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Workaround for Comcast blocking port 25

aaron — Mon, 06 Jul 2009 14:01:32 +0000

Comcast just started blocking port 25 outgoing. I have several computers at home configured to send email reports of cron jobs. Of course they do this by trying to send mail on port 25 from inside the house to my mail server outside. Now that Comcast is blocking that, I need some other way for my emails to be delivered.

The easiest solution I could come up with was to tell my mail server to listen on another port such as 587, and have my firewall route requests for port 25 to port 587. Here is the iptables rule to do that!

iptables -t nat -A PREROUTING -p tcp -i eth0 -d xx.xx.xx.xx --dport 25 -j DNAT --to-destination :587

Where xx.xx.xx.xx is the IP address of my mail server. Now all the computers inside think they are communicating with my mail server on port 25, but the firewall secretly passes the request on to port 587 instead.

Am I really the only one who knows what street I grew up on?

aaron — Wed, 13 May 2009 01:46:01 +0000

The top trending topic on Twitter the other day was #twitterpornname. This seemingly innocent meme prompts you to find your Twitter porn name by combining the name of your first pet with the street you grew up on, or some variation. Thousands of people began shouting out this information on their Twitter profiles.

At this point, little red flags may be going off in your head if you realize that another place you may have seen these questions is… the security questions for your online bank account! “The name of your first pet” and “the street you grew up on” are common security questions asked by many websites, and probably you’ve signed up on a few websites that have asked you these.

This meme quickly caused people to seriously think about online security. On one hand, you have people freely giving out the answers to their security questions for their online banking accounts, their student email accounts, etc.

On the other hand, you have businesses treating this information as if you are the only one who could possibly know it. The whole point of a password is that nobody knows it except you. If I log in to a website and provide my password, the website can be reasonably sure that it is really me logging in. When security questions can be used to reset a password, you’d better be sure that nobody else knows the answers to the security questions.

Why, then, do businesses assume that you are the only one who knows the answers to “what street did you grow up on” or “what is your mother’s maiden name”? Surely you can think of a few other people in your life who know the answers, because they grew up with you, or they are related to you.

So while it’s generally a bad idea to give out the answers to your security questions on Twitter, there is really a bigger issue here.

Note: You may have arrived at this post because you saw my tweet which included my SSN and credit card number. Be assured: this was not my actual SSN or CC#. I was making fun of the fact that people give up personal information so easily.

IMAP Authentication for Wordpress 2.7.1

aaron — Fri, 13 Feb 2009 18:36:59 +0000

Due to some significant changes to the Wordpress authentication mechanism, my original IMAP Authentication plugin stopped working in version 2.7.1. I have updated the plugin to work in 2.7.1. The only difference is that users are no longer automatically created in Wordpress if they have a valid IMAP account. I will try to add that back in soon, but for now this will do.

Download imap-authentication1.2.php


/*
Plugin Name: IMAP Authentication 2
Version: 1.2
Plugin URI: http://blog.neverusethisfont.com/2009/02/imap-authentication-for-wordpress-271/
Description: Authenticate users using IMAP authentication. For Wordpress 2.7.1
Author: Aaron Parecki
Author URI: http://www.aaronparecki.com
 
 
Copyright 2009 by Aaron Parecki  (email : aaron@parecki.com)
 
	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.
 
	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
*/
 
add_action('admin_menu', array('IMAPAuthentication', 'admin_menu'));
add_action('lost_password', array('IMAPAuthentication', 'disable_password'));
add_action('retrieve_password', array('IMAPAuthentication', 'disable_password'));
add_action('password_reset', array('IMAPAuthentication', 'disable_password'));
add_filter('show_password_fields', array('IMAPAuthentication', 'show_password_fields'));
 
add_action('wp_authenticate_user', array('IMAPAuthentication', 'authenticate_user'), 1, 2);
add_filter('check_password', array('IMAPAuthentication', 'check_password'), 1, 4);
 
