How to rar/unrar the files on Linux operating system using open command terminal

Using rarlinux
download rarlinux tool from win-rar website and Gunzip the downloaded rarlinux-3.7.1.tar.gzip file
[root@vinsun]#gunzip rarlinux-3.7.1.tar.gzip
To extract the gunzipped but .tar file
[root@vinsun]#tar xvf rarlinux-3.7.1.tar
The above will extract the tar file to a folder in your present working directory called rar.
enter tho the rar dir
[root@vinsun]# cd ./rar
long list the rar folder -
[root@vinsun]# ls -l ./rar
You should see an executable file called unrar. There you go -
To unrar a file -
[root@vinsun]# ./unrar x file.rar
To extract a password protected rar file -
[root@vinsun]#./unrar x -p[password] file.rar


Using unrar:
Fetch and install unrar tools from fedora extra repository -
[root@cafe moon]#yum install unrar
To see unrar help pages-
[root@cafe moon]# unrar ?
To extract a rar file -
[root@cafe moon]# unrar x file.rar
To extract a password protected rar file -
[root@cafe moon]#unrar x -p[password] file.rar

Using rarlinux:
Download the rarlinux tool from Winrar website and Gunzip the downloaded rarlinux-3.7.1.tar.gzip file
[root@cafe moon]#gunzip rarlinux-3.7.1.tar.gzip
To extract the gunzipped but .tar file
[root@cafe moon]#tar xvf rarlinux-3.7.1.tar
The above will extract the tar file to a folder in your present working directory called rar.
enter tho the rar dir
[root@cafe moon]# cd ./rar
long list the rar folder -
[root@cafe moon]# ls -l ./rar
You should see an executable file called unrar. There you go -
To unrar a file -
[root@cafe moon]# ./unrar x file.rar
To extract a password protected rar file -
[root@cafe moon]#./unrar x -p[password] file.rar

Interview question for Wipro and other network career MNC company

Computer Networks

1. What are the two types of transmission technology available?

  (i) Broadcast    and (ii) point-to-point



2. What is subnet?

  A generic term for section of a large networks usually separated by a bridge or router.



3. Difference between the communication and transmission.

  Transmission is a physical movement of information and concern issues like bit polarity, synchronisation, clock etc.

  Communication means the meaning full exchange of information between two communication media.



4. What are the possible ways of data exchange?

  (i) Simplex   (ii) Half-duplex (iii) Full-duplex.



5. What is SAP?

  Series of interface points that allow other computers to communicate with the other layers of network protocol stack.



6. What do you meant by "triple X" in Networks? 

The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between hte PAD and the network, called X.29. Together, these three recommendations are often called "triple X"



7. What is frame relay, in which layer it comes?

Frame relay is a packet switching technology. It will operate in the data link layer.



8. What is terminal emulation, in which layer it comes?

  Telnet is also called as terminal emulation. It belongs to application layer.



9. What is Beaconing?

  The process that allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used in Token ring and FDDI networks.



10.  What is redirector?

  Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.



11.  What is NETBIOS and NETBEUI?

  NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications.

  NETBEUI is NetBIOS extended user interface. A transport protocol designed by microsoft and IBM for the use on small subnets.



12.  What is RAID?

  A method for providing fault tolerance by using multiple hard disk drives.



13.  What is passive topology?

  When the computers on the network simply listen and receive the signal, they are referred to as passive because they don’t amplify the signal in any way. Example for passive topology - linear bus.



14.  What is Brouter?

  Hybrid devices that combine the features of both bridges and routers.



15.  What is cladding?

  A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable.



16.  What is point-to-point protocol

  A communications protocol used to connect computers to remote networking services including Internet service providers.



17.  How Gateway is different from Routers?

  A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures or data formats



18.  What is attenuation?

  The degeneration of a signal over distance on a network cable is called attenuation.



19.  What is MAC address?

  The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.



20.  Difference between bit rate and baud rate.

  Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits.

baud rate  = bit rate / N

where N is no-of-bits represented by each signal shift.



21.  What is Bandwidth?

Every line has an upper limit and a lower limit  on the frequency of signals it can carry. This limited range is called the bandwidth.



22.  What are the types of Transmission media?

Signals are usually transmitted over some transmission media that are broadly classified in to two categories.

a) Guided Media:

These are those that provide a conduit from one device to another that include twisted-pair, coaxial cable and fiber-optic cable. A signal traveling along any of these media is directed and is contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic that accept and transport signals in the form of electrical current. Optical fiber is a glass or plastic cable that accepts and transports signals in the form of light.

b) Unguided Media:

This is the wireless media that transport electromagnetic waves without using a physical conductor. Signals are broadcast either through air. This is done through radio communication, satellite communication and cellular telephony.



