Red Hat Linux Enterprise 5: PC Tips by Anu

Showing posts with label Red Hat Linux Enterprise 5. Show all posts

Friday, May 27, 2011

Friday, December 17, 2010

Frequently I get messages like “I have accidentally deleted myproject. Is there any way to recover it in Linux?” or “I worked reallyhard on that program and managed to deleted it right before submission

How do I recover?”. Well I didn’t really have any idea on “How to actually recover deleted files in Linux”.

A few days back I was designing the new logo for my sitein Inkscape. After finishing the design, I saved the svg filecarefully. And deleted other images which I embedded in the logo. A fewmoments later I realized that I just screwed up myself by deleting allthose files as the svg file is now good for nothing.

I searched a lot on recovering files in Linux but in vain. Then a friend told me about Photorec. I managed to recover all the files usingphotorec. I thought it would be a good idea to let others know andspread a good word about Photorec. Below is a step by step howto onusing Photorec to recover your files.

What is Photorec?

From Photorec website,

PhotoRec(Download for Windows | Download for Linux RPM) is file data recovery software designed to recover lost files includingvideo, documents and archives from Hard Disks and CDRom and lostpictures (thus, its ‘Photo Recovery’ name) from digital camera memory.PhotoRec ignores the filesystem and goes after the underlying data, soit will still work even if your media’s filesystem has been severelydamaged or re-formatted.

For This HowTo

Lets say I had a file download_arrow.png in /home/saini/Desktopwhich I have removed accidentally. Login as root and create a directoryrecover which will be used to store all the recovered files.

Install testdisk/PhotoRec

Photorec comes as a part of testdisk package in Fedora (I hope itssame for other distributions as well). Use yum to install testdisk.

[root@fedora-tips ~]$ yum install testdisk

Launch Photorec

Once you are done with installation. Open a terminal and launch photorec (as root).

[root@fedora-tips recover]$ photorec

Select Hard Disk

If you have more than one hard disk in your system, select the one from which you have deleted the file(s).

Select Partition Type

If your hard disk has Linux partitions, then select [Intel].

Select Filetype Option

Move to [File Opt] and press enter. Here you can disable all filetypes by pressing ’s’ . Use space to toggle the check button. Now sincewe removed a png file, we are going to check only png file type.

Select Options

Photorec also has a list of different options. Under normal circumstances you don’t need to modify them

Select Partition

Move the selector to the partition from which you have removed the file. Then press enter on search.

Select Filesystem Type

If you are using Linux, its going to be ext2/ext3/ext4. So the default selection is file.

Select Space for Analysis

Select free if you didn’t write to that partition after removing the particular file otherwise select whole.

Select a Directory to Recover Files

Now select the path where the recovered files will be stored. Then press ‘Y’.

Recovery Progress

Photorec will show how many files it has recovered.

All recovered file will be stored in the directory selected above.Open them in a file browser and you’ll get the removed file there. Ihope this howto will help you recovering files you accidentally delete

Thanks...

How to recover/HACK Windows Password from Linux?

Friday, December 17, 2010

Anu

How to recover linux password when GRUB is also locked?

Friday, December 17, 2010

Anu

How to recover Linux root password?

Friday, December 17, 2010

Anu

Friday, October 15, 2010

LINUX : How to write GUI Script in BASH?

Friday, October 15, 2010

Anu

When it comes to writing customapplications for servers or desktops on Linux, there are a number of choices oflanguages to use. You can write apps in python, perl, ruby, or even php, amongso many others. Scripts can be written in the shell as well, using bash, zsh,or tcsh, to name a few. Out of all of these, writing scripts in the shell (andbash comes with pretty much every Linux distribution out there), is perhaps theeasiest to pick up and the quickest to write.

The nice thing about a shell scriptis that, in itself, there isn’t much to do as far as programming. Shell scriptsare really just a sequence of commands you would write on the command line. Itdoes support if-then-else type statements; it supports loops; and it can becomequite complex if you want it to be, but it doesn’t have to be.

And, like other languages, shellscripts can have GUI front-ends as well. There are a few different choiceshere: Zenity for the GNOME desktop, kdialog for the KDE desktop, and dialog fora TUI, providing menus and prompts suitable for the CLI. To put the power ofshell scripts into a little perspective, I wrote the entire Annvix operatingsystem install program in bash, using dialog to ask questions about theinstallation.

With Zenity and kdialog, you canwrite scripts that prompt users for input using GUI windows. For instance, toask the user to answer a question with “Yes” or “No” you would use:

zenity--question "Do you wish to proceed?"
rc=$?
if[ "${rc}" == "0" ]; then
answer="yes"
else
answer="no"
fi

and the equivalent in kdialog:

kdialog--yesno "Do you wish to proceed?"
rc=$?
if[ "${rc}" == "0" ]; then
answer="yes"
else
answer="no"
fi

Both Zenity and kdialog will displayfurther information with the –help option, and Zenity has a manpage that can be referenced forhelp.