 
if( is_plugin_page() ) {
    $mailbox = IMAPAuthentication::get_mailbox();
    $user_suffix = IMAPAuthentication::get_user_suffix();
?>
<div class="wrap">
  <h2>IMAP Authentication Optionsh2>
  <form name="imapauthenticationoptions" method="post" action="options.php">
     wp_nonce_field('update-options'); ?>
    <input type="hidden" name="action" value="update" />
    <input type="hidden" name="page_options" value="imap_authentication_mailbox,imap_authentication_user_suffix" />
    <fieldset class="options">
      <table width="100%" cellspacing="2" cellpadding="5" class="form-table">
        <tr valign="top">
        <th width="33%" scope="row"><label for="imap_authentication_mailbox">Mailboxlabel>th>
        <td><input name="imap_authentication_mailbox" type="text" id="imap_authentication_mailbox" value="" size="80" /><br />eg: {mail.example.com/readonly}INBOX or {mail.example.com:993/ssl/novalidate-cert/readonly}INBOXtd>
        tr>
        <tr valign="top">
        <th scope="row"><label for="imap_authentication_user_suffix">User Suffixlabel>th>
        <td><input name="imap_authentication_user_suffix" type="text" id="imap_authentication_user_suffix" value="" size="50" /><br />A suffix to add to usernames (typically used to automatically add the domain part of the login).<br />eg: @example.comtd>
        tr>
      table>
    fieldset>
    <p class="submit">
      <input type="submit" name="Submit" value="" />
    p>
  form>
div>

}
 
if( !class_exists('IMAPAuthentication') ) {
    class IMAPAuthentication {
        /*
         * Add an options pane for this plugin.
         */
        function admin_menu() {
            add_options_page('IMAP Authentication', 'IMAP Authentication', 10, __FILE__);
        }
 
        /*
         * Return the mailbox option from the database, creating the option if it doesn't exist.
         */
        function get_mailbox() {
            global $cache_nonexistantoptions;
 
            $mailbox = get_settings('imap_authentication_mailbox');
            if (! $mailbox or $cache_nonexistantoptions['imap_authentication_mailbox']) {
                $mailbox = '{localhost:143}INBOX';
                IMAPAuthentication::add_mailbox_option($mailbox);
            }
 
            return $mailbox;
        }
 
        /*
         * Add the mailbox option to the database.
         */
        function add_mailbox_option($mailbox) {
            add_option('imap_authentication_mailbox', $mailbox, 'The mailbox to try and log into.');
        }
 
        /*
         * Return the user_suffix option from the database, creating the option if it doesn't exist.
         */
        function get_user_suffix() {
            global $cache_nonexistantoptions;
 
            $user_suffix = get_settings('imap_authentication_user_suffix');
            if (! $user_suffix or $cache_nonexistantoptions['imap_authentication_user_suffix']) {
                $user_suffix = '';
                IMAPAuthentication::add_user_suffix_option($user_suffix);
            }
 
            return $user_suffix;
        }
 
        /*
         * Add the user_suffix option to the database.
         */
        function add_user_suffix_option($user_suffix) {
            add_option('imap_authentication_user_suffix', $user_suffix, 'A suffix to add to usernames (typically used to automatically add the domain part of the login).');
        }
 
        // custom error handler
        function eh($type, $msg, $file, $line, $context)
        {
            $error = $error.$msg;
        }
 
        function authenticate_user(&$user, $password) {
        	global $wpdb;
 
			// Apparently this method is no longer called for users who are not in the WP database
 
			$mbox = imap_open(IMAPAuthentication::get_mailbox(), $user->user_login.IMAPAuthentication::get_user_suffix(), $password, OP_HALFOPEN|OP_READONLY) or $error = imap_last_error();
 
			if ($mbox) {
				$userInfo = get_userdatabylogin($user->user_login);
				imap_close($mbox);
				return new WP_User($userInfo->ID);
			} else {
				do_action( 'wp_login_failed', $user->user_login );
				return new WP_Error('incorrect_password', __('ERROR: Incorrect password. '.$error));
			}
        }
 
		function check_password($unknown, $enteredPassword, $storedPassword, $userID) {
			$user = new WP_User($userID);
			return IMAPAuthentication::authenticate_user($user, $enteredPassword);
		}
 
        /*
         * Used to disable certain login functions, e.g. retrieving a
         * user's password.
         */
        function disable_password() {
            login_header('Login', 'ERROR: You can\'t do that here. This blog uses the IMAP login mechanism. Your password is set with your email account.
', 'error');
			die();
        }
 
        /*
         * Used to disable certain display elements, e.g. password
         * fields on profile screen.
         */
        function show_password_fields($username) {
            return false;
        }
    }
}
?>

IMAP Authentication for Wordpress

aaron — Thu, 28 Aug 2008 08:00:16 +0000

UPDATE 2/13/09: There is a newer version of the IMAP Authentication plugin for Wordpress 2.7.1.

