WP Fail2Ban

<?php
/*
Plugin Name: WP fail2ban
Plugin URI: https://charles.lecklider.org/wordpress/wp-fail2ban/
Description: Write all login attempts to syslog for integration with fail2ban.
Version: 2.1.0
Author: Charles Lecklider
Author URI: https://charles.lecklider.org/
License: GPL2
*/

/*
    Copyright 2013     Armando Vega
    Copyright 2012-13  Charles Lecklider  (email : wordpress@charles.lecklider.org)

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2, as
    published by the Free Software Foundation.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/


function f2b_openlog()
{
    openlog('wordpress('.$_SERVER['HTTP_HOST'].')',
             LOG_NDELAY|LOG_PID,
             defined(WP_FAIL2BAN_LOG) ? WP_FAIL2BAN_LOG : LOG_AUTH);
}

function f2b_bail()
{
    ob_end_clean();
    header('HTTP/1.0 403 Forbidden');
    header('Content-Type: text/plain');
    exit('Forbidden');
}

function f2b_remote_addr()
{
    if (defined('WP_FAIL2BAN_PROXIES')) {
        if (array_key_exists('HTTP_X_FORWARDED_FOR',$_SERVER)) {
            $ip = ip2long($_SERVER['REMOTE_ADDR']);
            foreach(explode(',',WP_FAIL2BAN_PROXIES) as $proxy) {
                if (2 == count($cidr = explode('/',$proxy))) {
                    $net = ip2long($cidr[0]);
                    $mask = ~ ( (2 ^ (32 - $cidr[1])) - 1 );
                } else {
                    $net = ip2long($proxy);
                    $mask = -1;
                }
                if ($net == $ip & $mask) {
                    return (false===($len = strpos($_SERVER['HTTP_X_FORWARDED_FOR'],',')))
                            ? $_SERVER['HTTP_X_FORWARDED_FOR']
                            : substr($_SERVER['HTTP_X_FORWARDED_FOR'],0,$len);
                }
            }
        }
    }

    return $_SERVER['REMOTE_ADDR'];
}

function f2b_blocked_users($user, $username, $password){
    if (!empty($username) && preg_match('/'.WP_FAIL2BAN_BLOCKED_USERS.'/i', $username)) {
        f2b_openlog();
        syslog(LOG_NOTICE,"Blocked authentication attempt for $username from ".f2b_remote_addr());
        f2b_bail();
    }
    return $user;
}

function f2b_block_user_enumeration($redirect_url, $requested_url){
    if (intval(@$_GET['author'])) {
        f2b_openlog();
        syslog(LOG_NOTICE,'Blocked user enumeration attempt from '.f2b_remote_addr());
        bail();
    }
    return $redirect_url;
}

function f2b_login($user_login, $user){
    f2b_openlog();
    syslog(LOG_INFO,"Accepted password for $user_login from ".f2b_remote_addr());
}

function f2b_login_failed($username){
    f2b_openlog();
    syslog(LOG_NOTICE,"Authentication failure for $username from ".f2b_remote_addr());
}

if (defined('WP_FAIL2BAN_BLOCKED_USERS')) {
    add_action( 'authenticate','f2b_blocked_users',1,3);
}

if (defined('WP_FAIL2BAN_BLOCK_USER_ENUMERATION')) {
    add_filter( 'redirect_canonical','f2b_block_user_enumeration',10,2);
}

add_action( 'wp_login','f2b_login',10,2);
add_action( 'wp_login_failed','f2b_login_failed');