1. Adblock Plus

Adblock Plus is an extremely popular extension. Most of you know about Internet advertising and the abundance of ads on some websites (see – even we have some ). A lot of these advertisements are mostly harmless, however, it’s a good idea to block the ads for many reasons. First is obviously for security. No matter how many times you tell people not to click ads that look suspicious (winning lottery, hot girls waiting for you, you are the millionth customer, etc), they still do it. Almost all such ads contain some security threat – phishing, malware, spyware, viruses. They are not safe. Another reason is if you have kids – even the supposedly safe sites these days can pop-up with X rated advertisements. Having a protection against them is very important.

This is where Adblock Plus comes in. Simply put it will remove all advertising content from web pages and will deliver only pure content to you. It’s the best no-nonsense extension out there. Because the pages no longer load ads, the browsing speed improves quite a lot – especially if you use slow connections. We strongly recommend this add-on to all users of Firefox. The extension can be downloaded and installed from here.

2. Video Download Helper

We are often faced with situations where we want to download embedded content from websites. You tube videos for instance. Many people don’t know how to download such content. There are some dedicated websites that convert the URL into direct download links but where most of those services work on one or two sites, video download helper works on many.  It sits near the address bar in Firefox and whenever it detects embedded media – audio, video and images, it gets activated and you can see 3 spinning balls. Clicking on that icon will list all the embedded media available on the page, which you can now download without having to go look for any other website that converts the links. You can find the download link and more details here.

3. StumbleUpon

StumbleUpon is a great tool if you have dried up on ideas. It’s a website where you can browse websites matching your interest. There are 500 topics to chose from and users like you tag the websites and pages with the topic. All you do is create an account, the toolbar (this add-on) has menus that you can use to chose a topic or a tag – click the stumble button and you’ll be browsing through the topics you chose. You can also browse through similar topics on the same website as well. It also gets better as you tag more websites and browse more. With over 25 million registered users and more than a billion stumbles per month, this is one of the best add-on for writers and researchers. It’s database it ever growing and is getting better every day. You can get it here.

4. Greasemonkey

Getting annoyed by the Facebook ticker that was added recently? Use Greasemonkey. Greasemonkey allows you to use scripts that allow on-the-fly changes to web pages. There are plenty of scripts available that you can use to make changes, there is no need to worry if you don’t know how to write the scripts. The best thing is, Greasemonkey remembers these changes and will execute them every time you load the page. It’s as if the website has changed – just for you. There are, as I said, a lot of user scripts available on userscripts.org. You can also roll out your own scripts, look at the wiki for information on how to do this and finally you can get the add-on here.

5. Feedly

Feedly is the overall best start-page add-on I have ever seen. Remember iGoogle? It tried to organize all your content on one page which you can put as your default start page for your browser. Feedly is similar to that but much better. Feedly is magazine-like start page based on the best content of your favorite websites. Powered by Google Reader and Twitter. When installed Feedly will present you with a starting page that has news from a variety of topics such as Android, Photography and World News. You can customize all of this, add sites you want to follow and also read your Google reader feeds right here. You can also log-in to your twitter and Facebook feeds to check them from Feedly. It also comes with a link to this article telling you 9 ways to personalize your Feedly page. You can download the add-on here.

The command used to modify file permissions is chmod, short for change mode of a file. You can also use Nautilus file browser to change the file permissions. I will cover the details after a little background on the file permissions. To find the permission settings for a file, issue the following command int he terminal from the directory where your file is.

ls -l
cmd output

As you can see, the first column in the output has some strange looking character sets. This set is the file permissions for that file (directory). The third column is the owner of the file (directory) and the fourth column is the default group of the file (directory). We can ignore all the other columns at this point.

