FIX .jar extension default application for Java

After installing some software which change the default application for .jar file it becomes difficult to restore the previous state.It can be fixed as described below:
Create a .reg file following content and then run the file:

Windows Registry Editor Version 5.00



[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.jar]



[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.jar\OpenWithList]



[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.jar\OpenWithProgids]

"WinRAR"=hex(0):

"jarfile"=hex(0):



[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.jar\UserChoice]

"Progid"="jarfile"

UPDATE INTERNET DOWNLOAD MANAGER (IDM) ADDON

After updating Firefox, generally the older version of idm addon doesn't work and it is disabled by the firefox.One solution is to update the addon from here.

Mark all Unread mails in gmail as Read

1. Go to your Settings/Filters page and create a new filter.
2. In the Has the words field enter “is:unread” (without quotes), and click the Next Step button.
3. You’ll get a message warning you that this type of filter won’t be applied to new mail, but that’s OK.  Click OK to continue.
4. Check the boxes next to Mark as read and Also apply filter to … conversations below.
5. Click Create Filter button, and you’re done.  You should delete the filter once you finish since it won’t be needed anymore.

Change Login Screen in Fedora 14

Code:

su
(provide the root password)

cp /usr/share/backgrounds/laughlin/default/wide/laughlin.png /usr/share/backgrounds/laughlin/default/wide/laughlin.png.original

cp /usr/share/backgrounds/laughlin/default/standard/laughlin.png /usr/share/backgrounds/laughlin/default/standard/laughlin.png.original

cp /usr/share/backgrounds/laughlin/default/normalish/laughlin.png /usr/share/backgrounds/laughlin/default/normalish/laughlin.png.original

cp /current/file/location/filename1.png /usr/share/backgrounds/laughlin/default/wide/laughlin.png

cp /current/file/location/filename2.png /usr/share/backgrounds/laughlin/default/standard/laughlin.png

cp /current/file/location/filename3.png /usr/share/backgrounds/laughlin/default/normalish/laughlin.png

Note: filename1,filename2,filename3 can be a single file or different files with different dimensions according to the requirement.

Auto mount drives in Fedora

Open a gnome-terminal window and type
su
(provide the root password)

Code:

cd /usr/share/polkit-1/actions && cp -p org.freedesktop.udisks.policy org.freedesktop.udisks.policy_original

(it is always advisable to save the original copy of any configuration file before modifying it).

Next, still as a superuser, open in a text editor following file

/usr/share/polkit-1/actions/org.freedesktop.udisks.policy


and find the block of text containing the line:

    <description>Mount a system-internal device</description>

On Fedora 14, this is the third block from the top (the first is the header, the second is the «Mount a device» block). A few lines below in the same block you will find the line:

      <allow_active>auth_admin_keep</allow_active>

Modify it as follows:

      <allow_active>yes</allow_active>

Save the changed file and exit the editor.

The change takes effect immediately: no need to log out or reboot.

Run CMD Commands Through C program

Here  is the required format of the C program;
#include<windows.h>

void main()
{
 system("cmd.exe /c <command> ");
}

Tracking the Location of An Email Sender

Sometimes it seems essential to track the location of the person who send you an email. To find if the email came from a genuine sender or not… To get some of the background details or the GEO details of the person.

In Gmail or any other email client, when a person send you an email, there is always more information at your disposal then actually that is on surface. To know more information, we need to dive into an email header. Along side the Reply button there is a dropdown option of Show Original. When you click this an original message with all details and email header is shown to you.

In this header text of email (CTRL + F) the text Received: from . It is of utmost importance to know the details of sender. In front of this field the public IP address or the smtp address of the sender is mentioned. The IP address is mentioned like [ xxx.xxx.xxx.xxx].


After you have this public IP address of sender, you can now actually do a Reverse IP lookup or a Reverse Email Lookup.

Below are some of the tools to do this lookup:

1. Visual Trace route Tool : This tool helps you do that and much more visually http://www.yougetsignal.com/tools/visual-tracert/. You just need to enter the IP address mentioned in square brackets. It will then show you each and every IP address and locations through which the Email has traversed on map.
2. Facebook : You can also track the sender by doing reverse email lookup in facebook. Just type in the email ID of sender in facebook search and if you are lucky you will find his/her profile page.
3. IP2Location : This is a webapp for tracking the info like Country, State, City, Latitude, Longitude and ISP
4. GEOBytes : Its also a Reverse IP lookup program that get many useful pieces of information from the IP location.

