For changing directory / to /etc
[root@pc1 /]# cd /etc
One step back /etc to /
[root@pc1 etc]# cd ..
Go to previous working directory
[root@pc1 /]# cd -
Go to current login user home directory
[root@pc1 etc]# cd ~
Show the contents of /etc in single color
[root@pc1 ~]# dir /etc
Show the contents of /etc in different colors with nature of contents
[root@pc1 ~]# Ls /etc
create a folder on root partition
[root@pc1 ~]# mkdir /disk
Create a folder in /disk
[root@pc1 ~]# mkdir /disk/dir
Create multiple folder in multiple directories with single command
[root@pc1 ~]# mkdir /etc/dir1 /var/dir2 /usr/dir3
Create multiple folder in same directory
[root@pc1 ~]# mkdir dir1 dir2 dir3
Copy a file in directory
[root@pc1 disk]# cp file dir
Copy a file from /disk/file and paste it in /disk/dir/
[root@pc1 disk]# cp /disk/file /disk/dir
Copy a directory with –r option
[root@pc1 disk]# cp -r dir dir2
Copy a file from /disk/file and paste it in /etc with myfile name
[root@pc1 disk]# cp /disk/file /etc/myfile
Remove a file
[root@pc1 disk]# rm file
Remove a file with forcefully option
[root@pc1 disk]# rm –f file
Remove a directory with out –r option and you face will an error
[root@pc1 disk]# rm dir
Remove a directory with –r option
[root@pc1 disk]# rm -r /disk
Remove a directory with forcefully option
[root@pc1 disk]# rm -rf dir
Move /etc/dir1 to /disk/ with different name
[root@pc1 disk]# mv /etc/dir1 /disk/mydir
Rename the folder name mydir to dir
[root@pc1 disk]# mv /disk/mydir /disk/dir
Rename the file name with myfile
[root@pc1 disk]# mv file myfile
Read a file page by page with less command
[root@pc1 disk]# less /etc/grub.conf
Read a file page by page with more command
[root@pc1 disk]# more /etc/qrub.conf
Read first ten lines of grub.conf
[root@pc1 disk]# head /etc/grub.conf
Read last ten lings of grub.conf
[root@pc1 disk]# tail /etc/grub.conf
Read first 12 lines with –n option
[root@pc1 disk]# head -n 12 /etc/grub.conf
Read last 11 lines with –n option
[root@pc1 disk]# tail -n 11 /etc/grub.conf
Copy the contents of /etc/grub.conf in /disk/file
[root@pc1 disk]# cat /etc/grub.conf > /disk/file
Append the contents /etc/mtab in /etc/file
[root@pc1 disk]# cat /etc/mtab >> /disk/file
Merging tow commands with pipe sign output of the first command is input of second command
[root@pc1 disk]# cat /etc/squid/squid.conf I more
Count the total lines of squid.conf
[root@pc1 disk]# cat /etc/squid/squid.conf I wc -L
Show only spool words in squid.conf
[root@pc1 disk]# cat /etc/squid/squid.conf I grep spool
Flush the contents of file
[root@pc1 disk]# cat /dev/null > /var/log/messages
Linux Basic Commands
Saturday, July 31, 2010
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Linux
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25 Most Interesting Computer Facts
Here is a collection of 25 Most Interesting Computer Facts featuring Funny Computer Facts,I nternet facts,virus facts and more Computer Fun Facts.
1. 80% of all pictures on the internet are of naked women
2. Another name for a Microsoft Windows tutorial is 'Crash Course'!
3. Bill Gates house was designed using a Macintosh computer.
4. By the year 2012 there will be approximately 17 billion devices connected to the Internet.
5. Domain names are being registered at a rate of more than one million names every month.
6. E-mail has been around longer than the World Wide Web.
7. For every 'normal' webpage, there are five porn pages.
8. In the 1980s, an IBM computer wasn't considered 100% compatible unless it could run Microsoft Flight Simulator*.
9. MySpace reports over 110 million registered users. Were it a country, it would be the tenth largest, just behind Mexico.
10. One of every 8 married couples in the US last year met online.
11. The average 21 year old has spent 5,000 hours playing video games, has exchanged 250,000 e-mails, instant and text messages and has spent 10,000 hours on the mobile phone.