In the first column, each set would be 10 character wide. The very first character is a d for a directory or just a - (hyphen) for files. After that, the next three characters are the permissions for the owners account. The order is read-write-execute. If the superuser can read the file it would display r otherwise just a -. Similarly for write and execute w and x would be displayed. The next three characters are permissions for all the other users belonging to the file group (from the fourth column in the output above). Final three characters are the permissions for everyone not part of the group. Superusers (root accounts) can always override all the settings mentioned here and none of the permissions apply to them.

Changing Permissions – The Easy Way

The easiest way, as I said, is to just change the file permissions using Nautilus but it’s time consuming if you want to change the permissions of a lot of files. Command line way may seem tedious to begin with but it’s the faster way once you know your way around. To change the permissions in Nautilus, right click on any file (directory). Go to properties and then to permissions. Change the permissions and click ok. That’s it.

Changing Permissions – The Faster Way

To change file permissions via the terminal, you can use the chmod command. To change permissions of a file, enter the following command in the terminal.

chmod ABC path/to/file

Here, ABC is a 3 digit number which is the decimal representation of the file permissions. For example, r-x means 101 in binary which translates to 5 in decimal. So, if you want everyone to have just read and execute access to files and only the owner has the write access to files then the permissions are rwx,r-x,r-x which is 111,101,101. That translates to 7,5,5 (comma is only given for clarity here). So, the command would now be,

chmod 755 path/to/file

Don’t worry if you don’t know how binary works, you will get used to it. Easiest way is add 4 for read, 2 for write and 1 for execute. So, considering the examples above, rwx = 4 + 2 + 1 = 7 and r-x = 4 + 0 + 1 = 5. You’ll get used to this. There is another way to to this, the text method (which I don’t prefer).

chmod who=permissions filename

Where Who is any from a range of letters, and each signifies who you are going to give the permission to. They are as follows:

u - The user that own the file.
g - The group the file belongs to.
o - The other users i.e. everyone else.
a - all of the above - use this instead of having to type ugo.

And then you can directly write rwx in front of the equal sign. For example,

chmod g=rx

Next post will cover setting default permissions to files you create using umasks.

One of the great features of Facebook is the birthday reminders. Let’s face it – there are many of us who aren’t very good at remembering birthdays. This habit of forgetting can be dangerous (especially if you have a girlfriend/wife). To avoid any injuries, mental stress and a lot of mess – Facebook has given us this extremely important feature of birthday reminders.

However, there is a problem that many people don’t want to reveal their birthday (me for example) mainly because of identity theft issues. This makes things a little difficult since you don’t get all the notifications at the same place now. A solution? Use google calendar or iCal or any other application where you can add birthdays and get reminders (you have to know the date of course).

I began using Google Calendar to keep track of birthdays even before Facebook. At that time I used to manually enter every birthday. This makes things a bit time consuming, especially if you have multiple hundred friends. The solution? Use the export feature in Facebook. Here’s how,

Click on the events tab on the left panel.

Events List

Now on the center pane you would get a list of all the birthdays. Scroll to the bottom of the page where you will see an Export Birthdays link. It would open a dialog that looks like this,

Export Birthdays

Copy this link, now open Google calendar and click on the Add by URL,

Add By URL

This will add a new calendar to your Google calendar. You’re done except for one part. You need to set the reminders for the calendar. To do that go to settings ? calendar settings ? calendars ? Friend’s Birthdays. Click on notifications and set the type of notifications.

You’re done. You can do this for any other application that supports iCal format calendars also. Now there’s an application which might just save you from a breakup

Today’s gaming industry is growing wildly. With the advent of MEMS Systems – all those Accelerometers, Gyroscopes and the likes – the gaming today is taking a more natural interface than ever before. Now you can just swing the remote and hit a ball, tilt your phone and the car just skids across the screen. It’s more natural, more realistic, and to me – it’s boring at times.

There used to be a time when I used to enjoy gaming. Spend 5-6 hours a day playing the same game again and again till I could finally complete it. Let’s face it – the old consoles and the games were just more funny than what they’ve become today. I found myself longing for the old days. I no longer have access to my console. It’s in safe custody of my parents back home. What I do have though is DOSBox. DOSBox is an open source DOS emulator that runs across various operating systems. You can download DOSBox for your operating system from here.