Apart from these ways you can also search for sender’s email address in google search. From there you may find person’s social profiles, websites and many other thing

Vidalia Proxy error in Fedora.

After installing Viadalia Fedora it seen that the proxy "127.0.0.1:8118" doestnot work
The main reason is that the proxy application polipo don't run automatically in Fedora.
Polipo has to be configured manually as follows:
1.Replace the content of file "/etc/polipo/config"  with this.

2.Open the Settings window of Vidalia
3.In the General tab enable the checkbox to start a proxy application when Tor starts.
4.Add following line in the space provided
    /usr/bin/polipo
5.In Proxy Application Arguments: add following line
    -c "/etc/polipo/config"

6.Done

NS2 Installation on Fedora 15

1.Before your ns-2 installation following packages must be already installed:
(Type these commands in terminal)
yum install tcl-devel
yum install autoconf
yum install automake
yum install gcc-c++
yum install libX11-devel
yum install xorg-x11-proto-devel
yum install libXt-devel
yum install libXmu-devel


2.Some errors Encountered in Installation with solutions:

.1 Errors relating to GammaRandomVariable.
solution:
Following files need to be edited(in Fedora) for successful installation.
 1.    ~/ns-allinone-2.34/ns-2.34/mobile/nakagami.cc

   In line number 183 replace-
     resultPower = ErlangRandomVariable::ErlangRandomVariable(Pr/m, int_m).value();
     with    resultPower = ErlangRandomVariable(Pr/m, int_m).value();
       
    In line number 185 replace-
      resultPower = GammaRandomVariable::GammaRandomVariable(m, Pr/m).value();
      with    resultPower = GammaRandomVariable(m, Pr/m).value();

 2.   ~/ns-allinone-2.34/ns-2.34/tools/ranvar.cc
       
   In line number 219 replace-
   return GammaRandomVariable::GammaRandomVariable(1.0 + alpha_, beta_).value() * pow (u, 1.0 / alpha_);
  with   return GammaRandomVariable(1.0 + alpha_, beta_).value() * pow (u, 1.0 / alpha_);

2. Error with following lines:
mac/mac-802_Ext.h:In member function 'u_int32_t PHY_MIBExt::getHdrLen11()':
mac/mac-802_Ext.h:175:19: error: expected primary-expression before 'srtuct'
mac/mac-802_Ext.h:175:41: error: 'dh_body' was not declared in this scope
mac/mac-802_Ext.h:175:51: error: 'offsetof' was not declared in this scope
mac/mac-802_Ext.h:177:3: warning: control reaches end of non-void function [-Wreturn-type]

Solution:

Include the header file "stddef.h" in  the file ~/ns-allinone-2.34/ns-2.34/mac/mac-802_11Ext.h


3. error while loading shared libraries: libotcl.so: cannot open shared object file: No such file or directory

Solution:
The environment variables need to be set. An example is as shown (edit Path according to your system)
export PATH=$PATH:/home/unicorn/ns-allinone-2.34/bin:/home/unicorn/ns-allinone-2.34/tcl8.4.18/unix:/home/unicorn/ns-allinone-2.34/tk8.4.18/unix

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/unicorn/ns-allinone-2.34/otcl-1.13:/home/unicorn/ns-allinone-2.34/lib:/home/unicorn/ns-allinone-2.34/tk8.4.18/unix:/home/unicorn/ns-allinone-2.34/tcl8.4.18/unix/

export TCL_LIBRARY=$TCL_LIBRARY:/home/unicorn/ns-allinone-2.34/tcl8.4.18/library

Enable Incompatible Add-Ons in Firefox

1. Open Firefox.
2. In the Address field, type about:config and hit Enter.
3. Click on the disclaimer “I’ll be careful, I promise” button.
4. Right-click and from the menu, select New and right after that Boolean.
5. A new, small window will appear on your screen.  Type in extensions.checkCompatibility.5.0 if you have Firefox 5.0. (Replace 5.0 by your version of Firefox).
6. Click OK.
7. When prompted select False and click OK.
8. Restart your browser for the changes to take effect.
9. Run and execute your old, incompatible  addons!