a stop to these bandwidth whores that are scraping my site for images, I was told to look at modperl http://www.modperl.com/book/chapters/ch6.html#Blocking_Greedy_Clients.
The code below is what they say I should use. I understand the code, but not where to use it. This is a module, is it not? Do I just save this as a .pm and use it in my .htaccess file? Or how do I go about getting this code to work?
package Apache::SpeedLimit;
# file: Apache/SpeedLimit.pm
use strict;
use Apache::Constants qw(:common);
use Apache::Log ();
use IPC::Shareable ();
use vars qw(%DB);
sub handler {
my $r = shift;
return DECLINED unless $r->is_main; # don't handle sub-requests
my $speed_limit = $r->dir_config('SpeedLimit') || 10; # Accesses
+per minute
my $samples = $r->dir_config('SpeedSamples') || 10; # Sampling
+threshold (hits)
my $forgive = $r->dir_config('SpeedForgive') || 20; # Forgive a
+fter this period (minutes)
my $expire = $r->dir_config('SpeedExpire') || 40; # Expire unus
+ed
# records from memory after this period (mi
+nutes)
my $content_type = $r->lookup_uri($r->uri)->content_type;
return OK if $content_type =~ m:^image/:i; # ignore images
tie %DB, 'IPC::Shareable', 'SPLM', {create => 1, mode => 0644}
unless defined %DB;
my($ip, $agent) = ($r->connection->remote_ip, $r->header_in('User
+-Agent'));
my $id = "$ip:$agent";
my $now = time()/60; # minutes since the epoch
# lock the shared memory while we work with it
tied(%DB)->shlock;
my($first, $last, $hits, $locked) = split ' ', $DB{$id};
my $result = OK;
my $l = $r->server->log;
CASE:
{
unless ($first) { # we're seeing this client for the first tim
+e
$l->debug("First request from $ip. Initializing speed cou
+nter.");
$first = $last = $now;
$hits = $locked = 0;
last CASE;
}
if ($now - $last > $forgive) { # beyond the grace period. Tre
+at like first
$l->debug("$ip beyond grace period. Reinitializing speed
+counter.");
$last = $first = $now;
$hits = $locked = 0;
last CASE;
}
# update the values now
$last = $now; $hits++;
if ($hits < $samples) {
$l->debug("$ip not enough samples to calculate speed.");
last CASE;
}
if ($locked) { # already locked out, so forbid access
$l->debug("$ip locked");
$result = FORBIDDEN;
last CASE;
}
my $interval = $now - $first;
$l->debug("$ip speed = ", $hits/$interval);
if ($hits/$interval > $speed_limit) {
$l->debug("$ip exceeded speed limit. Blocking.");
$locked = 1;
$result = FORBIDDEN;
last CASE;
}
}
$r->log_reason("Client exceeded speed limit.", $r->filename)
if $result == FORBIDDEN;
$DB{$id} = join " ", $first, $now, $hits, $locked;
foreach my $key (keys %DB) {
my ($first, $last, $hits, $locked) = split(' ', $DB{$key});
if ($now - $last > $expire) {
delete $DB{$key};
}
}
tied(%DB)->shunlock;
return $result;
}
1;
__END__