If you open DOSBox you will be greeted with the drive letter Z, which is the default DOSBox prompt that looks something like this.

DOSBox

As you can see DOSBox by itself is a command line program but there are a number of frontends available that you can use to improve the usability. I prefer DBoxFE – it’s cross platform and is designed with gaming in mind.

DBoxFE

As you can see in the image (please check the full size for details), you can tweak a lot of options using the frontend. You can also make profiles and save different states. There are a number of games that have been tested to successfully work on DOSBox. A few of them include,

• Dave
• Aladdin
• Prince
• Commander Kin
• Discworld
• Doom
• Wolfenstine

For a full list of compatible games, head over here. I particularly enjoyed playing Discworld on DOSBox. Of course, I also finished Dave a few times and enjoyed my way through prince megahitting the enemies and yippeeyahooing at the same time.

Discworld

But that’s not all folks. DOSBox isn’t just another gaming system. It’s a (almost) full fledged emulator for DOS. You can install numerous applications, even a Windows 3.1 installation can be done under it. It can emulate multiple audio-video drivers, can access the optical drive of the host machine.

The latest versions of DOSBox also have a built in video recorder. To record a movie, you have to press CTRL-ALT-F5. To stop/end the recording, you have to press CTRL-ALT-F5 again. The video is an exact replica of what you do on DOSBox.

With DBoxFE, you won’t have to worry about the commands. Most of the options and fields in DBoxFE are self explanatory so I won’t spend much time educating you in the use of command line. It rocks – but I guess you would be bouncing up and down with excitement at the thought of playing those 256 color games… too dramatic? Well… Happy Gaming

Internet is growing faster than it has ever been. As more and more people use, develop and deploy their applications on the Internet, the threat of spammers and bots is also increasing at an alarming rate. CAPTCHA tries to minimize the spamming problems encountered by most developers.

CAPTCHA stands for Completely Automated Public Turing to tell Computers and Humans Apart. Almost everyone familiar with the Internet has seen CAPTCHA at a lot of places. Yet, for those of you who do not know, this system generates images containing letters and numbers. You, as a human, can easily identify the contents of the image and have to enter them in an input box to verify you are not a bot. Sounds cool huh? But how do you use this on your sites and in your applications? Here’s a list of the best CAPTCHA services that you can use in your projects,

1. reCAPTCHA

reCAPTCHA

reCAPTCHA is probably the most well known service being used my over 30 million sites every day. Supports PHP and yes – works very well with WordPress. It is a free CAPTCHA service that helps to digitize books, newspapers and old-time radio shows. reCAPTCHA improves the process of digitizing books by sending words that cannot be read by computers to the Web in the form of CAPTCHAs for humans to decipher, now how cool is that!

2. Akismet

akismet

Akismet is probably best known amongst wordpress people. It comes pre-installed on wordpress and you can let it do it’s work and relax. It successfully catches over 90% spam.

3. wp-captcha-free

wp-captcha-free

WP Captcha-Free generates a hash (aka token) based on several parameters like time (with a some cushion), post id, IP address, and browser user-agent which should not change between requests (within a short period of say a few seconds). When the comment form is posted the plugin uses ajax to get a hash value and adds it to a hidden field. On the server side it verifies if the hash is valid or not. It uses adds random salt to the hash so that it cannot be guessed.

4. Text Disguise

Text Disguise

Simply put, Text Disguise is a Human Interactive Proof. What is a Human Interactive Proof? It is a method of telling human users apart from computers (or, also known as “bots”). By presenting a CAPTCHA-image to a user, it requires that a living, breathing, thinking person be at the keyboard – interacting with your web site.

