Free, unlimited Dropbox alternative: BitTorrent Sync

BitTorrent SyncUnless you’ve been living in a cave for the last five years, you’ll have heard of cloud sync poster child Dropbox. Dropbox has many flaws, but its great strength is how simple it is to use (my most inept users can manage it).

When you read elsewhere about the weaknesses of Dropbox, privacy seems to be the big one. Your files are stored “in the cloud”. This doesn’t particularly trouble me. Yes, Dropbox has my stuff, but the chances are that Dropbox’s security measures are better than my own. Between my laptop being hacked/stolen and Dropbox being hacked(/stolen?!), my money’s on my laptop. (I use TrueCrypt to encrypt my laptop’s hard drive, as you should by the way, but that’s a different story.) Anyway, any squeamishness we have about cloud storage is likely to die away in the near future, when it’s no longer quite so new and scary.

Of course there are lots of companies on the cloud storage bandwagon, big names and small. There are Google Drive, Microsoft SkyDrive, CrashPlan, Mozy and so on. Typical features include:

  • Mobile apps
  • Entry-level free option
  • File version revision/undelete

This is different. From the company that brings you the controversial peer-to-peer file sharing system and the popular BitTorrent client, µTorrent, comes a new “cloud-less” file sync technology, BitTorrent Sync. The principle of BitTorrent sync is that you use the efficient BitTorrent protocol to distribute your own files privately amongst approved devices.

This year, BT Sync has been in private “alpha” (software in heavy testing, likely to contain bugs, which may be serious). Last week, the public alpha was released. It’s currently available for Windows, Mac and Linux.

The Windows interface is pretty minimal at the moment:

BT Sync Windows

The web interface for the Linux version is more polished:

BitTorrent Sync Linux

During the private alpha stage, I tried syncing between a Windows 7 laptop and a Linux server. Shortly after this, the server suffered a catastrophic disk failure. Coincidence? Not entirely, I suspect. There may be some low-level disk calls that overtaxed drives that were already heading towards the end of their life. Nevertheless, it’s a reminder: this is alpha (experimental) software; be careful.

BT Sync has quite a few limitations:

  • It’s still in alpha state, which means it is liable to eat your data, your hard drive and your children’s pet rabbit.
  • There are no mobile applications yet.
  • No progress indicators within Windows, just an irritating balloon tip.
  • Since there is no central cloud, the devices must be online simultaneously, to perform sync.
  • For the same reason, you can’t download files via the web.
  • Other than creating a folder specifically for the purpose, there’s no option to “share” a single file.
  • No versioning – no backup or undelete facility outside any provided by your operating system.

Despite all this, there are some pretty compelling reasons for using it:

  • There are absolutely no limits. Unlimited file size, unlimited storage, unlimited bandwidth, etc. Of course you will still be limited by other factors – the size of your hard drive and the amount of monthly bandwidth you’re allocated by your ISP.
  • Efficiency. This is not the place to discuss BitTorrent generally, but the more people sharing the files, the better. All connected devices, while online, can participate in the synchronisation process.
  • Privacy. No third party holds your data. Central systems facilitate the peer-to-peer connection, but do not take their own copies of files.
  • Security. The data is encrypted before transmission and only accessible using a “shared secret”.

BitTorrent Sync has an ace up its sleeve. It can be installed on several different NAS boxes, from the likes of Synology, QNAP, Iomega, etc. This is where I can see BT Sync excelling. Want an entirely private, shared data store for remote office workers, but don’t want to invest in high-end storage systems? Give them all a NAS box with BT Sync installed. Want to set up off-site backup for your files at home? Enter into a reciprocal arrangement with a friend, using NAS boxes, where you host each other’s backup files. Want to set up a sprawling hydra-like network of anarchic file storage for your clandestine underground organisation? You get the idea…

Download

So, having read all my caveats above, you still want to give this a whirl? Go ahead, don your crash helmet and download the sucker.

Easy Password-less SSH logins on Linux

ssh-copy-idI’m storing this as an aide memoire, really, but it may help you too.

Let’s say we have two systems, System_From and System_To. And two users, User_From and User_To. The objective is: log on to System_To as User_To, from System_From as User_From.