Another example is in creating aprogress bar. For instance, to show a progress bar while finding all backupfiles in your home directory, you might use:

find. -name '*~' | tee >(zenity --progress --pulsate --title "Findingbackup files" --text "Searching for backup files...")>out.txt
zenity--width 400 --height 100 --title "File list" --text-info--filename=out.txt

kdialog works a little strangelyhere, so the above example doesn’t work so well since find only works inone run, but to illustrate with a little sleep trickery:

ref=$(kdialog--progressbar "Finding backup files" 3)
qdbus${ref} org.kde.kdialog.ProgressDialog.setLabelText "Searching for backupfiles..."
qdbus${ref} Set org.kde.kdialog.ProgressDialog value 1
find. -name '*~' >out.txt
qdbus${ref} Set org.kde.kdialog.ProgressDialog value 2
sleep2
qdbus${ref} Set org.kde.kdialog.ProgressDialog value 3
qdbus${ref} org.kde.kdialog.ProgressDialog.close
kdialog--textbox out.txt 400 100

Both will display a progress bar(quite short lived, for this example) and then will display the output of thefind command (which was redirected to a file called out.txt). Note thatkdialog on KDE3 is different than it is on KDE4 (the above is for KDE4). If youare still using KDE3, communication is done via DCOP, rather than DBUS.

These illustrations are quitesimple, but they demonstrate the possibilities of what can be done with eithertool. Out of the two, I find Zenity to be much simpler to work with, but theyboth work quite well, and it of course depends upon your environment of choice.

GUI programming for shell scripts,with helper programs like Zenity and kdialog, is much easier to accomplish thanGUI programs for other programming environments. If you need to write a programthat requires user interaction, and you also need that interaction to be viathe desktop and not a terminal or shell, then these tools can help realize thatgoal.

CODE :

DOWNLOAD COMPLETE TUTORIAL (Password : hack)

LINUX : How to use/configure VIM for automatic spell checking?

Friday, October 15, 2010

Anu

Vim is a fantastic editor, with alot of tricks up its sleeve. It makes a great programmer’s text editor, a greatquick text file editor, and works wonders in conjunction with certain mailclients like Mutt.

One thing that may be lesser knownabout Vim is that it has built-in spelling support, which can make using it towrite email and documentation even more useful. No more need to hope yourspelling is correct, or double-checking it later with something like ispell oranother text editor.

To enable spelling support, whichwas introduced in Vim 7, use the following command in normal mode:

:setspell spelllang=en_us

Change the local code to whateverlanguage you happen to be writing in. The above is for American English; use“en_ca” for Canadian English, “en_gb” for English in Great Britain, etc.

Once spelling is activated, spellingmistakes and other inconsistencies will be color highlighted when typing ininsert mode; in gVim this will result in squiggly underlines and in Vim itself,will result in highlighted words. This largely depends on your color scheme,but typically misspelled words will be highlighted red, with otherinconsistencies such as improper capitalization being highlighted blue or cyan.

If you are working on code, you mayget tired of seeing all the highlighted misspelled “words” (i.e. function orvariable names), and you can disable spellchecking by using:

:setnospell

Vim offers some command shortcuts tonavigate to misspelled or incorrect words. The [s and ]s keyboardcommands will move you to the previous or next misspelled word, respectively.

To see a suggested list of words in order to correct the spelling, use z=in command mode to get the suggested list of replacement words, for example:

Change"documnt" to:
1"document"
2 "documents"
3 "docent"
...
Typenumber and <Enter> or click with mouse (empty cancels):

If you are like me and use Mutt foremail, with Vim as the editor, you may want spelling enabled by default only ifyou are composing an email.

You can do something like the following if autocmdsupport was compiled into Vim, which it should be for most.

(Some distributionsprovide a minimal Vim and an enhanced Vim; you’ll want the enhanced Vim forthis).

"Only do this part when compiled with support for autocommands.
ifhas("autocmd")
   " disable autoindent, make the background dark, change the colorscheme to
   " suit the dark background, make sure our textwidth is 72 characters and
   " disable line numbering for email
   autocmd FileType mail set noautoindent |
       \ set nosmartindent |
       \ set background=dark |
       \ colorscheme evening |
       \ set textwidth=72 |
       \ set nonumber |
       \ set spell spelllang=en_ca
endif" has("autocmd")

The above has a few more bits thatare nice when using Vim to write email, but the primary point of interest ismatching the autocmd FileType to “mail” and then setting the spell optionaccordingly.

This will enable spelling only when the FileType is “mail”;otherwise spelling is off by default.

Because Vim and gVim make such nicetext editors, having the ability to set spelling support within them makes themthat much better. And being able to customize exactly when it is enabled, andwhen it is disabled by default, really helps to avoid remembering (orforgetting) to set it on your own.

CODE:

DOWNLOAD (Password : QQ)

LINUX : Advance ways of DNS querying with 'dig'

Friday, October 15, 2010

Anu

For a system administrator, havingready access to all kinds of information for troubleshooting or configurationof computers and networks is important. When diagnosing connectivity issues, orsetting up a new Web site or server, being able to accurately get informationfrom DNS can be critical; DNS provides a lot of information that can reallyhelp in this regard.