12. The average computer user blinks 7 times a minute, less than half the normal rate of 20.
13. The first banner advertising was used in 1994.
14. The first computer mouse was invented by Doug Engelbart in around 1964 and was made of wood.
15. The first domain name ever registered was Symbolics.com.
16. The world's first computer, called the Z1, was invented by Konrad Zuse in 1936. His next invention, the Z2 was finished in 1939 and was the first fully functioning electro-mechanical computer.
17. There are approximately 1,319,872,109 people on the Internet.
18. There are approximately 1.06 billion instant messaging accounts worldwide.
19. While it took the radio 38 years, and the television a short 13 years, it took the World Wide Web only 4 years to reach 50 million users.
20.70% of virus writers work under contract for organized crime syndicates.
21.A program named “Rother J” was the first computer virus to come into sight “in the wild” — that is, outside the single computer or lab where it was created.
22.The worst MS-DOS virus ever, Michelangelo (1991) attacked the boot sector of your hard drive and any floppy drive inserted into the computer, which caused the virus to spread rapidly.
23.A virus can not appear on your computer all by iself. You have to get it by sharing infected files or diskettes, or by downloading infected files from the Internet.
24. Country with the highest percentage of net users is Sweden (75%).
25. The first popular web browser was called Mosaic and was released in 1993.
1. 80% of all pictures on the internet are of naked women
2. Another name for a Microsoft Windows tutorial is 'Crash Course'!
3. Bill Gates house was designed using a Macintosh computer.
4. By the year 2012 there will be approximately 17 billion devices connected to the Internet.
5. Domain names are being registered at a rate of more than one million names every month.
6. E-mail has been around longer than the World Wide Web.
7. For every 'normal' webpage, there are five porn pages.
8. In the 1980s, an IBM computer wasn't considered 100% compatible unless it could run Microsoft Flight Simulator*.
9. MySpace reports over 110 million registered users. Were it a country, it would be the tenth largest, just behind Mexico.
10. One of every 8 married couples in the US last year met online.
11. The average 21 year old has spent 5,000 hours playing video games, has exchanged 250,000 e-mails, instant and text messages and has spent 10,000 hours on the mobile phone.
12. The average computer user blinks 7 times a minute, less than half the normal rate of 20.
13. The first banner advertising was used in 1994.
14. The first computer mouse was invented by Doug Engelbart in around 1964 and was made of wood.
15. The first domain name ever registered was Symbolics.com.
16. The world's first computer, called the Z1, was invented by Konrad Zuse in 1936. His next invention, the Z2 was finished in 1939 and was the first fully functioning electro-mechanical computer.
17. There are approximately 1,319,872,109 people on the Internet.
18. There are approximately 1.06 billion instant messaging accounts worldwide.
19. While it took the radio 38 years, and the television a short 13 years, it took the World Wide Web only 4 years to reach 50 million users.
20.70% of virus writers work under contract for organized crime syndicates.
21.A program named “Rother J” was the first computer virus to come into sight “in the wild” — that is, outside the single computer or lab where it was created.
22.The worst MS-DOS virus ever, Michelangelo (1991) attacked the boot sector of your hard drive and any floppy drive inserted into the computer, which caused the virus to spread rapidly.
23.A virus can not appear on your computer all by iself. You have to get it by sharing infected files or diskettes, or by downloading infected files from the Internet.
24. Country with the highest percentage of net users is Sweden (75%).
25. The first popular web browser was called Mosaic and was released in 1993.
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Computer
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Conficker Worm Detailed Information & Free Removal Tools
Conficker Worm Detailed Information & Free Removal Tools
Worm:Win32/Conficker.A is a worm that infects other computers across a network by exploiting a vulnerability in the Windows Server service (SVCHOST.EXE). If the vulnerability is successfully exploited, it could allow remote code execution when file sharing is enabled.
How Conficker Virus Installs in Windows?
This worm searches for the Windows executable 'services.exe' and will inject itself into it.
This worm copies itself to the Windows system folder as.dll where is a 5-8 character lowercase alphabetic name such as 'nxyme.dll'.