The steps

1. One-time key generation for User_From

On System_From, while logged on as User_From, proceed as follows:

[email protected]_From:~$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/User_From/.ssh/id_rsa):[hit enter]
Enter passphrase (empty for no passphrase):[hit enter]
Enter same passphrase again:[hit enter]
Your identification has been saved in /home/User_From/.ssh/id_rsa.
Your public key has been saved in /home/User_From/.ssh/id_rsa.pub.
The key fingerprint is:
be:e8:98:4a:26:1e:9b:ed:78:a7:e7:fe:d8:9d:3c:6d [email protected]_From
The key's randomart image is:
+--[ RSA 2048]----+
|                 |
|  E              |
|                 |
|               Q |
|        S        |
|       .         |
|oo      o     o  |
|+.Bo8ooo.E       |
| BOB++o++        |
+-----------------+

Note: if you use anything other than an empty passphrase, you will need to enter the passphrase each time you log on, which sort of defeats the object of this exercise!

This creates two files: id_rsa and id_rsa.pub. The private key, id_rsa, must always be kept secret. Your system should have marked it read/write for the owner only. The public key, id_rsa.pub is safe to copy to destination systems (see next section).

2. Copy the public key to System_To

OpenSSH comes with a handy script for copying the public key to the remote host (System_To, in this instance): ssh-copy-id. Use it like this, at the system you’re connecting from:

[email protected]_from:~$ ssh-copy-id -i ~/.ssh/id_rsa.pub [email protected]_To
[email protected]_To's password:[type User_To's password and hit enter]
Now try logging into the machine, with "ssh '[email protected]_To'", and check in:

  ~/.ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

If you’re connecting to SSH on a custom port, the command is thus:

ssh-copy-id -i ~/.ssh/id_rsa.pub "[email protected]_To -p custom#"

Repeat this step for all remote hosts to which you intend to connect.

3. Log in to System_To

Now, when you issue the command ssh System_To, you will be logged in straight away, with no password prompt.

SOLVED: “Access is denied, unable to remove” when deleting printer

Many organisations push out printer installations via Active Directory. If you want to tidy up those printers (removing ones you don’t use) you may find Windows 7 doesn’t let you delete them, even though you may be a local administrator and even if you use an elevated Explorer session:

Access denied error

Use the following steps to resolve this annoyance.

From an elevated command prompt:

C:\Windows\system32>net stop spooler
The Print Spooler service is stopping.
The Print Spooler service was stopped successfully.

Then fire up regedit. Navigate to Computer\HKEY_CURRENT_USER\Printers\Connections and delete the offending printer:

printers regedit

Finally, restart the print spooler:

C:\Windows\system32>net start spooler
The Print Spooler service is starting.
The Print Spooler service was started successfully.

From CodeIgniter to Laravel | part 4: managing databases

UPDATE: I have re-written this article for the new Laravel 4. You’ll find the updated article over at Geek & Dummy.

Contents


AVZ DatabaseFor almost all my previous web design, I’ve used phpMyAdmin to administer the databases. I speak SQL, so that has never been a big deal. But Laravel comes with some excellent tools for administering your databases more intelligently and (most importantly!) with less effort. Migrations offer version control for your application’s database. For each version change, you create a “migration” which provides details on the changes to make and how to roll back those changes. Once you’ve got the hang of it, I reckon you’ll barely touch phpMyAdmin again.

Configuration

So let’s assume that I’m creating a new website about ducks. When I created the virtual host, Virtualmin also created my “ducks” database. I’m going to create a MySQL user with the same name, with full permission to access the new database. Here’s how I do that from a root SSH login:

echo "GRANT ALL ON ducks.* TO 'ducks'@localhost IDENTIFIED BY 'newpassword';" | mysql -p
Enter password:[root MySQL password]

This creates a new MySQL user, “ducks” and gives it all privileges associated to the database in question. Next we need to tell Laravel about these credentials. The important lines in the file application/config/database.php are:

<?php
return array(

//...

	'default' => 'mysql',

	'connections' => array(

//...

		'mysql' => array(
			'driver'   => 'mysql',
			'host'     => '127.0.0.1',
			'database' => 'ducks',
			'username' => 'ducks',
			'password' => 'newpassword',
			'charset'  => 'utf8',
			'prefix'   => '',
		),

//...

	),

//...

);

Initialise Migrations

The migration environment must be initialised for this application. We do this using Laravel’s command line interface, Artisan. From an SSH login:

php artisan migrate:install
Migration table created successfully.

This creates a new table, laravel_migrations, which will be used to track changes to your database schema (i.e. structure), going forwards.

My ducks application will have a single table to start with, called “ducks” [Note: it is significant that we’re using a plural word here; I recommend you follow suit]. This table does not yet exist; we will create it using a migration. To kick this off, use the following Artisan command:

php artisan migrate:make create_ducks_table
Great! New migration created!