5. Secureimage

Secureimage

Securimage is an open-source free PHP CAPTCHA script for generating complex images and CAPTCHA codes to protect forms from spam and abuse. It can be easily added into existing forms on your website to provide protection from spam bots. Securimage does everything from generating the CAPTCHA images to validating the typed code. Audible codes can be streamed to the browser with Flash for the vision impaired.

6. Defensio

Defensio

More than just another spam filter, Defensio also eliminates malware and other unwanted or risky content to fully protect your blog or Web 2.0 application.  It takes aim at threats to social media, such as malicious content, comment spam, and other embedded threats.

7. Mollom

Mollom

Mollom is a web service that helps you identify content quality and, more importantly, helps you stop spam on your blog, social network or community website. When site moderation becomes easier, you have more time and energy to interact with your community.

Often times Linux users find themselves wanting more from the network manager, especially laptop users on the move find it difficult to manage all the different networks they have access to. WiCD is one of the best tools for people wanting more. It’s gtk based network configuration tool, especially meant for wireless networks written in python. Apart from being dependent on gtk, it does not require any of gnome components to work. Rejoice all the openbox and fluxbox users.

Here’s what WiCD can do (taken from the official documentation),

1. Compatible with standard *nix networking commands (iwconfig, ifconfig, etc)
2. Once configured, will connect even if the X display does not start
3. Can be managed and configured via the command line using wicd-curses
4. Support for wired networks, as well as named profiles to save multiple wired configurations.
5. Supports configuring static IP addresses and DHCP on a per network basis
6. Store different static IPs, gateways, subnet masks, DNS server addresses per network
7. Automatically connect at boot – no user intervention required, even for encrypted networks
8. Keeps network keys in root accesible only (600) files (unencrypted, however)
9. Encryption (template based)
   1. WPA 1/2
   2. WEP
   3. LEAP
   4. TTLS
   5. EAP
   6. PEAP
10. Automatically connects at resume from suspend
11. Displays information about the network
12. Ability to run scripts before/after connecting/disconnecting

All this and it’s really easy to use. Let’s start by installing WiCD, if you are an Ubuntu user, you can install WiCD very easily. All you need to do is open a terminal and issue following command,

sudo apt-get install wicd

This will install both WiCD with all the required dependencies. It will then ask you for the users you want to configure WiCD for. WiCD also comes with a tray icon. You can add it by right clicking a panel and choosing add to panel option then choose custom application launcher. Give it any name you want and in the command box type,

/usr/bin/wicd-gtk

and you will have a tray icon now. Open WiCD and you will be greeted with a screen showing all the wireless networks in the range. You can then chose to connect to any network you want. If the network is protected by any security then you would have to chose the method of security in place and enter the correct key to connect to the network.

WiCD Networks

You, of course, also get the option to chose whether to use DHCP or static IPs, which DNS you want to use, which secondary DNS you want to use. gateways, subnet masks. You can also use it to manage wired networks.

WiCD Advanced

And there’s more…

WiCD Advanced 2.0

I for one have never had any problems with WiCD., although there are people who report certain incidents, it’s free from most major bugs and is a very solid program. One of my favourite distributions, Zenwalk, comes with WiCD pre-installed. Rest assured, this is a great tool to manage all your moving connection needs.

SysRq

It doesn’t happen quite often but when it does – it’s a pain in the… Nevermind that, I am of course talking about system freezes on Linux. Freezes are rare but if you are like us and install, use and test beta versions of software or operating systems themselves, there is a significant chance you will end up with system crashes, freezes, kernel panics. Most people have no idea that hitting the power button is not the only option. You are likely to compromise the filesystem integrity by doing so. This is where the SysRq key comes in.

Chances are, the kernel you are using has been compiled with a flag CONFIG_MAGIC_SYSRQ when compiled. If it is – you can breathe easy because this enables you to reboot system, recover from freezes without damaging the filesystem. You can forcibly unmount file systems, kill processes, recover keyboard state, and write unwritten data to disk.

