1. What is compression technique?
The techniques used for data compression is called compression technique. Compression technique is the process of encoding information using fewer bits through use of a specific encoding scheme.
2. Significance of compression techniques in multimedia system
There is much significance of compression techniques in multimedia system. With the techniques we get less disk space for data, faster reading and writing, faster file transfer, variable dynamic range and byte order independence.
3. Coding requirements in compression techniques
The basic coding requirements for compression techniques are storage, throughput and interaction.
Multimedia elements require much more space than text element, for example one second of uncompressed CD quality stereo audio is 176400 bytes and a true color full screen image requires 921600 bytes.
Continuous media requires a large amount of processing power that is throughput like uncompressed CD quality stereo audio stream needs 176400 bytes per second.
Multimedia system requires fast interaction between the sending and receiving ends, thus end to end delay should be small like video conference needs a delay less than 50 ms.
Kerberos Protocol.. A slide on it describing it with few words
Hi all,
I have prepared a short slide on kerberos protocol: what it is and how it works.
lets have a glimps on it..
KERBEROS_Slide
Kerberos slide [ mirror 2 ]
I have prepared a short slide on kerberos protocol: what it is and how it works.
lets have a glimps on it..
KERBEROS_Slide
Kerberos slide [ mirror 2 ]
Man In The Middle (MITM) Attack... In brief
What is a Man In The Middle Attack:
Man in the middle attack is a security attack in which the attacker intercepts and can be able to modify data that is transmitted between two users while the attacker pretends to be the other person to each user.
How this attack takes place:
In this type of attack the attacker intercepts messages in a public key exchange and then retransmits them substituting his own public key for the requested one so that the two original users still appear to be communicating with each other.
An example will make it clearer. Let, there are two parties Alice and Bob and the attacker is Trudy. Now this attack can be taken place in the following way.
Step 1: Alice says I am Alice. Trudy captures this message and passes it to Bob by pretending that this is from Alice.
Man in the middle attack is a security attack in which the attacker intercepts and can be able to modify data that is transmitted between two users while the attacker pretends to be the other person to each user.
How this attack takes place:
In this type of attack the attacker intercepts messages in a public key exchange and then retransmits them substituting his own public key for the requested one so that the two original users still appear to be communicating with each other.
An example will make it clearer. Let, there are two parties Alice and Bob and the attacker is Trudy. Now this attack can be taken place in the following way.
Step 1: Alice says I am Alice. Trudy captures this message and passes it to Bob by pretending that this is from Alice.
Developing j2me application on ubuntu [9.04]
First Install JDK:
To install jdk, open terminal and type those commands
sudo apt-get update
sudo apt-get install sun-java6-jdk
OR,
Application---> Add/Remove application
'Show:ALL available application
Search 'JAVA' Tick and apply
Downlaod Netbeans:
Now go to www.netbeans.org and downlaod the full version of the IDE.
After downloading install it....
Thats it your ide is ready for development.
Then create new project and select J2ME and choose option start developing.
A good emulator:
Download WTK for linux from java.sun.com
Install it..
for installing wtk see this guide.[Click Here]
Now U r ready to rock.....
To install jdk, open terminal and type those commands
sudo apt-get update
sudo apt-get install sun-java6-jdk
OR,
Application---> Add/Remove application
'Show:ALL available application
Search 'JAVA' Tick and apply
Downlaod Netbeans:
Now go to www.netbeans.org and downlaod the full version of the IDE.
After downloading install it....
Thats it your ide is ready for development.
Then create new project and select J2ME and choose option start developing.
A good emulator:
Download WTK for linux from java.sun.com
Install it..
for installing wtk see this guide.[Click Here]
Now U r ready to rock.....
Installing bind9 in ubuntu 9.10
Step 1:
On the terminal the following command was issued,
sudo apt-get install bind9
Step 2:
In this step we have configured the named.conf.local file. Before editing this file we have backed it up by issuing the command,
sudo cp /etc/bind/named.conf.local /etc/bind/named.conf.local.bkup
Then we have edited the file issuing the command
sudo gedit /etc/bind/named.conf.local
After editing the file was like this,
On the terminal the following command was issued,
sudo apt-get install bind9
Step 2:
In this step we have configured the named.conf.local file. Before editing this file we have backed it up by issuing the command,
sudo cp /etc/bind/named.conf.local /etc/bind/named.conf.local.bkup
Then we have edited the file issuing the command
sudo gedit /etc/bind/named.conf.local
After editing the file was like this,
Installing Samba in ubuntu 9.10
Step 1:
On the Terminal the following command was given one after another.