The worm adjusts the file time of the dropped DLL worm copy to the same as the system's kernel32.dll file time to mask forensic evidence of infection time. The registry is modified to execute the dropped DLL worm copy as a service.
Adds value: "DisplayName"
With data: "0"
To subkey: HKLM\SYSTEM\CurrentControlSet\Services\vcdrlxeu
Adds value: "ServiceDll"
With data: "\nxyme.dll"
To subkey: HKLM\SYSTEM\ControlSet001\Services\vcdrlxeu\Parameters
Once a machine has been infected the worm will patch the exploited function via a simple code hook in order to prevent re-infecting a machine it has already compromised. The worm opens and listens for connection attempts on a randomly chosen port between 1024 and 10000 and bypasses Windows firewall using APIs. The worm also stops the Internet connection sharing service.
It Spreads Via...
Networked Computers
Win32/Conficker.A copies itself into memory and begins propagating to random IP addresses across a network by exploiting a vulnerability in the Windows Server service (SVCHOST.EXE). If the vulnerability is successfully exploited, the worm instructs the target computer to download a copy of the worm from the host computer via HTTP protocol using the random port opened by the worm.
The worm uses the following URLs to determine the computer's geographic location:
getmyip.org
getmyip.co.uk
checkip.dyndns.org
Win32/Conficker.A avoids infecting Ukrainian located computers.
Payloads
1.Creates HTTP Server
The worm opens a random port between 1024 and 10000 and acts like a web server (HTTP server). If the remote machine is exploited successfully, the victim will connect back to the http server and download a worm copy.
2.Resets System Restore Point
The worm may call an API function to reset the computer's system restore point, potentially defeating recovery using system restore.
3.Downloads Files
If the date is after November 25, 2008, this worm will build a URL in the following format and attempt to download a file from it:
/search?q=%d&aq=7
If the date is after December 1, 2008 Win32/Conficker.A will attempt to download a file 'loadadv.exe' from the domain 'trafficconverter.biz'.
Worm:Win32/Conficker.A is a worm that infects other computers across a network by exploiting a vulnerability in the Windows Server service (SVCHOST.EXE). If the vulnerability is successfully exploited, it could allow remote code execution when file sharing is enabled.
How Conficker Virus Installs in Windows?
This worm searches for the Windows executable 'services.exe' and will inject itself into it.
This worm copies itself to the Windows system folder as
The worm adjusts the file time of the dropped DLL worm copy to the same as the system's kernel32.dll file time to mask forensic evidence of infection time. The registry is modified to execute the dropped DLL worm copy as a service.
Adds value: "DisplayName"
With data: "0"
To subkey: HKLM\SYSTEM\CurrentControlSet\Services\vcdrlxeu
Adds value: "ServiceDll"
With data: "
To subkey: HKLM\SYSTEM\ControlSet001\Services\vcdrlxeu\Parameters
Once a machine has been infected the worm will patch the exploited function via a simple code hook in order to prevent re-infecting a machine it has already compromised. The worm opens and listens for connection attempts on a randomly chosen port between 1024 and 10000 and bypasses Windows firewall using APIs. The worm also stops the Internet connection sharing service.
It Spreads Via...
Networked Computers
Win32/Conficker.A copies itself into memory and begins propagating to random IP addresses across a network by exploiting a vulnerability in the Windows Server service (SVCHOST.EXE). If the vulnerability is successfully exploited, the worm instructs the target computer to download a copy of the worm from the host computer via HTTP protocol using the random port opened by the worm.
The worm uses the following URLs to determine the computer's geographic location:
getmyip.org
getmyip.co.uk
checkip.dyndns.org
Win32/Conficker.A avoids infecting Ukrainian located computers.
Payloads
1.Creates HTTP Server
The worm opens a random port between 1024 and 10000 and acts like a web server (HTTP server). If the remote machine is exploited successfully, the victim will connect back to the http server and download a worm copy.
2.Resets System Restore Point
The worm may call an API function to reset the computer's system restore point, potentially defeating recovery using system restore.
3.Downloads Files
If the date is after November 25, 2008, this worm will build a URL in the following format and attempt to download a file from it:
If the date is after December 1, 2008 Win32/Conficker.A will attempt to download a file 'loadadv.exe' from the domain 'trafficconverter.biz'.
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Antivirus
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