23.  What is Project 802?

It is a project started by IEEE to set standards to enable intercommunication between equipment from a variety of manufacturers. It is a way for specifying functions of the physical layer, the data link layer and to some extent the network layer to allow for interconnectivity of major LAN

protocols.

It consists of the following:

Ø 802.1 is an internetworking standard for compatibility of different LANs and MANs across protocols.

Ø 802.2 Logical link control (LLC) is the upper sublayer of the data link layer which is non-architecture-specific, that is remains the same for all IEEE-defined LANs.

Ø Media access control (MAC) is the lower sublayer of the data link layer that contains some distinct modules each carrying proprietary information specific to the LAN product being used. The modules are Ethernet LAN (802.3), Token ring LAN (802.4), Token bus LAN (802.5).

Ø 802.6 is distributed queue dual bus (DQDB) designed to be used in MANs.



24.  What is Protocol Data Unit?

The data unit in the LLC level is called the protocol data unit (PDU). The PDU contains of four fields a destination service access point (DSAP), a source service access point (SSAP), a control field and an information field. DSAP, SSAP are addresses used by the LLC to identify the protocol stacks on the receiving and sending machines that are generating and using the data. The control field specifies whether the PDU frame is a information frame (I - frame) or a supervisory frame (S - frame) or a unnumbered frame (U - frame).



25.  What are the different type of networking / internetworking devices?

Repeater:

Also called a regenerator, it is an electronic device that operates only at physical layer. It receives the signal in the network before it becomes weak, regenerates the original bit pattern and puts the refreshed copy back in to the link.

Bridges:

These operate both in the physical and data link layers of LANs of same type. They divide a larger network in to smaller segments. They contain logic that allow them to keep the traffic for each segment separate and thus are repeaters that relay a frame only the side of the segment containing the intended recipent and control congestion.

Routers:

They relay packets among multiple interconnected networks (i.e. LANs of different type). They operate in the physical, data link and network layers. They contain software that enable them to determine which of the several possible paths is the best for a particular transmission.

Gateways:

They relay packets among networks that have different protocols (e.g. between a LAN and a WAN). They accept a packet formatted for one protocol and convert it to a packet formatted for another protocol before forwarding it. They operate in all seven layers of the OSI model.



26.  What is ICMP?

ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.



27.  What are the data units at different layers of the TCP / IP protocol suite?

The data unit created at the application layer is called a message, at the transport layer the data unit created is called either a segment or an user datagram, at the network layer the data unit created is called the datagram, at the data link layer the datagram is encapsulated in to a frame and finally transmitted as signals along the transmission media.



28.  What is difference between ARP and RARP?

The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP query packet that includes the IP address of the receiver.

The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.



29.  What is the minimum and maximum length of the header in the TCP segment and IP datagram?

The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes. 

30.  What is the range of addresses in the classes of internet addresses?

Class A  0.0.0.0   - 127.255.255.255

Class B  128.0.0.0    - 191.255.255.255

Class C  192.0.0.0    - 223.255.255.255

Class D  224.0.0.0    - 239.255.255.255

Class E 240.0.0.0    - 247.255.255.255  



31.  What is the difference between TFTP and FTP application layer protocols?

The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.

The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file from one host to another. It uses the services offer by TCP and so is reliable and secure. It establishes two connections (virtual circuits) between the hosts, one for data transfer and another for control information.



32.  What are major types of networks and explain?

Ø Server-based network

Ø Peer-to-peer network

Peer-to-peer network, computers can act as both servers sharing resources and as clients using the resources.

Server-based networks provide centralized control of network resources and rely on server computers to provide security and network administration



33.  What are the important topologies for networks?

Ø BUS topology:

In this each computer is directly connected to primary network cable in a single line.

Advantages:

Inexpensive, easy to install, simple to understand, easy to extend.



Ø STAR topology:

In this all computers are connected using a central hub.

Advantages:

Can be inexpensive, easy to install and reconfigure and easy to trouble shoot physical problems.



Ø RING topology:

In this all computers are connected in loop.

Advantages:

All computers have equal access to network media, installation can be simple, and signal does not degrade as much as in other topologies because each computer regenerates it.



34.  What is mesh network?

A network in which there are multiple network links between computers to provide multiple paths for data to travel.



35.  What is difference between baseband and broadband transmission?

In a baseband transmission, the entire bandwidth of the cable is consumed by a single signal. In broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.



36.  Explain 5-4-3 rule?

In a Ethernet network, between any two points on the network ,there can be no more than five network segments or four repeaters, and of those five segments only three of segments can be populated.



37.  What MAU?

In token Ring , hub is called Multistation Access Unit(MAU).



38.  What is the difference between routable and non- routable protocols?

Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router



39.  Why should you care about the OSI Reference Model?

It provides a framework for discussing network operations and design.