This will create a new file named something like “2013_04_15_085356_create_ducks_table.php”. If, like me, you’re developing remotely, you’ll need to pull this new file into your development environment. In NetBeans, for example, right-click the migrations folder, click “download” and follow the wizard.

You can deduce from the naming of the file that migrations are effectively time-stamped. This is where the life of your applications database begins. The migrations file will look a bit like this:

<?php

class Create_Ducks_Table {

	/**
	 * Make changes to the database.
	 *
	 * @return void
	 */
	public function up()
	{
		//
	}

	/**
	 * Revert the changes to the database.
	 *
	 * @return void
	 */
	public function down()
	{
		//
	}

}&#91;/php&#93;

As you can probably guess, in the "up" function, you enter the code necessary to create the new table (to move "up" a migration) and in the "down" function, you do the reverse (to move "down" or to roll back a migration).

<h1>Create first table</h1>

Your first migration will probably be to create a table (unless you have already created or imported tables via some other method).  Naturally, Laravel has a class for this purpose, the <a href="http://laravel.com/docs/database/schema" target="_blank">Schema class</a>.  Here's how you can use it, in your newly-created migrations php file:

<?php

class Create_Ducks_Table {

	/**
	 * Make changes to the database.
	 *
	 * @return void
	 */
	public function up()
	{
		Schema::create('ducks', function($table) {
				$table->increments('id');              // auto-incrementing primary key
				$table->string('name', 255);           // varchar field; length 255 characters
				$table->date('birthdate')->nullable(); // can be empty
				$table->boolean('can_fly')->default(TRUE);
				$table->integer('children')->unsigned();
				$table->text('biography');
				$table->timestamps(); // special created_at and updated_at timestamp fields
		});	
	}

	/**
	 * Revert the changes to the database.
	 *
	 * @return void
	 */
	public function down()
	{
		Schema::drop('ducks');
	}

}

To run the migration (i.e. to create the table), do the following at your SSH login:

php artisan migrate
Migrated: application/2013_04_15_085356_create_ducks_table

That creates the table, as described. And if you need to roll back:

php artisan migrate:rollback
Rolled back: application/2013_04_15_085356_create_ducks_table

This removes the table.

By examining the Schema class documentation, you’ll see how you can use future migrations to add or remove fields, create indexes, etc. In my next tutorial, I’ll have a look at using databases in your application.

AVZ Database image copyright © adesigna, licensed under Creative Commons. Used with permission.

From CodeIgniter to Laravel | part 3: installing external libraries

UPDATE: I have re-written this article for the new Laravel 4. You’ll find the updated article over at Geek & Dummy.

Contents


LibraryAs a fan of CodeIgniter, I was very pleased when the Sparks project came on the scene, offering a relatively easy way to integrate third-party libraries/classes into your project. Laravel has a similar and arguably more feature-rich analog in Bundles. With a bit of luck, the third-party library you require has already been converted to a Laravel bundle, making installation a snip.

Let’s say, for example, we’re going to build a web-scraping application. The first two libraries I’d consider adding to the project would be the Requests HTTP library and the PHP Simple HTML DOM Parser.

From an SSH login, at the root of your project, issue the following command:

php artisan bundle:install requests phpsimplehtmldom

You should be greeted with the following results:

Fetching [requests]...done! Bundle installed.
Fetching [phpsimplehtmldom]...done! Bundle installed.

The file application/bundles.php will probably contain code along the following lines:

<?php

/*
 &#91;...various comments...&#93;
*/

return array(

	'docs' => array('handles' => 'docs'),

);

Register the new libraries like this:

return array(

	'docs' => array('handles' => 'docs'),
	'requests' => array('auto' => TRUE),
	'phpsimplehtmldom' => array('auto' => TRUE),

);

And use like this:

		$HDM = IoC::resolve('HtmlDomParser'); // Give us a hook into the library; Requests doesn't need this

		// Request the HTML page
		//$headers = array('Accept' => 'application/html');
		$headers = array();
		//$options = array('auth' => array('user', 'pass'));
		$options = array();
		$request = Requests::get('http://some.domain/some/page', $headers, $options);
		if($request->status_code != 200) {
			// Handle error retrieving page
		}

		$dom = $HDM::str_get_html($request->body);

		// Options
		$options = $dom->find('#somediv option');
		foreach($options as $option) {
			echo $option->value.' | '.$option->innertext."<br />";
		}

There’s a lot more to this IoC thing than meets the eye. To be frank, it’s above my head. I’m also not convinced I fully understand registering bundles. But, like CodeIgniter, learning is a process of immersion in the framework. I’m pretty sure than in a couple of years I’ll laugh at the code above. So all I ask is please be gentle in the comments. 😉

Library image copyright © Janne Moren, licensed under Creative Commons. Used with permission.

