Just to add some code that can be used as is, I have written a subclass for Apache::AntiSpam by Tatsuhiko Miyagawa, that implements this method. The code is not perfect but working. I also sended this to Tatsuhiko and asked him to bundle this with his modules.
package Apache::AntiSpam::SpamTrap;
use strict;
use vars qw($VERSION);
$VERSION = '0.01';
use Apache::AntiSpam;
use Apache::Constants qw(:common);
use base qw(Apache::AntiSpam);
use Crypt::Blowfish;
sub antispamize {
my($class, $email, $orig) = @_;
# this seems not very efficient
my $r = Apache->request();
# better error handling?
my $key = $r->dir_config('Key') || return SERVER_ERROR;
my $ip = $r->get_remote_host || return SERVER_ERROR;
my $time = time;
my $string = spamtrap_encode($ip, $time, $key);
$orig =~ s/\@/-$string\@/;
return $orig;
}
sub spamtrap_encode
{
my ($ip, $time, $key) = @_;
return unless $key;
return unless $time > 0;
return unless $ip =~ /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/o;
my $inkey = pack("H16", $key);
my $plaintext = join("", map { chr } split (/\./, $ip)) . pack("L"
+, $time);
my $cipher = new Crypt::Blowfish $inkey;
my $string = unpack("H*", $cipher->encrypt($plaintext));
return $string;
}
1;
__END__
=head1 NAME
Apache::AntiSpam::SpamTrap - Add SpamTrap suffix to local-part in Emai
+l
=head1 SYNOPSIS
# in httpd.conf
<Location /antispam>
SetHandler perl-script
PerlAddVar Key 0123456789ABCDEF
PerlHandler Apache::AntiSpam::SpamTrap
</Location>
# filter aware
PerlModule Apache::Filter
SetHandler perl-script
PerlSetVar Filter On
PerlHandler Apache::RegistryFilter Apache::AntiSpam::SpamTrap Apache
+::Compress
=head1 DESCRIPTION
Apache::AntiSpam::SpamTrap is a subclass of Apache::AntiSpam, filter
module to prevent e-mail addresses exposed as is on web pages. This
module adds a Blowfish encrypted string suffix to the local-part of
e-mail addresses. This string contains a timestamp and the IP address
of the remote host. This enables you to identify a spammer's address
harvester by its IP address and take steps to prosecute him.
The encryption prevents faking and may help in a prosecuting attemp.
For example, C<apleiner@cpan.org> will be filtered to
C<apleiner-78c1ed6da0322b3a@cpan.org>.
This module is Filter aware, meaning that it can work within
Apache::Filter framework without modification.
You need to give the Blowfish key in your Apache configuration file.
To decode a received mail's SpamTrap string use the following function
+:
sub spamtrap_decode
{
my ($string, $key) = @_;
return unless $key;
return unless $string =~ /[0-9a-f]{16}/o;
my $inkey = pack("H16", $key);
use Crypt::Blowfish;
my $cipher = new Crypt::Blowfish $inkey;
my $plaintext = $cipher->decrypt(pack("H*", $string));
my $time = unpack("L", substr($plaintext, 4, 4));
my $ip = join(".", map { ord } split //, substr($plaintext, 0, 4
+));
return wantarray ? ($ip, $time) : "$ip $time";
}
=head1 TODO
=over 4
=item *
should make local address part be configured.
=back
=head1 AUTHOR
Alex Pleiner <alex@zeitform.de> - zeitform Internet Dienste 2003
This work is based on the Apache::AntiSpam::* modules provided by
Tatsuhiko Miyagawa <miyagawa@bulknews.net>. The idea is taken from
Daniel A. Rehbein (http://daniel.rehbein.net/).
This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.
=head1 SEE ALSO
L<Apache::AntiSpam>
=cut
alex pleiner <alex@zeitform.de>
zeitform Internet Dienste | 