40.  What is logical link control?

One of two sublayers of the data link layer of OSI reference model, as defined by the IEEE 802 standard. This sublayer is responsible for maintaining the link between computers when they are sending data across the physical network connection.



41.  What is virtual channel?

Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.



42.  What is virtual path?

Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path.



43.  What is packet filter?

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.



44.  What is traffic shaping?

One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.



45.  What is multicast routing?

Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing.



46.  What is region?

When hierarchical routing is used, the routers are divided into what we will call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.



47.  What is silly window syndrome?

It is a problem that can ruin TCP performance. This problem occurs when data are passed to the sending TCP entity in large blocks, but an interactive application on the receiving side reads 1 byte at a time.



48.  What are Digrams and Trigrams?

The most common two letter combinations are called as digrams. e.g. th, in, er, re and an. The most common three letter combinations are called as trigrams. e.g. the, ing, and, and ion.



49.  Expand IDEA.

IDEA stands for International Data Encryption Algorithm.



50.  What is wide-mouth frog?

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.



51.  What is Mail Gateway?

It is a system that performs a protocol translation between different electronic mail delivery protocols.



52.  What is IGP (Interior Gateway Protocol)?

It is any routing protocol used within an autonomous system.



53.  What is EGP (Exterior Gateway Protocol)?

It is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.



54.  What is autonomous system?

It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol.



55.  What is BGP (Border Gateway Protocol)?

It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. This is newer than EGP (Exterior Gateway Protocol).



56.  What is Gateway-to-Gateway protocol?

It is a protocol formerly used to exchange routing information between Internet core routers.



57.  What is NVT (Network Virtual Terminal)?

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.



58.  What is a Multi-homed Host?

It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multi-homed Host.



59.  What is Kerberos?

It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.



60.  What is OSPF?

It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet's topology to make accurate routing decisions.



61.  What is Proxy ARP?

It is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.



62.  What is SLIP (Serial Line Interface Protocol)?

It is a very simple protocol used for transmission of IP datagrams across a serial line.



63.  What is RIP (Routing Information Protocol)?

It is a simple protocol used to exchange information between the routers.



64.  What is source route?

It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.

How to install Ns-2 doc linux/windows

-->

NS2 Installation Procedure (For Root User)

• Check for the complete LINUX installation (with all the options enabled during installation) in the system.
• During installation of NS2 its better to get into the ROOT login.
• Copy the given ns-allinone-2.34.tar.gz file in the root directory.
• Extract the files in the same folder using extract option or the command in the terminal as

root>tar -zxvf ns-allinone-2.34.tar.gz

• The files will be extracted in the newly created folder as ns-allinone-2.34.
• Now go to the terminal and get into the folder ns-allinone-2.34 and do the following

Root> cd ns-allinone-2.34

Root/ns-allinone-2.34 >./install

• This command will run for 10-15 minutes. If it is a successful installation you will be getting IMPORTANT NOTICE notes (detailing about the paths to set)
• Copy the ns-21 file given into the following folder

Computer/file system/etc/profile.d

• Now close all the terminal and open a new terminal and get into the folder root/ns-allinone-2.34 and give ns command and you will be getting as below when you each time press ENTER key which indicates that the installation is complete .
  • Root/ns-allinone-2.34>./validate

Root/ns-allinone-2.34>ns

%

%

%exit

• Now you can run the programs in a new terminal.

What ns-21 consists of??

It consist of path

PATH=$PATH:$HOME/bin:/root/ns-allinone-2.34/bin:/root/ns-allinone-2.34/tcl8.4.18/unix:/root/ns-allinone-2.34/tk8.4.18/unix

export LD_LIBRARY_PATH=/root/ns-allinone-2.34/otcl-1.13:/root/ns-allinone-2.34/lib

export TCL_LIBRARY=/root/ns-allinone-2.34/tcl8.4.18/library

NS2 Installation Procedure (For other User)

Open terminal window

Type $ su & give root password & follow the above mention procedure

For copying ns21.sh file use following command

cp<space><source path><space> <destination path(/etc/profile.d)>

How to create(Enable) a Root User

• Step1

$ su (give password)

Now it becomes Root

cd <space>/etc/pam.d

Vim gdm

Remove # symbol from 3^rd line

Vim gdm- password

Remove! Symbol from 3^rd line end

How to install Ns-2 in Windows

 

Windows shortcuts using keyboard

Winlogokey Display or hide the Start menu.

Winlogokey + BREAK Display the System Properties dialog box.

Winlogokey + D Show the desktop.

Winlogokey + M Minimize all windows.

Winlogokey + Shift + M Restores minimized windows.

Winlogokey + E Open My Computer [Explorer Mode].

Winlogokey + F Search for a file or folder.

Winlogokey + CTRL + F Search for computers.

Winlogokey + F1 Display Windows Help.

Winlogokey + R Open the Run dialog box.

Winlogokey + U Open Utility Manager.

