Padd Solutions

Farewell http://me.clustur.com.

This week I decided to move over my blog to Blogger for a few reasons, but the main ones boiled down to spam and the inconvenience of hosting my own blog.

The spam problem was outrageous, I would leave my blog for a week only to find literally hundreds of spam comments. I'd write a script to weed out the new spam comments and I'd improve the anti-spam measures and CAPTCHA's. The next week the same exact thing would happen. Note to self and others: CAPTCHA's do nothing against determined spammers. I could require people to create accounts with my blog in order to comment, but who would go to the trouble to sign up just to comment?

I also got a little tired of keeping up a server for this blog. Our internet and power go out way to much for me to trust anything on my sites. My poor little server could never keep up when a site experienced the Digg or Reddit effect, either. I also found out the hard way that server motherboards will not survive nearby strikes of lightning. That was fun.


Well, it's been real. Let's take a moment to pour over all the great memories we used to have together:


OK enough of that. We live in the present. Over the next week or so, I'll be phasing out the site and eventually shutting it down, with the exception of a few data folders that might need to stay up. This is the first post not on the old blog. Here's to change for the better.

I've been working on a new site on and off for the past month and the fruit of my labor has finally surfaced: hotsteeze.com.

Hotsteeze is an action sports site for logging (and sharing, if you want) tricks that you have learned. Skateboarding and other action sports, ever since they began, have been very disorganized. The best collection of tricks up to now has been all the videos scattered throughout YouTube. I've been working on cataloging as many tricks as possible. Hopefully, the database of tricks will provide a more conductive environment for discovering new tricks to learn.

Hotsteeze still has a long way to go to get to where I picture it being, but I hope to continue work on it for a long time.

Over the past couple of months, I've been using what little free time I have to code a website called Clustur. It is located at http://clustur.com. The main page pretty much says it all, but it's basically a site for creating, learning, and sharing study material. I've recently used it to study for all of my exams this semester. Because it passed the test of exams for me, I can say it's helped me a ton during the process.


It's coded in Django, which helped a lot because I was able to use much of the built-in functionality. Right now it's still hosted on my home server, which is slow as molasses. Once Clustur starts getting used by people, I'll move it over to a WebFaction server. I'll also admit that it needs a bit of user interface tweaking, but for the most part everything is solid. I also have some great plans with which to extend this site, but I'll let it be a surprise when they are ready to release.

I decided to upload many of my favorite programming projects I worked on years ago back in my Windows days. Yes, almost 1GB of code. The size of my old code directory totals almost 4GB, but I'm only including the most developed projects here. I'm releasing this code in the hopes that someone will find it useful. But please keep in mind that this is unsupported, undocumented, and (largely) uncommented code. Keep in mind that this code was written when I was about 12 or 13 so please don't use this as a measure of my current programming skills. I am releasing all of this code under the GNU Public License. Use it as you wish. Enjoy!

Here is the link!

Many people are aware that they can SSH into their iPod or iPhone from their computers. The fact that the iPhone can be an SSH client is often overlooked, though. It can even authenticate with RSA keys. In this guide I will demonstrate how to set up an iPhone or iPod to SSH into a computer with an RSA key.

This guide assumes that your device is jailbroken, and the OpenSSH package is installed. OK, so let's get down to business. The first step is to SSH into your device using:
After that, you will be in mobile's home directory. You can then generate the local RSA key using:
You will need to just press enter at all prompts. You should now have a file called id_rsa.pub in the hidden .ssh directory. The next step is to copy the id_rsa.pub file onto the computer you want to be able to SSH into. The method does not matter here, and it may or may not be a two step process. The home folder of the user you want is the easiest place to put id_rsa.pub. Here is an easy way to copy it from your device to the destination via SCP:
At this point you can exit out of your device SSH session. Once id_rsa.pub is in the home directory that you want on the server, somehow log in as that user and run:
This will copy the public key into the list of keys that the SSH server will accept. After this step you can delete the id_rsa.pub file from your home folder. And that is the last step! If everything worked correctly you should be able to open up Terminal on your jailbroken iPod/iPhone and SSH into the computer you set this up on!
If you have any questions/comments, feel free to post in the comment sections. I'll do my best to answer.

When I was setting up my server, I was faced with the problem of configuring subdomains to work with a dynamic DNS service such as DynDNS or No-IP. I recently had a user on the Ubuntu Forums ask me how I ended up getting things to work, so I wrote this article to explain.

The first step is to configure settings with your dynamic DNS service. The following instructions are for No-IP, but they should be very similar to other services such as DynDNS:

1. Navigate to the settings page for your domain.
    
2. Find the "Enable wildcards" option and enable it. This directs all domain requests, no matter the subdomain, to Apache. Here is a picture for No-IP:

After configuring your provider, next we need to configure Apache. In order to direct to the right location on the server, you need to configure Apache to know where each subdomain should be directed.