For LAN now we have to set up a manual IPV4 address and other related settings. In our case our IP address is 192.168.0.1 with 255.255.255.0 subnet mask.
For setting up the IP address we have followed the steps like,
From the system menu we have selected preferences then connection and then wired. Then there we have added the manual entry.
Step 3:
In this step we have configured the samba for our type of usages. We have used it for sharing files in a LAN.
Before editing the configuration file we have backed it up by issuing the following command
Step 4:
In this step we have restarted our samba server by issuing the following command
In this Step we we have accessed files from both windows and our linux machine.
For accessing file from windows machine, we just enter the ip address or browse file from the network places.
For accessing files from the linux machine to an windows machine,
At first we need to press ALT+F2 keys, then into the box we need to write smb://IP_address_of_windows_machine, like smb://192.168.0.101
On the Terminal the following command was given one after another.
sudo apt-get install sambaStep 2:
sudo apt-get install smbfs
For LAN now we have to set up a manual IPV4 address and other related settings. In our case our IP address is 192.168.0.1 with 255.255.255.0 subnet mask.
For setting up the IP address we have followed the steps like,
From the system menu we have selected preferences then connection and then wired. Then there we have added the manual entry.
Step 3:
In this step we have configured the samba for our type of usages. We have used it for sharing files in a LAN.
Before editing the configuration file we have backed it up by issuing the following command
sudo cp /etc/samba/smb.conf /etc/samba/smbk.confThen we have configured the smb.conf file. After the configuration the content of file looks like the following,
[global]Here the [Music] and [Home] are the shared folders on this particular pc.
workgroup=WORKGROUP
netbios name=test
server string= Samba Server
encrypt passwords=yes
security=share
map to guest = Bad user
[homes]
path=/home/saiful
read only=yes
browseable=yes
[Music]
path=/home/saiful/Music
read only=yes
browseable=yes
Step 4:
In this step we have restarted our samba server by issuing the following command
sudo /etc/init.d/samba restartStep 5:
In this Step we we have accessed files from both windows and our linux machine.
For accessing file from windows machine, we just enter the ip address or browse file from the network places.
For accessing files from the linux machine to an windows machine,
At first we need to press ALT+F2 keys, then into the box we need to write smb://IP_address_of_windows_machine, like smb://192.168.0.101
How to install Cisco packet tracer 5 in Ubuntu linux 9.04
U can install cisco packet tracer in ubuntu 9.04 now. For this all y have to do is to follow the following steps and u r done.
1. Download the packet tracer 5 from cisco site if u r student there [ The generic tar.gz format ] But if u r not a student then download it from here.
click this link to download
And keep the downloaded file in your home/ur_user_name directory.
click this link to download
And keep the downloaded file in your home/ur_user_name directory.
2. Open the terminal and write
"sudo
tar xzvf PacketTracer5_generic.tar.gz" [without the quotation mark]Give the sudo password.3. Now it is uncompressed. Go to your home directory and find the uncompressed folder. Enter into the folder and there u will find a file named "install".
double click on that file and a prompt will come up.
Select "Run in Terminal" option.Get back close maximize and minimize button on the right side in ubuntu 10.04 and 10.10
From ubuntu 10.04 metacity is besing used as GTK2 default window manager. On that the close maximize and minimize button is on the left side of the title bar which seems very hard to catch at the first time, we all feel hard then. So it is the best practice to make it as it was before on the right side . :D
now lets make it as it was with a few steps.
Step 1:
Press Alt and F2 button of ur keyboard at a time. A box will appear on that box just type
" gconf-editor " [except the "" ] and hit ur enter button or press Run button of that box.
Step 2:
# Then u will get another box. From that box at the left side select apps and expand it by clicking the downward arrow sign.
# Next expand the metacity and then select general
# Now look at right side and find button_layout and double click on it.
And on the value field just change it as I say ..
First put " : " this colon sign then minimize,maximize,close [with comma sign] or the order u want. and press enter button on ur keyboard.
You are done....
You got the buttons on the right side..
now lets make it as it was with a few steps.
Step 1:
Press Alt and F2 button of ur keyboard at a time. A box will appear on that box just type
" gconf-editor " [except the "" ] and hit ur enter button or press Run button of that box.
Step 2:
# Then u will get another box. From that box at the left side select apps and expand it by clicking the downward arrow sign.
