Matt Keys

Anti-Spam solutions that require your users to fill out captcha’s are frustrating for actual humans, and not that great at stopping bots.
This solution works automatically without any user configuration, and puts no additional burden on your users. After activation this plugin will go to work stopping: comment spam, spam bot registration, and bbPress spam.
Key features:
<ul>
<li>Fully compatible with wordpress caching plugins or even more advanced server level caching solutions (like WP Engine uses).</li>
<li>Utilizes randomly generated and rotating token field name and token value, which stops more clever bots that might try caching the ‘solved’ field.</li>
<li>Anti-spam field is randomly placed within the form on page load to make it difficult for spammers to target the field.</li>
<li>Developer friendly with filters and actions</li>
<li>Lightweight, clean, and efficient solution to comment, registration, and bbPress spam</li>
<li>Uses native JavaScript to avoid jQuery dependancies</li>
</ul>
Requires JavaScript be enabled in client browser (Users will see a warning if JavaScript is disabled)

Advanced Invisible Anti-Spam

Block bots without annoying captchas. Cache friendly solution with rotating keys! Blocks comment, registration, and bbpress spam. Activate and done!

IP-to-Country is a plugin which doesn’t provide any output to users, but which 
may be used by plugin authors to quickly and easily find, in which country an 
IP address is located.
To do so the plugin uses data files from either http://ip-to-country.webhosting.info 
(IPv4 only) or http://software77.net/geo-ip/ (both IPv4 and IPv6). 
Other sources are possible as long as they have the same format: CSV file, 
fields enclosed with quotes (“) and separated with comma (,), lines ending 
with LF (\n). Five columns:
<ul>
<li>Lower bound of an IP range.</li>
<li>Upper bound of an IP range. Both are represented as one 32-bit integer number, 
such as you can get by using funtion ip2long().</li>
<li>2-character country code</li>
<li>3-character country code</li>
<li>Country name</li>
</ul>
Note: In order to import IPv6 addresses, IPv4 must be imported first. The 
reason is, IPv6 database does not carry the full country information with 
it, while the IPv4 database does.
Operations:
<ul>
<li>
To detect if IP-to-Country plugin is installed:
$ip2c_available = class_exists(‘PepakIpToCountry’);
</li>
<li>
To find information about a numeric IP address:
$country = PepakIpToCountry::IP_to_Country_Full(‘8.8.8.8’); 
 // returns ‘UNITED STATES’ 
 $country = PepakIpToCountry::IP_to_Country(‘8.8.8.8’); 
 $country = PepakIpToCountry::IP_to_Country_XX(‘8.8.8.8’); 
 // both return ‘US’ 
 $country = PepakIpToCountry::IP_to_Country_XXX(‘8.8.8.8’); 
 // returns ‘USA’ 
 $country = PepakIpToCountry::IP_to_Country_Info(‘8.8.8.8’); 
 // returns Array(‘iso_name’=>’UNITED STATES’, ‘iso_code2’=>’US’, ‘iso_code3’=>’USA’) 
$image = PepakIpToCountry::IP_to_Country_Flag(‘8.8.8.8’); 
// returns ”
You may leave the IP address empty; in that case, IP address of currently 
active user is used instead.
Note: All requests are cached, so there shouldn’t be a noticeable difference 
between reading IP_to_Country_Info and reading all three pieces of information 
separately using the _Full, _XX and _XXX functions.
</li>
<li>
To interface your plugin’s tables to IP-to-Country plugin’s tables within SQL, 
a function <code>Subselect</code> is published:
$subselect = PepakIpToCountry::Subselect($ip, $countryfield);
<ul>
<li><code>$ip</code> is a field that contains IP address in the form of one 32bit number, e.g.</li>
</ul>
<ol>
<li>If you store IP addresses in the usual form of four dot-separated 
numbers (‘127.0.0.1’), you can use MySQL’s function INET_ATON: 
$ip = ‘INET_ATON(my_ip_address_field)’; 
It is strongly recommended to use qualified field names (with tablename in 
front, separated by a dot): 
$ip = ‘INET_ATON(banlist.ip_address)’;</li>
</ol>
<ul>
<li><code>$countryfield</code> is the field you want returned. It can be one of the following: 
iso_name – returns the same string as PepakIpToCountry::IP_to_Country_Full(…) 
iso_code2 – returns the same string as PepakIpToCountry::IP_to_Country_XX(…) 
iso_code3 – returns the same string as PepakIpToCountry::IP_to_Country_XX(…)</li>
</ul>
Note: No checking or validation is done on either of these parameters. It is assumed 
they are field names, NOT strings. DO NOT EVER USE VALUES THAT YOUR USERS CAN 
INFLUENCE! This is important! If you let users supply arguments to Subselect(), you 
are letting them to do whatever they like with your database!
This function only works with IPv4 addresses.
Example usage:
if (class_exists(‘PepakIpToCountry’)) 
 $field = PepakIpToCountry(“INET_ATON(b.ip_addr)”, ‘iso_code2’); 
 else 
 $field = ‘NULL’; 
 $sql = “SELECT b.*, ${field} country_code FROM ${wpdb->prefix}banlist b WHERE …”;
</li>
</ul>
Note: This plugin requires PHP5. If you want it to work with ZIP files 
(e.g. for updating IP-country info from the default location), your PHP 
must have extension php_zip enabled.

IP-to-Country

Provide a simple interface for plugin authors to determine, in which country an IP is located.

Advanced Invisible Anti-Spam vs IP-to-Country