From CodeIgniter to Laravel | part 2: orientation

UPDATE: I have re-written this article for the new Laravel 4. You’ll find the updated article over at Geek & Dummy.

Contents


Signpost at North Point, Barbados, Feb.1998I’ve used CodeIgniter for many years, but I have always, I confess, proceeded knowing just enough to get by. So forgive me if my approach seems a little clunky. I have never, for example, used CodeIgniter’s routes. I like my web application files nicely categorised into Model, View, Controller, Library and, if absolutely necessary, Helper.

Controllers

So for now, I want to carry on using Controllers, if that’s okay with you. Controllers are stored under application/controllers. Sound familiar?

Here’s a sample controller:

<?php

// application/controllers/news.php
class News_Controller extends Base_Controller {

	public function action_index() {
		echo "News index page.";
	}

	public function action_item($item) {
		echo "News item $item.";
	}

}
?>

In CodeIgniter, that’s all you would have needed to do, due to automatic routing. In Laravel, you need also to add the following to application/routes.php:

Route::controller('news');

To view these pages, you just visit yourdomain/news (/index is implied) and yourdomain/news/item/x (where x will probably refer to a specific news item, possibly by data id).

Note the naming of the functions – action_item, etc. The part after the underscore represents a “method” or page of your web site. Laravel’s routing magic makes sure you get the correct function. If you’re creating a RESTful API, you can use additional function names beginning get_, post_, etc. Check the Laravel documentation for more.

Views

Views are pretty straightforward and similar to CodeIgniter. Place them in application/views. Extending the example above, our controller could now look like this:

<?php

// application/controllers/new.php
class News_Controller extends Base_Controller {

	public function action_index() {
		echo "News index page.";
	}

	public function action_item($id) {
		$data = array('id' => $id);
		return View::make('results', $data);
	}

}

?>

Note that data can also be passed through to a view like this:

	public function action_item($id) {
		return View::make('item', $data)
		    ->with('id' => $id);
	}

And then your view (application/views/item.php) could be like this:

<h1>News flash</h1>
<p>This is news item <?php echo $id; ?>.</p>

Obviously your real views will be more syntactically complete.

Models

Models are created under application/models. Unlike CodeIgniter, Laravel comes with its own object relational mapper. In case you’ve not encountered the concept before, an ORM gives you a convenient way of dealing with database tables as objects, rather than merely thinking in terms of SQL queries. CodeIgniter has plenty of ORMs, by the way, it just doesn’t ship with one as standard.

Laravel’s built-in ORM is called “Eloquent”. If you choose to use it (there are others available), when creating a model, you extend the Eloquent class. Eloquent makes some assumptions:

  • Each table contains a primary key called id.
  • Each Eloquent model is named in the singular, while the corresponding table is named in the plural. E.g. table name “newsItems”; Eloquent model name “newsItem”.

You can override this behaviour if you like, it just makes things a bit more convenient in many cases.

Example model application/models/newsItem.php:

<?php
class NewsItem extends Eloquent {

}

(You can omit the closing ?> tag.)

Because the Eloquent class already contains a lot of methods, you do not necessarily need to do more than this. In your controllers, you could for example now do this:

$items = NewsItem::all();

foreach ($items as $item) {
  // Do stuff here
}

This is barely scratching the surface. Head on over to the official Laravel documentation for much more on all this.

Signposts image copyright © Andrea_44, licensed under Creative Commons. Used with permission.

SOLVED: “Failed to initialize connection subsystem” in Cisco AnyConnect

AnyConnect logoTalk about obscure.

One of my end users was greeted by this informative error message recently. He was connecting to the internet using a 3G dongle and then to our network via Cisco AnyConnect VPN. “Software reinstall!” thought I. “Wrong!” said Google.

Although this is probably due to faulty programming on Cisco’s part, the culprit is Internet Explorer. (How I love to blame that historically stinky pile of poodoo.)

To resolve: load up IE. If you can’t see the [ File | Edit | View… ] menus, press Alt, to bring it up. On the File menu, “Work Offline” is almost certainly checked. Uncheck it. Connect again. Job done. Who knew.

If you’re using Internet Explorer 11, bad news: Microsoft removed the “Work offline” option from the File menu. Gone. So there’s no GUI interface to the relevant setting. In fact it’s a registry key called “GlobalUserOffline”, found at HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings. You need to set it to 0, disable “Work offline”. This registry file should do the trick: DisableWorkOffline.reg.