Winlogokey + L Lock your computer if you are connected to a network domain, or switch users if you are not connected to a network domain.

Winlogokey + U + U Shutdown Your Computer
Winlogokey + U + R Restart Your Computer


F1 Help

F2 Rename Selected File

F3 Open Search

F4 Display the Address bar list in My Computer or Windows Explorer.

F5 Refresh

F6 Cycle through screen elements in a window or on the desktop.

F10 Activate the menu bar in the active program.

F11 Fullscreen Window [Internet Explorer only]

SHIFT + F10 Right Click of MOUSE

HP laptop Windows 7 recovery discs fails for new hard drive

This process clears all information from the hard drive to prepare the hard drive for system recovery.

1. Enter the system BIOS and select the Boot menu.

2. Change the startup (boot) order so the computer starts from the first optical drive (CD-ROM/ATAPI CD-ROM/DVD). You may need to enter a sub-menu called Boot Device Priority .

3. Insert Disk 1 of the System Recovery disk set in the first (top) optical drive.

4. Press F10 , then press Enter to save the changes and restart the computer.

   When the PC restarts, it reads from the Recovery CD, and displays a screen of options (typically R , F , and Q ).

5. Press and hold the Ctrl key, and press the Backspace key. The Manufacturer Menu is displayed.

   
   Manufacturer Menu:

   <1> boot from drive 1

   <2> Start recovery program on CD/DVD

   <3> boot Floppy a:

   <4> clear the partition table of drive 1

   <5> erase the Master Boot Record of drive 1

   <6> wipe all sectors of drive 1

   <7> create a primary partition on drive 1

   <8> create a SmartImage partition on drive 1

   <9> Install ST Master Boot Record

   <A> Install Standard Master Boot Record

   <S> Save DMI Sysinfo to drive 1

   <T> Test the system RAM for defects

   <ESC> restart this CDROM

NOTE: Drive 1 may be shown as 0x80 in the menu of earlier versions.Not all options shown in the list below will be available for some PCs.

Select option clear the partition table .

The following message appears: No Operating System Installed or Partition CorruptedPress "R" to perform a full system recovery .

Do not press R . Instead, press and hold ctrl , then press Backspace to bring up the Tools Menu.

Select option erase the Master Boot Record of drive .

The following message appears: No Operating System Installed or Partition CorruptedPress "R" to perform a full system recovery .

Do not press R . Instead press and hold down ctrl , then press Backspace to bring up the Tools Menu.

NOTE: If there are no partitions, the following message appears: No MBR or master boot record found .Continue using these steps.

Select option wipe all sectors of drive .

An Erasing Hard Drive progress bar will appear. This process will take approximately from 15 minutes to over one hour, depending on the size of the hard drive.

When the hard drive is completely erased, the following message is displayed:

No Operating System Installed or Partition CorruptedPress "R" to perform a full system recovery

Press R to begin the automatic System Recovery process.

NOTE: This procedure requires that you have a set of System Recovery CDs or DVDs for the computer. Also, the Manufacturer Menu is only available on Summer 2002 and newer models. The Manufacturer Menu is not available for System Recovery performed from the hidden partition.

CAUTION: If an additional hard drive has been installed, disconnect the power and IDE cables from the additional drive. This is necessary to prevent data loss on the added hard drive.

How To Install ns3 on linux in ubuntu, fedora, linux?

we will see how to install ns3 on linux box. The home page of ns3 is NS3 Home
the current release is ns3.10 (January 5, 2011) and can be downloaded from DOWNLOAD NS3.10

Step 1: Download ns3.10 and save it some where , but on the same machine where you want to install (Just Kidding )
Step 2: open the terminal and go to the folder where ns3.10 tar file is.
Step 3: from the terminal run :

$tar -xvf ns-allinone-3.10.tar.bz2
$cd ns-allinone-3.10
$./build.py

you can provide some options to build.py but as a newbie use the default one
When the build process get over (it will take some time), type

$cd ns-3.10

and now we will validate our installation

$./test.py

the out put of this will be some thing like this:

Waf: Entering directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’
Waf: Leaving directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’
‘build’ finished successfully (2.010s)
PASS: TestSuite lte-bearer
PASS: TestSuite lte-propagation-loss-model
PASS: TestSuite wimax-fragmentation
PASS: TestSuite lte-phy

…………..