# Next expand the metacity and then select general
# Now look at right side and find button_layout and double click on it.
And on the value field just change it as I say ..
First put " : " this colon sign then minimize,maximize,close [with comma sign] or the order u want. and press enter button on ur keyboard.
You are done....
You got the buttons on the right side..
Solution of problems After installing XAMPP In ubuntu distributions
After installing xampp the ubuntu users might face some problems, I will discuss the problem and the solution in this post.
At first have a look on how to install. [Click Here].
# The first problem may like error 404 not found....
For this u have to assured that u have started the lampp server by issuing this command
"sudo /opt/lampp/lampp start"
If u see that in the terminal it says that apache , mysql and proftpd has been started successfully, Then it is done, If not please let me the error it says in terminal by posting comments here.
After that u should open your browser and in the address bar just type localhost or 127.0.0.1
and press enter. In this moment u should see the apache or xampp's default page.
If u do not see things like this, just comment me the error it says.
# Next problem is like u are not able to create any directory or paste anything inside the "htdocs" folder.
For this at first u have to own the htdocs directory or folder. U can do this by issuing the following command
"sudo chown -R usergroup:username /opt/lampp/htdocs" [The path of htdocs folder]
Then u have to give all permissions to this htdocs folder by issuing the command
"sudo chmod 777 /opt/lampp/htdocs" [the path of htdocs folder]
now restart the lampp server and watch if ur problems are solved or not.
"sudo /opt/lampp/lampp restart"
this is the command for restarting the lampp server.
I hope this post will help u . For any problem make a comment here.
At first have a look on how to install. [Click Here].
# The first problem may like error 404 not found....
For this u have to assured that u have started the lampp server by issuing this command
"sudo /opt/lampp/lampp start"
If u see that in the terminal it says that apache , mysql and proftpd has been started successfully, Then it is done, If not please let me the error it says in terminal by posting comments here.
After that u should open your browser and in the address bar just type localhost or 127.0.0.1
and press enter. In this moment u should see the apache or xampp's default page.
If u do not see things like this, just comment me the error it says.
# Next problem is like u are not able to create any directory or paste anything inside the "htdocs" folder.
For this at first u have to own the htdocs directory or folder. U can do this by issuing the following command
"sudo chown -R usergroup:username /opt/lampp/htdocs" [The path of htdocs folder]
Then u have to give all permissions to this htdocs folder by issuing the command
"sudo chmod 777 /opt/lampp/htdocs" [the path of htdocs folder]
now restart the lampp server and watch if ur problems are solved or not.
"sudo /opt/lampp/lampp restart"
this is the command for restarting the lampp server.
I hope this post will help u . For any problem make a comment here.
Installing Samba in ubuntu 9.10
Step 1:
On the Terminal the following command was given one after another.
For LAN now we have to set up a manual IPV4 address and other related settings. In our case our IP address is 192.168.0.1 with 255.255.255.0 subnet mask.
For setting up the IP address we have followed the steps like,
From the system menu we have selected preferences then connection and then wired. Then there we have added the manual entry.
Step 3:
In this step we have configured the samba for our type of usages. We have used it for sharing files in a LAN.
Before editing the configuration file we have backed it up by issuing the following command
Step 4:
In this step we have restarted our samba server by issuing the following command
In this Step we we have accessed files from both windows and our linux machine.
For accessing file from windows machine, we just enter the ip address or browse file from the network places.
For accessing files from the linux machine to an windows machine,
At first we need to press ALT+F2 keys, then into the box we need to write smb://IP_address_of_windows_machine, like smb://192.168.0.101
On the Terminal the following command was given one after another.
sudo apt-get install sambaStep 2:
sudo apt-get install smbfs
For LAN now we have to set up a manual IPV4 address and other related settings. In our case our IP address is 192.168.0.1 with 255.255.255.0 subnet mask.
For setting up the IP address we have followed the steps like,
From the system menu we have selected preferences then connection and then wired. Then there we have added the manual entry.
Step 3:
In this step we have configured the samba for our type of usages. We have used it for sharing files in a LAN.
Before editing the configuration file we have backed it up by issuing the following command
sudo cp /etc/samba/smb.conf /etc/samba/smbk.confThen we have configured the smb.conf file. After the configuration the content of file looks like the following,
[global]Here the [Music] and [Home] are the shared folders on this particular pc.
workgroup=WORKGROUP
netbios name=test
server string= Samba Server
encrypt passwords=yes
security=share
map to guest = Bad user
[homes]
path=/home/saiful
read only=yes
browseable=yes
[Music]
path=/home/saiful/Music
read only=yes
browseable=yes
Step 4:
In this step we have restarted our samba server by issuing the following command
sudo /etc/init.d/samba restartStep 5:
In this Step we we have accessed files from both windows and our linux machine.