1. On your server, navigate to /etc/apache2/sites-available. This path is for Ubuntu, you will probably need to work with httpd.conf on other systems. This is where Apache gets information about sites and subdomains on Ubuntu.
    
2. If you have not already done so already, create a new .conf file. Although you can name it whatevery you want, it is useful to name it with the format, [yourdomain.com].conf. This file will be used instead of default because it is easer (for me at least) to start from scratch for something like this.
    
3. Open up the file, and add the following lines:

   <VirtualHost *>
   DocumentRoot /var/web/www
   </VirtualHost>

   This is the main entry, it directs all of the undefined subdomains (which we will define later - be patient) to /var/web/www. Of course, you will need to add your own configuration like log files; this is just the bare minimum to get you going. The path can be whatever you like. Note that your changes will not be added until step #6, so hang out.
    
4. Now you can define other subdomains and their paths. Here is an example for foo.clustur.com:

   <VirtualHost *>
   ServerName foo.clustur.com
   DocumentRoot /var/web/foo
   </VirtualHost>

   Notice the only difference is the ServerName attribute. You can add as many of these directives as you would like into your .conf file.
    
5. Now we need to enable the settings we just made:

   sudo a2dissite default
   sudo a2ensite [yourdomain.com].conf

   The first line disables the old default configuration file, and the second line enables your new .conf file, whatever you named it.
    
6. Finally, we can restart apache:

   sudo /etc/init.d/apache2 graceful

   Now all of your subdomains should work! If you're stumped or have any suggestions, please feel free to comment - I'll do my best to help you out.

My server used to have a 16GB hard drive, and did not receive regular automated backups. I wanted to upgrade the drive to an 80GB one and use the old drive for automatic backups. This switch required that I somehow move the entire server installation from the old to the new, larger drive. So I decided to use a tool called Clonezilla. I cloned the old drive onto the new drive, and set the new drive to the master. Booting up with the new drive worked fine. I put in the old drive (which still had the server installation) as a slave for backups. It was then that I ran into an interesting problem: no matter what I did, the old drive would always boot instead of the new one. After some probing, I found out that GRUB was run on the new drive, but it always pointed to the old drive. After about 6 hours of banging my head against the wall, I finally figured out that the UUIDs for the two drives were the same since they were cloned. Instead of using the generic (hd0,0), the Ubuntu distribution uses UUIDs by default to point to the drive that should be booted from. The UUIDs were not so universally unique anymore, and GRUB got confused and booted the old drive. So I guess the moral of the story is always make sure you change the UUIDs whenever a cloned drive is used. Anyways, sorry if this notice came too late. I hadn't expected to run into such trouble.

For reference, here's the steps to change a duplicate UUID:

1. Run uuidgen to generate a new UUID.
    
2. Type in tune2fs /dev/hdaX -U [newuuid] to actually update the partition's UUID. Be sure to replace hdaX with the correct partition and [newuuid] with the UUID given by uuidgen.
    
3. Verify that the UUID was changed properly with vol_id /dev/hdaX.

All bundled up, the command is uuidgen | xargs tune2fs /dev/hdaX -U ; vol_id /dev/hdaX. If you just need to clear out the old drive with the duplicate ID, reformatting it would do the trick, too.

If some of you are wondering, this is the source of the recent downtime my server went through. The sites that were affected included this one, and my NXT++ and Linux4nano wikis. The sites were on and off for about a period of 24 hours. I hope this short tutorial helps some people solve the problems I experienced.

So you know how to install Microsoft Office, upgrade drivers, and maybe even do a little overclocking or programming here and there. But have you ever wanted to know more about a computer - how it really works? Here are just a few ways that you can learn a bit more about the mysterious machine.

1. Open up your computer This is a fun, interactive way to learn what's really under the hood. You can learn a lot by opening something up and picking out what the different parts do. Here is a link that explains some of the details. Although opening a computer might be a little intimidating for some people, keep in mind that computer parts are very durable, even if you have a laptop. It's also safe, as long as you unplug it from the wall first! :-)
    
2. Set up a home server with an old computer Pretty much everyone has at least one old piece of crap computer laying around. One of the best uses for a computer like that is to set it up as a home web server. It can teach you a lot about the Internet and also let you host your own site!
    
3. Install Linux This can teach you tons about how a computer boots and what an operating system really does. Installing a Linux distro like Ubuntu is good since everything is open source. Linux also exposes many advanced and low level functionality that Windows and OSX try to build a wall around. By using Linux, you can tinker and examine with parts that are hidden in other operating systems.
    
4. Upgrade your PC components Has your computer gotten too slow to run the latest games or applications, or do you just want a general speed up? Instead of buying a brand new $500 computer, try upgrading individual components like the RAM, graphics card, or CPU. This can be much cheaper, and is not as difficult as you may think.
    
5. Learn a low-level programming language Everything that runs on a computer was written with a programming language. Low-level languages like C and Assembly teach you the most because they are more connected to the computer's memory. C is a great language to learn, but if you really want to understand computers, learn Assembly.
    