PASS: Example examples/tcp/tcp-nsc-lfn

PASS: Example examples/wireless/wifi-ap.py

PASS: Example src/contrib/flow-monitor/examples/wifi-olsr-flowmon.py

168 of 168 tests passed (168 passed, 0 skipped, 0 failed, 0 crashed, 0 valgrind errors)

Step 4:  Now our ns3 is installed and ready to run sample programs.

right now we are in directory “ns-3.10″

from terminal :

$ cp examples/tutorial/first.cc scratch/myfirst.cc

$./waf

this time waf will give some thing like this:

Waf: Entering directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’

Waf: Leaving directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’

‘build’ finished successfully (15.900s)

Step 5: now it is the time to run the simulation

$ ./waf –run myfirst

Waf: Entering directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’

Waf: Leaving directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’

‘build’ finished successfully (1.353s)

Sent 1024 bytes to 10.1.1.2

Received 1024 bytes from 10.1.1.1

Received 1024 bytes from 10.1.1.2

Congratulations !! NS3 is installed and running successfully.

Lets try some other example.

Again go to the terminal and type

$cp examples/wireless/ofdm-validation.cc scratch/myofdm.cc

$./waf

out put will be:

Waf: Entering directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’

[1330/1502] cxx: scratch/myofdm.cc -> build/debug/scratch/myofdm_2.o

[1500/1502] cxx_link: build/debug/scratch/myofdm_2.o -> build/debug/scratch/myofdm

Waf: Leaving directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’

‘build’ finished successfully (5.842s)

now run the simulation:

$ ./waf –run myofdm

this time output will be:

Waf: Entering directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’

Waf: Leaving directory `/media/Installations/ns-allinone-3.10/ns-3.10/build’

‘build’ finished successfully (1.448s)

OfdmRate6Mbps

OfdmRate9Mbps

OfdmRate12Mbps

OfdmRate18Mbps

OfdmRate24Mbps

OfdmRate36Mbps

OfdmRate48Mbps

OfdmRate54Mbps

So, this way you can try different examples, and get an introduction of ns3.

Note: As I am using Fedora 14 Complete Installation, I have not feel the need to resolve the dependencies, but if you will come across any error then please make me know, so that I will extend the post to cover the dependencies problems, and to other distributions also like ubuntu etc.

Enjoy Ns3 , soon, I will come back with tutorials on ns3 and dependencies resolution for ns3 (only if some will mention the errors

how to patch nam, tk, gt-itm, libgb.a, eval.c in ns2 (install steps ns2.28)

1) Decompress ns-allinone 2.28
tar xvzf  ns-allinone-2.28.tar.gz

2) Patch nam: you need the patch file (I attach it)
cp nam-1.11.patch ns-allinone-2.28/nam-1.11/
cd ns-allinone-2.28/nam-1.11/
patch -p0 < ./nam-1.11.patch

3) Patch tk: you need the pacth file (I attach it)
cp tk-8.4-lastevent.patch ns-allinone-2.28/tk8.4.5/
cd ns-allinone-2.28/tk8.4.5/patch -p0 < ./tk-8.4-lastevent.patch 

4) Modify gt-itm files:
4.1) Create the following directories:
mkdir ns-allinone-2.28/gt-itm/bin
mkdir ns-allinone-2.28/gt-itm/lib
4.2) Copy the libgb.a file (I attach it) into the lib folder
cp libgb.a ns-allinone-2.28/gt-itm/lib
4.3) Copy the eval.c file (I attach it) into the src folder
cp eval.c ns-allinone-2.28/gt-itm/src

5) Install ns
cd ns-allinone-2.28/
./install

How to intall ns2 in windows using cywin (Windows + Cygwin + NS2)

--> This document will show you how to install my NS2 (ns-2.28 + all my modules) on Windows platform (windows 2000 or windows XP). 

If you follow each step in this webpage, you can successfully run all the simulation scripts provided me without installing each module. 

(It includes TKN 802.11e EDCF module, NOAH routing, MFlood, CSFQ, Poisson traffic, wireless random uniform and GE error model, and tcldebug.)2006/10/27 add “Evalvid-RA” and wimax “IEEE 802.16 module for ns2 (from NIST)”.

[Cygwin]
1.      Download the cygwin.rar.

2.      Decompress the cygwin.rar

1.      Click the setup.exe to install cygwin.

2.      Because the language of operating system is Traditional Chinese. The text of button is shown in Chinese. But you don’t need to worry about this. I think it is shown in English in your computer. Just click “Next”.

3.      Then choose “Install from Local Directory”

4.      Click “Next”.

(Just keep the settings as they are.) 
 
5.      Click “Next”

6. Click “Browse” to choose where the software is. (Please choose “ftp%3a%2f%2fftp.nctu.edu.tw%2fWindows%2fcygwin”)

7.      Click “OK”.

8.      Click “Next” and you will see the figure shown as follows. In this window, the cygwin setup program let you choose what software you want to install.

9.      Click “View” first to make the word “Category “change to “Full”.

10.  XFree86-base, XFree86-bin, XFree86-prog, XFree86-lib, XFree86-etc, make, patch, perl, gcc, gcc-g++, gawk, gnuplot, tar and gzip must be chosen. For example, if I want to install XFree-86 base (upper figure), click the “Skip” of “New” column. The “Skip” will be changed to “4.3.0-1” (lower figure).