It seems like IMAP authentication would be a pretty basic plugin to find for Wordpress. A google search doesn’t turn up much. I found this one which was apparently written for an older version of Wordpress. Never having written a Wordpress plugin before, naturally I decided to fix it to work with version 2.6.

Below is the result of my efforts. I started with Norman’s code, and modified it until it worked with version 2.6. I apologize if it is written poorly or if I missed something terribly obvious; I’ve never written a Wordpress plugin before.

Download imap-authentication2.php


/*
Plugin Name: IMAP Authentication
Version: 0.1
Plugin URI: http://blog.neverusethisfont.com/2008/08/imap-authentication-for-wordpress/
Description: Authenticate users using IMAP authentication.
Author: Aaron Parecki
Author URI: http://www.aaronparecki.com
 
Assumes a successful login against the IMAP server is a valid user, and auto-creates
the user in Wordpress if they don't already exist.
 
 
 
Copyright 2007 by Aaron Parecki  (email : aaron@parecki.com)
 
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
 
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
 
*/
 
add_action('admin_menu', array('IMAPAuthentication', 'admin_menu'));
add_action('lost_password', array('IMAPAuthentication', 'disable_password'));
add_action('retrieve_password', array('IMAPAuthentication', 'disable_password'));
add_action('password_reset', array('IMAPAuthentication', 'disable_password'));
add_filter('show_password_fields', array('IMAPAuthentication', 'show_password_fields'));
 
 
if( is_plugin_page() ) {
    $mailbox = IMAPAuthentication::get_mailbox();
    $user_suffix = IMAPAuthentication::get_user_suffix();
?>
<div class="wrap">
  <h2>IMAP Authentication Optionsh2>
  <form name="imapauthenticationoptions" method="post" action="options.php">
     wp_nonce_field('update-options'); ?>
    <input type="hidden" name="action" value="update" />
    <input type="hidden" name="page_options" value="imap_authentication_mailbox,imap_authentication_user_suffix" />
    <fieldset class="options">
      <table width="100%" cellspacing="2" cellpadding="5" class="form-table">
        <tr valign="top">
        <th width="33%" scope="row"><label for="imap_authentication_mailbox">Mailboxlabel>th>
        <td><input name="imap_authentication_mailbox" type="text" id="imap_authentication_mailbox" value="" size="80" /><br />eg: {mail.example.com/readonly}INBOX or {mail.example.com:993/ssl/novalidate-cert/readonly}INBOXtd>
        tr>
        <tr valign="top">
        <th scope="row"><label for="imap_authentication_user_suffix">User Suffixlabel>th>
        <td><input name="imap_authentication_user_suffix" type="text" id="imap_authentication_user_suffix" value="" size="50" /><br />A suffix to add to usernames (typically used to automatically add the domain part of the login).<br />eg: @example.comtd>
        tr>
      table>
    fieldset>
    <p class="submit">
      <input type="submit" name="Submit" value="" />
    p>
  form>
div>

}
 
if( !class_exists('IMAPAuthentication') ) {
    class IMAPAuthentication {
        /*
         * Add an options pane for this plugin.
         */
        function admin_menu() {
            add_options_page('IMAP Authentication', 'IMAP Authentication', 10, __FILE__);
        }
 
        /*
         * Return the mailbox option from the database, creating the option if it doesn't exist.
         */
        function get_mailbox() {
            global $cache_nonexistantoptions;
 
            $mailbox = get_settings('imap_authentication_mailbox');
            if (! $mailbox or $cache_nonexistantoptions['imap_authentication_mailbox']) {
                $mailbox = '{localhost:143}INBOX';
                IMAPAuthentication::add_mailbox_option($mailbox);
            }
 
            return $mailbox;
        }
 
        /*
         * Add the mailbox option to the database.
         */
        function add_mailbox_option($mailbox) {
            add_option('imap_authentication_mailbox', $mailbox, 'The mailbox to try and log into.');
        }
 