For accessing file from windows machine, we just enter the ip address or browse file from the network places.
For accessing files from the linux machine to an windows machine,
At first we need to press ALT+F2 keys, then into the box we need to write smb://IP_address_of_windows_machine, like smb://192.168.0.101
Installing Apache Tomcat server in ubuntu 9.04
To install Apache tomcat 6 server, we will follow some steps, they are described below:
Step1 : [ Adding sources ]
In this step we will add a third party source.
source Address:
deb http://us.archive.ubuntu.com/ubuntu/ jaunty multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ jaunty multiverse
just copy this and paste to ur sources.list file
To know how to add sources please visit this post.
step2 : [ Installing java jdk6 ]
To install this open the terminal and type or copy paste the following command.
" sudo apt-get install sun-java6-jdk "
Now jdk will be start installing please follow the on screen commands.
step3: [ Installing Tomcat server ]
" sudo apt-get install tomcat6 "
write the above command on the terminal and follow the on screen command.
step4 : [ Installing tomcat docs, examples and admin panel]
" sudo apt-get install tomcat6-docs tomcat6-examples tomcat6-admin "
write the following command on the terminal and follow the onscreen command.
==========================================
Your Installation is done.
now open any web browser and on its address bar type
" http://localhost:8080"
if you get a page containg IT WORKS message ur server is running Ok.
=============================================
Important Notes:
1. This server starts automatically every time when the system starts.
2. If you manually start or stop this server please follow the following commands and put them on the terminal.
" sudo /etc/init.d/tomcat6 start " [ To start the server ]
" sudo /etc/init.d/tomcat6 stop " [To stop the server ]
" sudo /etc/init.d/tomcat6 restart " [ To restart the server ]
3. All files regarding this server installation are located at this Location:
" /usr/share/tomcat6 " directory.
4. Webapps folder located at " /var/lib/tomcat6/webapps " location.
Step1 : [ Adding sources ]
In this step we will add a third party source.
source Address:
deb http://us.archive.ubuntu.com/ubuntu/ jaunty multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ jaunty multiverse
just copy this and paste to ur sources.list file
To know how to add sources please visit this post.
step2 : [ Installing java jdk6 ]
To install this open the terminal and type or copy paste the following command.
" sudo apt-get install sun-java6-jdk "
Now jdk will be start installing please follow the on screen commands.
step3: [ Installing Tomcat server ]
" sudo apt-get install tomcat6 "
write the above command on the terminal and follow the on screen command.
step4 : [ Installing tomcat docs, examples and admin panel]
" sudo apt-get install tomcat6-docs tomcat6-examples tomcat6-admin "
write the following command on the terminal and follow the onscreen command.
==========================================
Your Installation is done.
now open any web browser and on its address bar type
" http://localhost:8080"
if you get a page containg IT WORKS message ur server is running Ok.
=============================================
Important Notes:
1. This server starts automatically every time when the system starts.
2. If you manually start or stop this server please follow the following commands and put them on the terminal.
" sudo /etc/init.d/tomcat6 start " [ To start the server ]
" sudo /etc/init.d/tomcat6 stop " [To stop the server ]
" sudo /etc/init.d/tomcat6 restart " [ To restart the server ]
3. All files regarding this server installation are located at this Location:
" /usr/share/tomcat6 " directory.
4. Webapps folder located at " /var/lib/tomcat6/webapps " location.
Adding package repository sources to source list in ubuntu
To add sources to source list we can follow either Terminal mode Or from the GUI mode we can add sources to source.list file.
I will describe both the ways....
From Terminal:
# At first open the terminal [ Application>>Accessories>>Terminal ]
# Then write the following command on the terminal [Except the "" marks]
" sudo gedit /etc/apt/sources.list "
# If required provide the sudo password or your user password.
# Then a new window will open.
# In that window at last of that window just add your sourcess and save the file and close. You are done.
# Now write " sudo apt-get update " in the terminal.
Now it is updated.
From GUI Mode:
To add sources from GUI mode,
#Click on System>>Administration>>Software sources.
#If required give ur sudo password.
#A new window will come , in that window select Third party software tab and at the bottom left corner u will get an ADD button. Click on that, A text box will appear and paste your source there and press ok.