11.  Click “Next”.

(Please be patient. It may take a long time to finish the installation.)

12.  When setup is done, it will be shown as following figure. Click “Finish”.

13.  Click “OK” to finish the cygwin setup program.
[myNS2 setup]

1.      Click the icon on the desktop.

2.      For the first time execution, it will generate some environment parameter setting files. In this example, smallko is my login name to windows system. Therefore, the cygwin will create a folder named “smallko” under home directory. (The actual path for smallko folder is: c:\cygwin\home\smallko) It should be noticed that the login name can not have any space in your name. For example, “A B” may cause errors when you install NS2.

3.      Download myNS2.

4.      Decompress the ns-allinone-2.28.rar.

5.      Move this folder under c:\cygwin\home\smallko. (change smallko (login name) with yours)

6.      Open a cygwin window

7.      Change the path to ns-allinone-2.28/ns-2.28

8.      Run the command “./configure; make clean; make

9.      Please be patient. It will take some time to finish the compilation.

10.  When it is done, it should look like as follows.

11.  To make sure that you have successfully installed myNS2, you need to check whether you can find ns.exe under ns-allinone-2.28/ns-2.28

12.  Copy the .bashrc to c:/cygwin/home/smallko 
 
13.  Run the example script to test whether you have setup the path or not.

14.  If you see the error message like “ns command not found”, no worry about this. Sometimes even you have setup the path, but it does not work. You can copy the ns.exe (nam.exe) to the same place as the simulation script. Run the simulation with “./ns.exe” and it will be ok.

How to Merge Hotmail with Gmail acoounts into single mail inbox

how to do it:

1. Go to the Accounts tab from Gmail’s settings page and click on “Add a mail account you own”.
2. Follow these settings:
3. That’s it! All done. You also have the option to add the Hotmail address as a custom “From” address so you no longer have to compose messages in Hotmail.

Start or booting Windows xp, 7, vista in Safe Mode, safe mode with Networking, safe mode with command prompt

Steps to Start Windows in Safe Mode with Networking

• Reboot your computer.
• Press F8 key until you see the Windows XP Advance Option menu.
• Select “Safe Mode with Networking”.

Some Important Steps To Remove Virus Manually From Windows7

Here I am going to discuss how to remove virus manually from your computer . Some time your computer behave just like old two-wheeler which has a defected engine, takes more time  to start, can’t take loads. The same symptoms are seen in your computer. For your computer, the possible reason to slow down it is Virus like trojan, newfolder.exe, ravmon.exe, smss.exe  etc (read also re-enable windows taskmgr disabled by administrator). Some time the Antivirus Live viruses also infect your computer.
Then what you will do if You have no Internet connection available in your PC then you can’t update regularly your anti virus?You can still throw out your headache and remove the virus manually.

How will you determine if your computer is virus infected or not?

The general symptom of virus infections are

1. Your Task Manager is disabled.When you want to open it then the message  “Task Manager has been disabled by your administrator” appears.
2. Disabled Registry Editor:If you are trying to run “regedit” command the message “Registry editing has been disabled by your administrator” appears.
3. Disabled Command Prompt:“The command prompt has been disabled by your administrator. Press any key to continue”.
4. Some time the CPU usage jumps to 50% even though you have no application open.
5. The drives in my computer does not open by double click.
6. Automatic Shut down.
7. Computer becomes slower.
8. The hidden files can not be showing .as the Folder Option will be disappear.

Solution to remove the viruses manually

To remove the viruses manually, you have to recognize them first.

1. You can view the suspicious processes active and their CPU usage in Task manager and can identify the virus for which it is occurring. But your Task manager is disabled. So you can use Process Explorer as a task manager alternative. It is portable and free version,You can store it in you USB Flash Drive. Download Process Explorer.
2. It is not possible to make changes at all without registry editing. But it is disabled for you.You can use lternative Registry Editor “Regalyzer” Developed by the famous author of SpyBot. Download RegAlyzer
3. To enable the Run command you can use Run dialog replacement v1.0. It is useful for run important command. If you have Process Explorer the it will be needed. Download Run dialog replacement v1.0.
4. If my computer is virus infected then I will first go to check MSCONFIG.In MSCONFIG you can view all the program that start at the boot up of your system.The virus developer are much aware of it and so they delete the MSCONFIG.exe files from your system or change the reference of it.If you type MSCONFIG in ‘”Run” you should get the message “Windows cannot find ‘msconfig’.Autoruns is a suitable alternative of MSCONFIG. Download Autoruns.
5. 5.Most virus are .exe hidden files and you can not see them because the folder option where you may change the file view option,is disabled.The best free file manager in vision is FreeCommander.It is a powerful tool which shows all the hidden files. Download FreeCommander

N.B: You can download the PowerExesPack to get the tools together.
Download:  PowerExesPack

Process Terminating

Install Process explorer.Run it from Start Menu.
Now follow the instruction.

