Tutorials in ‘Applications’ Category

How to forbid downloading files with Internet Explorer

Assuming that if a user of a given machine has chosen Internet Explorer as his/her browser, one can conclude that the user is not quite aware of hat he/she is doing. So just to be safe, it may be a good way to prevent the user from downloading any files from Internet if he/she is using IE.
Naturally, to force such a strange behavior we will use a good old registry tweak. First, we will open the Registry. Open the Start menu and enter regedit in the start menu searchbox:

and hit Enter. The Registry Editor will open:

Using the left-hand pane, navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3:

Note: The next step is optional as the value 1803 may already exist.
On the right-hand pane click anywhere except the Name column and select New > DWORD (32-bit) Value:

Name the new value 1803:

Double-click on it and a window will open. Enter 0 in the Value data textbox:

Click OK and close the Registry Editor. To revert to your old settings simply delete the value 1803.
Note: This trick works for IE 6 through 9.

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Disable favicons in Firefox

Favicons are the little icons that appear on each tab in your browser. Although they can help you find which site you have opened in a given tab, when you have a lot of tabs opened, they can really, really annoy you if the site designers have decided that a blinking favicon is the way to go. That is why, Firefox allows users to disable favicons in a rather easy way.

Open Firefox and enter about:config in the address bar. Firefox will warn you that you can really mess things up if you are not careful.

Click the I’ll be careful, I promise! button and the configurations will open:

In the Filter textbox enter browser.chrome.favicons:

Double click on the browser.chrome.favicons preference to set its value to false:

Do absolutely the same for the browser.chrome.site_icons preference:

Restart Firefox and you are done.

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Creating host-specific PuTTY shortcuts

When using PuTTY with multiple hosts and/or with multiple sessions, there is always the problem of entering the same information many, many times. Now, you can always go for the key-based SSH login with PuTTY, which is a secure way of doing this, but here, we will present you an easier and simpler way of auto-login using PuTTY shortcuts.

First, you must obtain a copy of the PuTTY client (available here). Now, after downloading it, open PuTTY:

In the Host Name field enter the name of the host, set the port in Port and enter a name for the session in the Saved Sessions text field:

Click Save to save your profile. Now when you double-click on the entry in the Saved Sessions or click on it, click Load and click Open your PuTTY client will automatically connect to it. You can save every host you like in the Saved Sessions:

Now here is the really nice part. Create a shortcut to PuTTY and open its Properties:

Now after the current Target (after the if any, and don’t forget a space), you can add a few arguments to automatically log into a saved session. The possible arguments are:

-load “<session_name>” – for automatically loading a session. Note: <session_name> is a saved session name and not a hostname.

-l <username> – for automatically entering a username on the host.

-pw <password> – for automatically entering a password.

Note: Using the -pw option is not secure in any way. If you use it you are storing your password in plain-text. If you have any doubts about how secure your machine is, please refer to the key-based SSH login.

It is also possible to only use some of those arguments, so for example if you want to load a session and a username you can only use the -load and -l options. Or if you use the same credentials for more than one host (which is bad, bad, bad…), you can omit the -load option. So, an automatic login on the host specified in the session ABlog with username root and password badandtrivial will be:

“D:\<path_to_putty>\putty.exe” -load “ABlog” -l root -pw badandtrivial

Note: This method is not in any way secure. It is merely a method to speed up your work, but stores passwords in plain-text.

So after editing a shortcut’s properties you only click OK to save. You can easily have multiple shortcuts:

Still, secure or not, it can be used for any non critical information. It is not, in any way, more dangerous than storing passwords in browsers…

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Creating and signing certification requests using OpenSSL

In our previous tutorial about creating your own Certificate Authority, we introduced OpenSSL – an open source commercial-grade toolkit, which implements SSL and TLS (Secure Sockets Layer and Transport Layer Security) and provides a general purpose cryptography library. Naturally we continue with creation of certification requests (also called Certificate Signing Request).

Note: In this tutorial (as well as in the previous one) we assume CentOS is the OS of choice.

To create a certificate request we navigate again to /etc/pki/CA:

cd /etc/pki/CA

Now let’s create the certification request. We’ll request a certificate, which will last one year:

openssl req -config openssl.cnf -new -nodes -keyout private/<domain>.key -out <domain>.csr -days 365

Generating a 2048 bit RSA private key
..............................+++
.................................+++
writing new private key to 'private/<domain>.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [XX]:<country>
State or Province Name (full name) []:<state>
Locality Name (eg, city) [Default City]:<city>
Organization Name (eg, company) [Default Company Ltd]:<organization>
Organizational Unit Name (eg, section) []:<department>
Common Name (eg, your name or your server's hostname) []:<url>
Email Address []:<email>
 
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

This creates two files, <domain>.key, which is the private key and <domain>.csr, which is the Certificate Signing Request. Restrict the rights to the private key so it readable only by root and the user that will use it:

chown root:globus private/<domain>.key

chmod 0440 private/<domain>.key

So now that we have created the certification request it is time to sign it. Navigate to /etc/pki/CA:

cd /etc/pki/CA

Sign the certificate using this command:

openssl ca -config openssl.cnf -policy policy_anything -out certs/<domain>.crt -infiles <domain>.csr