#Now close the window and u will be prompted to update ur aptitude list. click ok there. You are done.
I will describe both the ways....
From Terminal:
# At first open the terminal [ Application>>Accessories>>Terminal ]
# Then write the following command on the terminal [Except the "" marks]
" sudo gedit /etc/apt/sources.list "
# If required provide the sudo password or your user password.
# Then a new window will open.
# In that window at last of that window just add your sourcess and save the file and close. You are done.
# Now write " sudo apt-get update " in the terminal.
Now it is updated.
From GUI Mode:
To add sources from GUI mode,
#Click on System>>Administration>>Software sources.
#If required give ur sudo password.
#A new window will come , in that window select Third party software tab and at the bottom left corner u will get an ADD button. Click on that, A text box will appear and paste your source there and press ok.
#Now close the window and u will be prompted to update ur aptitude list. click ok there. You are done.
Installing TP-link WN620G wireless adapter in ubuntu 9.04
To install this device in ubuntu 9.04 U have to follow the following steps....
1:
First Install the ndiswrapper driver. To know how to install see this.
2:
Now download the windows driver from Here.
3:
Now unzip the folder and from the terminal locate the drivers location.
For example in this package the files are located like this
Desktop/2007116174835/Win2000_XP/DriverFiles/
4:
Now write the following commands in terminal: (except "" marks)
>>" sudo ndiswrapper -i net5523.inf "
Now check if it is installed or not : ( You may now insert the device in usb port)
write this in terminal " sudo ndiswrapper -l "
Now start the device by writing " sudo modprobe ndiswrapper " in terminal.
Now u will see ur device led blinking. Now u can set ur wireless network.
ON my next post I will describe how to setup or connect to a wireless network.
=================================
For the details documentation u may follow the link below:
https://help.ubuntu.com/community/WifiDocs/Device/TP-Link_TL-WN620G_(ndiswrapper)
1:
First Install the ndiswrapper driver. To know how to install see this.
2:
Now download the windows driver from Here.
3:
Now unzip the folder and from the terminal locate the drivers location.
For example in this package the files are located like this
Desktop/2007116174835/Win2000_XP/DriverFiles/
4:
Now write the following commands in terminal: (except "" marks)
>>" sudo ndiswrapper -i net5523.inf "
Now check if it is installed or not : ( You may now insert the device in usb port)
write this in terminal " sudo ndiswrapper -l "
Now start the device by writing " sudo modprobe ndiswrapper " in terminal.
Now u will see ur device led blinking. Now u can set ur wireless network.
ON my next post I will describe how to setup or connect to a wireless network.
=================================
For the details documentation u may follow the link below:
https://help.ubuntu.com/community/WifiDocs/Device/TP-Link_TL-WN620G_(ndiswrapper)
Installing NDiswrapper in ubuntu 9.04
Ndiswrapper is the driver utility for wirless devices like builtin or external wireless adapter. By default in ubuntu 9.04 it is not installed. If ur wireless device do not work properly in ubuntu 9.04 u may need to install this drivers.
Lets see how it can be installed in Ubuntu 9.04.
There are many processes to install it. I will describe some of them.
Process 1:
If you have an available internet connection then just open the terminal and type there
" sudo apt-get install ndisgtk " [except the "" marks"]
and press enter key after that u r prompted to give ur sudo password just give it and hit enter.
The process will start installing the drivers...
You are done.
Process 2:
You can also install this from the GUI mode
Fisrt go to system >>Administartion>>synaptic package manager
Then type ndis in the search box positioned in upper right corner of that window.
just mark the ndisgtk package and click apply button.
You are done.
============================
For further reading u can follow the link below:
https://help.ubuntu.com/community/WifiDocs/Driver/Ndiswrapper
Lets see how it can be installed in Ubuntu 9.04.
There are many processes to install it. I will describe some of them.
Process 1:
If you have an available internet connection then just open the terminal and type there
" sudo apt-get install ndisgtk " [except the "" marks"]
and press enter key after that u r prompted to give ur sudo password just give it and hit enter.
The process will start installing the drivers...
You are done.
Process 2:
You can also install this from the GUI mode
Fisrt go to system >>Administartion>>synaptic package manager
Then type ndis in the search box positioned in upper right corner of that window.
just mark the ndisgtk package and click apply button.
You are done.
============================
For further reading u can follow the link below:
https://help.ubuntu.com/community/WifiDocs/Driver/Ndiswrapper
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