After collapsing:

procexp.exe is a Explorer’s own process.
if you view a process like winlogon.exe in explorer tree then it is surely a virus.
If any suspicious process are seen then Right click on it and then properties.From the field “Path “ copy the path and open Run Dialogue box and paste there.Now terminate the suspicious process  from Process Explorer.

How to delete the suspicious files

To delete the suspicious files go to Start Menu->7-ZIP->7-ZIP FILE MANAGER .
It will show all the hidden files and go to the root path of every drive.

File Deletion

The second step is deleting files. If you have installed powerexe, Start Menu–> 7-ZIP–> 7-ZIP File Manager which will show you all hidden files and go through the root path of every drive.
Delete the .exe files and autorun.inf like ravmon.exe,smss.exe,newfloder.exe
But don’t delete the following files:
autoexec.bat, boot.ini, bootmgr,config.sys, io.sys, msdos.sys, ntdetect.com, pagefile.sys,ntldr, hiberfil.sys

Remove the start up entries

Open Autoruns by typing autoruns in the Run Dialogue. Wait while refreshing completes.
In the Options –> Hide Microsoft Entries.Click Refresh button on the interface OR Close the program and start again

After scanning completes select Logon tab and uncheck all the entries be sure do not un select any Microsoft Entry.Restart system for the changes to take effect.
That is how to remove a virus manually from your computer.

Remove Virus from Computer or USB Drive by Command Prompt

The word  “Virus” is a threat to users of Windows. Users feel uneasy to connect others USB or pen drive to their Computer for the inflections made by Virus. Viruses spread in Computer to Computer through the pen drive or any removable disk drive. Mainly Autorun.inf or many .exe  files like newfolder.exe, ravmon.exe etc affect the documents of your computer. If you try to delete the file from the directory they come back automatically every time and it easily spreads in the computer.

These Autorun or .exe files are written in such a manner that when we try to open or rename a drive a specific program starts as a result we can’t do those works.You can remove viruses from Task Manager. You have to stop the affecting process from “Task Manager” by choosing that process as “End Task” in Task Manager. But the virus programmer are much aware about that so when you want to open “Task Manager” by pressing “Ctrl+alt+del” you will see that the “Task Manager has been disabled by your administrator“.


In this situation there is another process to remove autorun.inf from Command Prompt. That seems more effective. You have go through some commands only. But the Command Prompt may be disabled by the virus. You can download a replacement of the Command Prompt.
However after getting the access of Command Prompt you can apply the following tricks to remove the virus from your computer.


First click the “Start” button and go to “Run“. You can also press “Windows+R“. Type “cmd” there.

Type the following commands in the Command Prompt

• Type “<Drive_name>:” in the command prompt and hit “Enter“. (“Drive_name” is where the problem occurs, it may be any USB drive)
• Type “attrib” and hit “Enter“. (This shows the files that are present in the currently working directory. You can also use the command “dir/w/o/a/p“)
• If there are any file named autorun.inf then go for next steps else the drive is not affected with any autorun.inf file.
• Type “attrib -h -r -s -a *.* ” then hit “Enter“.  (This command removes the Hidden, Read Only, System and Archive attributes over any file)
• After unhiding and removing attributes you can see the files.  So you can delete the file now.
• Type “del <filename>” in the Command Prompt and hit “Enter“. (As for example del autorun.inf)

Now your computer is virus free. Enjoy! Feel free to share your experience with us.

How to recover the deleted default folders in my home folder

In Ubuntu 10.04 you can edit the file ~/.config/user-dirs.dirs to change the location of those folders.

When you've change the file you need to restart nautilus (run 'nautilus -q' in a terminal or log out an in again).

Home folder

 Consequenues

• How will applications that expect them to be present behave?
• Where will the items on my desktop go?

open the file "user-dirs.dirs" using the gedit

/home/.config/user-dirs.dirs

Edit the file if u want to make changes and logout & login to reset.

LTE - The Channel quality indicator (CQI)

The Channel quality indicator (CQI) of the definition

• A combination of modulation scheme and transport block size corresponds to a CQI index
• Each PDSCH transport block ((modulation scheme + transport block size)  CQI index)
• Block occupying a group of downlink physical resource blocks  CSI reference resource, received with a transport block error probability (< 0.1).
•  Highest CQI index between 1 and 15 condition, or CQI index 0 if CQI index 1 does not satisfy the condition,
• In the frequency domain, the CSI reference resource is defined by the group of downlink physical resource blocks corresponding to the band to which the derived CQI value relates.
• For periodic CSI reporting, it is an element of the CSI subframe set linked to the periodic CSI report when that UE is configured with CSI subframe sets.
• An OFDMA frame is divided into K sub channels in the frequency domain and T symbols in the time domain.
• In each OFDMA frame there are T × K slots and each UE may be allocated one or more such slots according to its application requirements.
• The slot on the kth subchannel at the tth symbol  denoted as (kth, tth) slot.
• The CQI of the whole frame is perfectly known at the eNodeB through messages from UEs