Using configuration from openssl.cnf
Enter pass phrase for ./private/ca.key:<ca_password>
Check that the request matches the signature
Signature ok
Certificate Details:
        Serial Number: 1 (0x1)
        Validity
            Not Before: Nov 15 18:52:08 2011 GMT
            Not After : Nov 14 18:52:08 2012 GMT
… CERTIFICATE INFORMATION …
Certificate is to be certified until Nov 14 18:52:08 2012 GMT (365 days)
Sign the certificate? [y/n]:y
 
 
1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated

After that, you need to remove the certificate request:

rm -f <domain>.csr

After the whole procedure two files are created. <domain>.crt – this is a domain specific certificate for the request. It is put in the certs directory. <certificate_number>.pem is the second file. It is put in the newcerts folder. This is a ready to use X.509 file which contains the information from <domain>.key and from <domain>.crt.

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Create your own Certificate Authority using OpenSSL on CentOS

OpenSSL is an implementation of the SSL and TLS protocols. It is open-source and is the de-facto standard toolkit for Secure Sockets Layer (SSL) and Transport Layer Security (TLS). It is written in C and also contains a general purpose cryptography library. Being written in C allows for various wrappers for other programming languages to exist.

Installing OpenSSL on CentOS is actually quite easy. All you have to do is enter the following command:

yum install openssl

Note: Depending on your installation configurations OpenSSL may already be installed on your system.

Note: This tutorial uses OpenSSL 1.0.0.

After we install OpenSSL, we need to setup our own Certificate Authority. To do so we first navigate to /etc/pki/CA:

cd /etc/pki/CA

Now we will make a directory where our certificates will be stored:

mkdir certs

Another necessary directory is for the revocation list:

mkdir crl

Note: crl stands for Certificate Revocation List.

Now we must create a directory for storing the unencrypted certificates:

mkdir newcerts

Next, create an empty file index.txt (you may use touch). The index.txt file is the database for certificates. Additionally, create two files containing the next serial number for a certificate and the next serial number for the revocation list:

echo ’01’ > serial

echo ’01’ > crlnumber

Almost ready. Copy the standard openssl config file to you current directory:

cp /etc/pki/tls/openssl.cnf openssl.cnf

And edit the config file (the one stored at /etc/pki/CA/openssl.cnf):

Change this line:

dir             = /etc/pki/CA           # Where everything is kept

to

dir             = .           # Where everything is kept

Change this line:

certificate     = $dir/cacert.pem       # The CA certificate

to

certificate     = $dir/certs/ca.crt       # The CA certificate

And this line:

private_key     = $dir/private/cakey.pem# The private key

to

private_key     = $dir/private/ca.key # The private key

And last, but certainly not least, make /etc/pki/CA/openssl.cnf readable only for you:

chmod 0600 openssl.cnf

After that, the process of creating a certificate authority is actually quite easy. Navigate to /etc/pki/CA:

cd /etc/pki/CA

Enter the following command:

openssl req -config openssl.cnf -new -x509 -extensions v3_ca -keyout private/ca.key -out certs/ca.crt -days 3650

if you want to create a CA valid for 10 years. You will be prompted:

Generating a 2048 bit RSA private key
........+++
.......+++
writing new private key to 'private/ca.key'
Enter PEM pass phrase:<password>
Verifying - Enter PEM pass phrase:<password>
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [XX]:<country>
State or Province Name (full name) []:<state>
Locality Name (eg, city) [Default City]:<city>
Organization Name (eg, company) [Default Company Ltd]:<organization>
Organizational Unit Name (eg, section) []:<department>
Common Name (eg, your name or your server's hostname) []:<common_name>
Email Address []:<email>

Where common_name is usually formed like ca.<your_domain>, and <email> is usually ca@<your_domain>

Finally, don’t forget to restrict the access to your private key:

chmod 0400 private/ca.key

For more on OpenSSL checkout how to create and sign certificates.

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Add Color To Black And White Image Photoshop Tutorial

In This Photoshop Tutorial Add Color To Black And White Image easily .this is very interesting photoshop tutorial easy to add color to black and white image in Photoshop few steps tutorial.

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How To Making Text photo In Adobe Photoshop Tutorial

How To Making Text photo In Adobe Photoshop Tutorial,In this Adobe Photoshop tutorial we are going to learn how to replace an image in text effect

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Record sound with Microsoft Sound Recorder

Using Microsoft Sound Recorder, you can record, mix, play, and edit sounds.

To record sounds, your computer must be equipped with a microphone. Recorded sounds are saved as waveform (.wav) files. Read the rest of this entry »

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Making my home movies in Windows Movie Maker

Windows Movie Maker is video editing software that is included in Microsoft Windows XP operating system. It offer functionality such as transition effects, filters, audio track, timeline narration.

For this tutorial we will use default Windows Movie Maker sample videos included in Windows XP. Read the rest of this entry »

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Editing images with IrfanView

IrfanView is small and very powerful software program for viewing, editing, converting, printing, scaning images. Read the rest of this entry »

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