The combination is Alt, SysRq key and a third key which changes with each command. If you don’t have a separate PrtScr and SysRq keys then most probably this won’t work for you as only a screenshot would be generated. To avoid this Print Screen feature the magic SysRq combination should include the Ctrl, becoming ‘Ctrl’+'Alt’+'SysRq’+key. Some common key-binding are given below.

• ‘k’ – Kills all the process running on the current virtual console.
• ‘s’ – This will attempt to sync all the mounted file system.
• ‘b’ – Immediately reboot the system, without unmounting partitions or syncing.
• ‘e’ – Sends SIGTERM to all process except init.
• ‘m’ – Output current memory information to the console.
• ‘i’ – Send the SIGKILL signal to all processes except init
• ‘r’ – Switch the keyboard from raw mode (the mode used by programs such as X11), to XLATE mode.
• ‘s’ – sync all mounted file system.
• ‘t’ – Output a list of current tasks and their information to the console.
• ‘u’ – Remount all mounted filesystems in readonly mode.
• ‘o’ – Shutdown the system immediately.
• ‘p’ – Print the current registers and flags to the console.
• ‘0-9’ – Sets the console log level, controlling which kernel messages will be printed to your console.
• ‘f’ – Will call oom_kill to kill process which takes more memory.
• ‘h’ – Used to display the help. But any other keys than the above listed will print help.

You can also access this feature from the command line directly (as root, of course) by following command,

echo b > /proc/sysrq-trigger

This is similar to pressing the combination of Alt+SysRq+b which reboots the system. There are some cases when you want to disable this feature. You can do so with,

echo 0 > /proc/sys/kernel/sysrq

On newer kernels (exact version unknown), it is possible to have a more fine-grained control. On these machines, the number written to /proc/sys/kernel/sysrq can be zero, one, or a number greater than one which is a bitmap indicating which features to allow.

Possible values are:

• 0 – disable sysrq
• 1 – enable sysrq completely
• >1 – bitmask of enabled sysrq functions:
  • 2 – control of console logging level
  • 4 – control of keyboard (SAK, unraw)
  • 8 – debugging dumps of processes etc.
  • 16 – sync command
  • 32 – remount read-only
  • 64 – signalling of processes (term, kill, oom-kill)
  • 128 – reboot/poweroff
  • 256 – nicing of all RT tasks

Finally – in order to perform a safe reboot when you are frozen or stuck at a point. The command is unraw, terminate, kill, sync, unmount, reboot.

UPDATE – You can also use ‘i’ instead of ‘k’ in the sequence mentioned above. It does not kill the init process. Also – an easier way to remember this sequence is busier in reverse order. Remember the reverse order or you would end up rebooting the system which is useless for this purpose.

Internet Censorship Map

Every packet that leaves your computer has a header containing your host IP address and the destination IP address. Even if the data (payload)  is encrypted, the header is not. This traffic analysis can lead to the attacker (which is your ISP / Government most of the times) getting hold of a multitude of information about you. The originating country, the date, time, which browser you use. Apart from identity theft, potential information leak – your location, browsing habits, your work can be in danger. The map on the left shows the countries where the government forces the ISPs to censor data and keep checks on the traffic. This, though not very dangerous, can lead to legal action against the users if they are doing something the government does not want them to do. Even if you have a dynamic IP address – you can still be tracked. This is where the TOR network comes in.

Tor network uses a distributed network of nodes – of other TOR users – to re-route all the packets from your network. What this means is – no single link can identify the source and the destination. To create a private network pathway with Tor, the user’s software or client incrementally builds a circuit of encrypted connections through relays on the network. The circuit is extended one hop at a time, and each relay along the way knows only which relay gave it data and which relay it is giving data to. No individual relay ever knows the complete path that a data packet has taken. The client negotiates a separate set of encryption keys for each hop along the circuit to ensure that each hop can’t trace these connections as they pass through. The 2 images, taken from the official tor website, below show this process. The first image is how the network (plausibly) works and the second image depicts it after using the tor network.