        /*
         * Return the user_suffix option from the database, creating the option if it doesn't exist.
         */
        function get_user_suffix() {
            global $cache_nonexistantoptions;
 
            $user_suffix = get_settings('imap_authentication_user_suffix');
            if (! $user_suffix or $cache_nonexistantoptions['imap_authentication_user_suffix']) {
                $user_suffix = '';
                IMAPAuthentication::add_user_suffix_option($user_suffix);
            }
 
            return $user_suffix;
        }
 
        /*
         * Add the user_suffix option to the database.
         */
        function add_user_suffix_option($user_suffix) {
            add_option('imap_authentication_user_suffix', $user_suffix, 'A suffix to add to usernames (typically used to automatically add the domain part of the login).');
        }
 
        // custom error handler
        function eh($type, $msg, $file, $line, $context)
        {
            $error = $error.$msg;
        }
 
        function login($username, $password) {
        	global $wpdb;
 
			$mbox = imap_open(IMAPAuthentication::get_mailbox(), $username.IMAPAuthentication::get_user_suffix(), $password, OP_HALFOPEN) or $error = imap_last_error();
 
			if ($mbox) {
				$user = get_userdatabylogin($username);
 
				if( $user === false ) {
					// the user checked out on the IMAP server, but there was no record in the database. Automatically add it now.
					$wpdb->query( $wpdb->prepare("INSERT INTO $wpdb->users (user_login, user_nicename, user_email, display_name) VALUES(%s, %s, %s, %s)", $username, $username, $username.IMAPAuthentication::get_user_suffix(), $username) );
					$user = get_userdatabylogin($username);
 
					$wpdb->query( $wpdb->prepare("INSERT INTO $wpdb->usermeta (user_id, meta_key, meta_value) VALUES(%d, %s, %s)", $user->ID, 'nickname', $username) );
					$wpdb->query( $wpdb->prepare("INSERT INTO $wpdb->usermeta (user_id, meta_key, meta_value) VALUES(%d, %s, %s)", $user->ID, 'rich_editing', 'true') );
					$wpdb->query( $wpdb->prepare("INSERT INTO $wpdb->usermeta (user_id, meta_key, meta_value) VALUES(%d, %s, %s)", $user->ID, 'wp_capabilities', 'a:1:{s:6:"author";b:1;}') );
					$wpdb->query( $wpdb->prepare("INSERT INTO $wpdb->usermeta (user_id, meta_key, meta_value) VALUES(%d, %s, %s)", $user->ID, 'wp_user_level', '2') );
 
				}
 
				imap_close($mbox);
				return new WP_User($user->ID);
			} else {
				do_action( 'wp_login_failed', $username );
				return new WP_Error('incorrect_password', __('ERROR: Incorrect password.'));
			}
        }
 
        /*
         * Used to disable certain login functions, e.g. retrieving a
         * user's password.
         */
        function disable_password() {
            login_header('Login', 'ERROR: You can\'t do that here. This blog uses the IMAP login mechanism. Your password is set with your email account.
', 'error');
			die();
        }
 
        /*
         * Used to disable certain display elements, e.g. password
         * fields on profile screen.
         */
        function show_password_fields($username) {
            return false;
        }
    }
}
 
 
if( !is_plugin_page() ) :
 
function wp_authenticate($username, $password) {
	return IMAPAuthentication::login($username, $password);
}
endif;
 
 
?>

Google Treasure Hunt – Question 2

aaron — Tue, 20 May 2008 03:35:12 +0000

I just stumbled across Google’s Treasure Hunt. They’re always doing neat things, so I checked it out. It’s a series of four problem-solving puzzles released one week at a time. I found out about it after the first question was already over, so I jumped in starting with the second question.

Question 2: File sum and multiplication problem

In this problem you are given a zip folder with hundreds of text files nested in folders an arbitrary number of levels deep. The question asks to find the sum of the nth line of all files with abc in their path, ending in .xyz. You do this twice, then calculate the product of the two sums. You can download the file I got from them at the link below.
googletreasurehunt.zip

My question is below:

Sum of line 3 for all files with path or name containing jkl and ending in .rtf
Sum of line 5 for all files with path or name containing stu and ending in .rtf
Multiply all the above sums together and enter the product below.