6. Do things the 'manual' way In a world of automatic everything, it is nice do do things the manual way every once and a while. Too much automation can cause you to forget what really happens in the background. Try mounting your flash drive manually, or compiling and installing that latest snapshot from source. Who knows? You might end up needing to do these sorts of things manually if something is not working.
    
7. Write a barebones kernel What better way to understand an OS than to make one yourself! Making a simple kernel is not as hard and scary as many people think it is. Of course, if you want to make your kernel able to do something useful, be prepared to do a lot of reading. Here is a great place to start out with OS programming.
    
8. Read a book on digital electronics It's hard to understand a computer if you don't know how different computer parts can communicate with each other. I highly recommend Digital Electronics Demystified, because it teaches you all the essentials. You can also use this knowledge to build some neat circuits.
    
9. Program a microcontroller This requires a light background in electronics, but programming a microcontroller can be fun and useful. You can program microcontrollers in C or Assembly. You can also make a bunch of neat circuits with it, too.
    
10. Read the book 'Code' This is a really great book about how computers really work. You can find a review of it here.

Just hours ago, Wolfram|Alpha was launched. If you have not been there already, check it out! This revolutionary site was just too exiting for me not to write about it. Wolfram|Alpha essentially makes libraries and libraries of knowledge available at a click of a mouse. Wolfram|Alpha is not a search engine, it is completely different and unique. You won't know it until you try it. This definitely won't replace Google for me, since the two products solve two different issues. Nonetheless, it will definitely be useful for school stuff. I'm not sure if it has much appeal for the normal Internet users, though.

Here is a link to a demo by Wolfram himself.

Enabling searching in Drupal is easy enough, but a lot of people have trouble enabling the advanced searching capabilities in Drupal. Once an administrator enables a search box, he or she will be able to access the advanced search form on the search page. The problem, however, is that normal and unregistered visitors cannot see it.

To fix this problem you need to navigate to Administer -> User Management -> Permissions. Scroll all the way down to the 'search module' section and check the two checkboxes for advanced searching like so:



If you just want registered users to access advanced searching, just check the rightmost box. Well that's about it! Now even non-administrators can use the advanced search in Drupal:

When recently upgrading my server to Ubuntu 9.04, phpMyAdmin was also upgraded to version 5.0.75. When I loaded up the new version, I was alarmed to find a new error message that read:

Connection for controluser as defined in your configuration failed.

It turned out this error was due to the fact that version 5 of phpMyAdmin adds support for a new feature known as a linked-tables infrastructure. This infrastructure allows for new features such as bookmarks, comments, SQL-history, PDF-generation, and field contents transformation. The problem was that this new feature is enabled by default, with generic credentials set up for the controluser. If you don't have your database set up for the infrastructure, you will see the error. I have no use for these new features, so I'd rather just not mess with them. If you do want to enable the advanced features, here is an informative post about doing so on Ubuntu. If you just want to disable the linked-tables infrastructure, which is often the easiest and least intrusive way, just follow these steps:

1. Type nano /etc/phpmyadmin/config.inc.php in the Linux terminal. You can substitute nano for vi or your favorite text editor.
    
2. Find the two blocks of text that read:

   $cfg['Servers'][$i]['controluser'] = $dbuser;
   $cfg['Servers'][$i]['controlpass'] = $dbpass;
   

   one is near the top embedded in an if statement, and the other is towards the bottom. The text is not exactly the same for each block, but $cfg['Servers'][$i]['controluser'] is what matters. The block that is actually used by phpMyAdmin depends on your setup, but just for simplicity we will apply the change to both.
    
3. Just comment out those four lines by adding a // in front of each one.
    
4. Save, and the error should disappear next time you access phpMyAdmin. If you are still having trouble, feel free to post a comment.

Normally when I open a book that explains how computers work, I get little illustrations of the CPU, RAM, hard drive, and graphics chip. This is a great way to educate people about computers, but I have always wondered how computers really worked - from the transistor up.

In Code, Charles Petzold avoids the over simplifications of other books altogether. Petzold starts by explaining the use of Morse code to talk to friends using flashlights, and moves on to relays, logic gates, flip flops. With each chapter Petzold adds another layer to your knowledge. At the end of the book you will understand the inner workings of a computer from the simplest to most complex components. After reading this book, I have all the knowledge I'd need to build a simple computer from the ground up.

One of my favorite characteristics of Petzold's writing is his foolproof explanation and careful attention to detail. As examples, Petzold uses accurate and interesting real world scenarios. A particular favorite of mine was his description of how a barcode works, to help explain the binary system. Because Code explains things from the very lowest levels first and one step at a time, very little previous knowledge of computers is required. I've enjoyed reading this book so much - hopefully you will to! I highly recommend it to anyone wanting to know what really goes on inside the computer.

I might even start and post a project where I actually build a computer from scratch. For the time being, here is a very interesting link to a webpage describing such a project: http://www.homebrewcpu.com/

UPDATE: I published some Logisim implementations of the CPUs described in this book here.