How Tor Works

How Tor Works

Even with all this, Tor is not very safe. There are potential pitfalls and security threats. Tor by itself does not encrypt the payload and a sniffer at the exit node (as you can see in the image) can get all the data without any encryption present at the TCP layer. Unless the application encrypts data (SSL), a sniffer at the exit node can gather information. Tor does not work on UDP sockets for now. Tor is not designed to work with P2P networks as well.

It is however better than having nothing. To install tor, download the appropriate package from the tor website. The install instructions for various Linux distributions change however, for a general procedure, please head over to the Tor blog. Windows users can check the video below and get everything running.

Happy Browsing.

All you need to do is issue the following command,

wget -c -r --level=0 --no-parent -k -p http://noob2geek.com/someDirectory

Where, the flags mean the following,

• -c
  • Continue download (in case of resuming download)
• -r, –recursive
  
  • Recursive download.
• -l, — level=NUMBER
  • Maximum recursion depth (inf or 0 for infinite).
• – no-parent
  • Do not download parent files.
• -k, –convert-links
  • Change link paths to relative.
• -p, –page-requisites
  • Get all objects (such as images) referenced by the HTML page.

That’s it – Happy downloading, may your collection grow enormously huge!

OKay, I admit I went a bit too far here. We will concentrate on installing Windows applications on Linux in this tutorial. You will need following things

• A computer with Ubuntu Linux installed (Any Linux distribution would be fine, but this tutorial is based on Ubuntu 10.10).
• Administrative (root) access.
• Internet access.
• Moderate to Lower-High patience

Now, we will first be installing the application called Wine. Wine stands for Wine Is Not an Emulator. Think of it as an open source implementation of the Microsoft API (Application Program Interface).

Unless the program you wish to install is a peculiar one, you probably will not face problems with Wine, however, it’s still best to check with the Wine database at appdb.winehq.org and check the status just in case.

Installing Wine

Once you have satisfied yourself we can move on to installation of Wine on Ubuntu. Open the Software Sources menu by going to System > Administration > Software Sources. Then select the Third Party Software tab and click Add.

Installing Wine on Ubuntu

Click on Add Source, refresh the package list and then head over to Applications ? Add/Remove and search for Wine and install it. Alternatively, you can also do this from the command line by

sudo add-apt-repository ppa:ubuntu-wine/ppa
sudo apt-get update
sudo apt-get install wine

Whichever method you opt for, install Wine because that’s what we are here to do.

Configuring Wine

Before using Wine, it is necessary to create the pseudo C:\ drive where your Windows applications will be installed. Enter Wine configuration mode by issuing following command on your machine,

winecfg

You can also select the Configure Wine option in the Applications ? Wine menu. This will create the .wine directory in your home directory. This is used to store all the configurations and the pseudo C drive. It also contains a bunch of other things including but not limited to the registry structure like that in Windows, configurations settings like the Windows version to be emulated, DLL overrides and specific memory related settings. We don’t need to go into the details of those at this moment.

Installing Applications

To install Windows applications with Wine, follow the instructions below,

1. Download the Windows application you wish to install and place it in a convenient directory.
2. Open the terminal on your system.
3. Change to the directory where the application installer is located.
4. Issue the command wine followed by the name of the application to install it.

e.g.:

wine someApplication.exe

Remember to give the full name of the application along with the extension.

Running the Wine applications

Most application installed via Wine will end up in a special Wine menu in your main menu and you can directly launch those applications from there.

Uninstalling the applications

To uninstall the applications, open up a terminal and type “uninstaller” – this will open up a program which lets you uninstall applications from Wine. Running uninstall programs directly via Wine should also work normally. Alternatively, you could also simply delete the folder of the application but it leaves traces of that application behind in the registry and other configuration files.

That’s it for now folks. We will take a look at Wine configuration in detail in our future posts.