I thought this would be a good chance to practice my bash scripting, so I decided to give it a shot.

$ find . -type f -wholename "*jkl*\.rtf"

-type f restricts the search to files, not directories. -wholename searches for files matching that pattern. Once we run this, we get a list of all the files we’ll need to process. Now we need to create a running total of the values in the nth line in each file. This is where a bash ‘for’ loop and ‘awk’ come in handy.

$ for x in $(find . -type f -wholename "*jkl*\.rtf")

The ‘$’ tells bash to execute that command and return the result. The ‘for’ loop looks at the output line by line, and the variable x will contain each filename.

$ awk 'NR==3' filename.txt

This is an awk command that prints the 3rd line of filename.txt. If we can stick this into the ‘for’ loop, we can get a running total.

sum1=0
for x in $(find . -type f -wholename "*jkl*\.rtf")
do
        sum1=$(( `awk 'NR==3' $x` + $sum1 ))
done
echo $sum1

Now we just repeat for the other pattern, and we end up with our sum in two variables. Calculating the product is simple.

echo $(( $sum1 * $sum2 ))

Personally, I thought this puzzle was a little bit simplistic. I would have expected them to throw in some tricks, so that a poorly written search command would return some other files that would mess with your result. Now that I’ve said that, I hope I got it right! I find out in 10 hours if my answer is correct.

Feel free to comment if you have a different and/or better solution to this problem!

Phone as a Wifi access point!

aaron — Sat, 19 Apr 2008 21:34:57 +0000

This is pretty much the coolest thing in the world! I am posting from my laptop which is connected to my cell phone’s wifi connection, using Sprint’s EVDO connection to the internet. The software that enables me to do this is called wmwifirouter. Earlier this month they released their first final version of the software, and started charging for it. It’s not outrageously priced, but you can still find the earlier free versions on the internet if you search for versions 0.90 or 0.89.

Sprint’s EVDO connection is actually pretty speedy. Of course it’s not like having a cable connection, but it’s definitely faster than dialup. I downloaded a 2mb file at a solid 85kb/s. Also see below for a traceroute to this server.

C:\Documents and Settings\Aaron Parecki>tracert blog.neverusethisfont.com
 
Tracing route to blog.neverusethisfont.com [67.18.176.91]
over a maximum of 30 hops:
 
  1     6 ms     2 ms     3 ms  192.168.0.1
  2   141 ms   124 ms   124 ms  68.28.57.69
  3     *        *        *     Request timed out.
  4   131 ms   132 ms   134 ms  68.28.59.55
  5     *        *        *     Request timed out.
  6   121 ms   120 ms   121 ms  68.28.63.5
  7     *        *        *     Request timed out.
  8   135 ms   129 ms   128 ms  68.28.59.18
  9   136 ms   123 ms   128 ms  sl-gw20-phx-0-0-0.sprintlink.net [144.224.27.5]
 10   143 ms   130 ms   243 ms  sl-bb21-phx-11-0-0.sprintlink.net [144.232.23.199]
 11   141 ms   142 ms   138 ms  sl-bb25-ana-6-0-0.sprintlink.net [144.232.8.74]
 12   169 ms   131 ms   138 ms  ggr3-p330.la2ca.ip.att.net [192.205.33.189]
 13   156 ms   154 ms   156 ms  12.127.3.210
 14   154 ms   151 ms   151 ms  tbr1.dlstx.ip.att.net [12.122.10.49]
 15   153 ms   151 ms   154 ms  12.122.100.49
 16   150 ms   151 ms   152 ms  12.87.41.150
 17   324 ms   207 ms   203 ms  te7-2.dsr01.dllstx3.theplanet.com [70.87.253.10]
 18   160 ms   155 ms   151 ms  7e.fd.5746.static.theplanet.com [70.87.253.126]
 19   163 ms   154 ms   154 ms  vl1.car02.dllstx2.theplanet.com [12.96.160.12]
 20   154 ms   153 ms   150 ms  theia.parecki.com [67.18.176.91]
 
Trace complete.
C:\Documents and Settings\Aaron Parecki>