Long Term Evolution, Cross layer QoS downlink scheduler, Cross Layer Concept, packet scheduling algorithms

Towards 4g LTE (Long Term Evolution)

1. LTE - evolution of mobile broadband technology that will deliver users the benefits of faster data speeds and new services by creating a new radio access technology that’s optimized for IP-based traffic and offers operators a simple upgrade path from 3G networks.
2. LTE is the name of the 4G efforts being undertaken in Europe.
3. LTE is the result of ongoing work by the 3rd Generation Partnership Project (3GPP), a collaborative group of international standards organizations and mobile-technology companies.
4. 3GPP(3rd Generation Partnership Project), IEEE and 3GPP2 are three major standard development groups that are in tight competition to satisfy 4th generation requirements.

LTE specifications

1.Support scalable bandwidths -1.4, 3.0, 5.0, 10.0 and 20.0 MHz
2. Peak data rate that scales with system bandwidth
 Downlink (2 Ch MIMO) peak rate of 100 Mbps in 20 MHz channel
 Uplink (single Ch Tx) peak rate of 50 Mbps in 20 MHz channel
3. Supported antenna configurations
Downlink: 4x2, 2x2, 1x2, 1x1
Uplink: 1x2, 1x1
4. Spectrum efficiency
Downlink: 3 to 4 x HSDPA Rel. 6
Uplink: 2 to 3 x HSUPA Rel. 6
5. Latency
C-plane: <50 – 100 ms to establish U-plane
U-plane: <10 ms from UE to server
6. Mobility
Optimized for low speeds (<15 km/hr)
High performance at speeds up to 120 km/hr
Maintain link at speeds up to 350 km/hr
7. Coverage
Full performance up to 5 km
Slight degradation 5 km – 30 km
Operation up to 100 km should not be precluded by standard

PACKET SCHEDULING ALGORITHMS

The packet scheduling algorithms normally classified into two categories:
Physical layer-channel quality information (PHY layer - CQI) based packet scheduling algorithm (Max C/I and RR (Round Robin)) and are designed only for single-service situation
Cross-layer based packet scheduling algorithm (PF (Proportional Fairness), M-LWDF (Modified Largest Weighted Delay First) and EXP-rule) which takes into consideration both PHY-layer CQI as well as data link layer buffer queue information.
They satisfy the principle of multi-service directly
M-LWDF (Modified Largest Weighted Delay First) and EXP-rule, considering time delay for better throughput performance can be achieved, but its packet loss rate performance is still insufficient.
EXP/PF scheduling scheme is to schedule the stream service and best-effort service with EXP-rule and PF-rule respectively.

QoS and Radio Bearer

The Bearer class models the dedicated radio bearer. When a downlink (uplink) flow starts, it activates a dedicated radio bearer between eNodeB and UE (UE and eNodeB) and vice versa
Types of bearer:
(1) Guaranteed bit rate (GBR) which is a permanent bearer and
(2) Non-guaranteed bit rate (non-GBR) which is an IP connectivity bearer.
GBR and non-GBR bearers are associated with different bearer-level QoS parameters which is called QoS Class Identifier (QCI).
The QCI is a scalar denoting a set of transport characteristics (bearer with/without guaranteed bit rate, priority, packet delay budget, packet error loss rate)
QCI used to infer nodes specific parameters that control packet forwarding treatment (e.g., scheduling weights, admission thresholds, queue management thresholds, link-layer protocol configuration, etc.

CROSS LAYERING

A number of (physical and medium access layer) parameters are jointly controlled and functioned with higher layer functions like resource allocation, admission control and routing. Optimization method mainly involving PHY and MAC to manage the system resources adaptively 

 by vinayagam D
Cross Layer Concept in LTE scheduling

The eNodeB creates a list of downlink flows having packets to transmit
MAC queue length and CQI feedbacks are stored for corresponding to each flow.
Scheduling strategy, the chosen metric is computed for each flow
The eNodeB assigns each sub-channel to the users in the flow list that presents the highest metric
For each scheduled flow, the eNodeB computes the size of transport block, i.e., the quota of data that will be transmitted at the MAC layer during the current TTI. 

Cross layer QoS downlink scheduler

Design principle of scheduler

• Packet belonging to same SDF but to different UEs are queued in different logical queues.
• Packets in the queue are in the order of arrival time
• Packet are reordered based on earliest delay deadlines sensitive Real Time SDFs
• Only HOL packet PHOL  in each queue is consider in each scheduling decision