On Linux, the best tool for this jobis dig, part of the BIND collection of utilities. On Red Hat EnterpriseLinux, CentOS, and Fedora, dig is part of the bind-utils package; you don’tneed to actually have the BIND DNS server installed to make use of theutilities.

CODE:

FULL DOWNLOAD

The dig command-line tool is used toquery DNS name servers for information. It can be the default DNS server asdefined for your system, or it can be any other DNS server you specify,including the root name servers. 

A typical invocation of dig would be asfollows:

$dig google.com
;<<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_4.2 <<>>google.com
;;global options: printcmd
;;Got answer:
;;->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29558
;;flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 13, ADDITIONAL: 2
;;QUESTION SECTION:
;google.com.                   IN      A
;;ANSWER SECTION:
google.com.            226     IN     A       74.125.19.99
google.com.            226     IN     A       74.125.19.103
google.com.            226     IN     A       74.125.19.104
google.com.            226     IN     A       74.125.19.147
;;AUTHORITY SECTION:
.                      55953   IN     NS      c.root-servers.net.
.                      55953   IN     NS      d.root-servers.net.
.                      55953   IN     NS      e.root-servers.net.
.                      55953   IN     NS      f.root-servers.net.
.                      55953   IN     NS      g.root-servers.net.
.                      55953   IN     NS      h.root-servers.net.
.                      55953   IN     NS      i.root-servers.net.
.                      55953   IN     NS      j.root-servers.net.
.                      55953   IN     NS      k.root-servers.net.
.                      55953   IN     NS      l.root-servers.net.
.                      55953   IN     NS      m.root-servers.net.
.                      55953  IN      NS     a.root-servers.net.
.                      55953   IN     NS      b.root-servers.net.
;;ADDITIONAL SECTION:
i.root-servers.net.    604759 IN     A       192.36.148.17
l.root-servers.net.    208308 IN      AAAA   2001:500:3::42
;;Query time: 58 msec
;;SERVER: 192.168.250.12#53(192.168.250.12)
;;WHEN: Wed May 12 18:06:50 2010
;;MSG SIZE rcvd: 347

Dig is quite verbose, so there is alot of information here, and not all of it is useful. The important bits arethe A records pointing to google.com, and the server that was queried (in thiscase 192.168.250.12). The information can be trimmed by specifying certainflags:

$dig google.com +noauthority +noadditional
;<<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_4.2 <<>>google.com +noauthority +noadditional
;;global options: printcmd
;;Got answer:
;;->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55797
;;flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 13, ADDITIONAL: 2
;;QUESTION SECTION:
;google.com.                   IN     A
;;ANSWER SECTION:
google.com.            42      IN     A       74.125.19.104
google.com.            42      IN     A       74.125.19.147
google.com.            42      IN     A       74.125.19.99
google.com.            42      IN     A       74.125.19.103
;;Query time: 0 msec
;;SERVER: 192.168.250.12#53(192.168.250.12)
;;WHEN: Wed May 12 18:09:54 2010
;;MSG SIZE rcvd: 347

Knowing the A record, orauthoritative IP address, is very useful information. But so is knowing whatDNS server is authoritative for that domain name, or knowing which mail serversaccept mail for that domain. This can be done by telling dig to get the NS orMX records; if you want all of them, use the ANY option:

$dig MX google.com +short
200google.com.s9a2.psmtp.com.
300google.com.s9b1.psmtp.com.
400google.com.s9b2.psmtp.com.
100google.com.s9a1.psmtp.com.

The +short option is veryuseful to just provide the answers; in this case, we have the names of the MXrecords with their priority.

Want to do a reverse lookup?

This canbe done with the -x option and specifying an IP address instead of a domainname:

$dig -x 74.125.148.13 +short
s9b1.psmtp.com.

And if you want to see the resultsfrom a different DNS server, use the @ prefix with the DNS server to use:

$dig @ns.isp.com google.com

There is also the TXT record fordomains that can be useful, especially if you wan to look up SPF (Sender PolicyFramework, an email validation system) information. For instance:

$dig TXT google.com +short
"v=spf1include:_netblocks.google.com ip4:216.73.93.70/31 ip4:216.73.93.72/31~all"

The dig utility is very handy,especially when used with troubleshooting. It has a lot of options and a lot ofdifferent things it can do; take a look at the output of dig -h for anidea of the many options available.

CODE:

FULL DOWNLOAD

Thanks...

Tuesday, October 12, 2010

How to use SQUID in Windows as well as LINUX?

Tuesday, October 12, 2010

Anu

If you want to setup yourown proxy on your home computer you are able to do it by using Squid.Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. Itreduces bandwidth and improves response times by caching and reusingfrequently-requested web pages.

Whywould you want to use Squid?

If you travel abroad and you want to browse the Internet as you were home with no restrictions.
If you want to help people that are located in countries like Iran, UAE, Thailand, etc. by allowing them to access restricted sites via your computer.
If you want better performance when browsing your frequently-visited sites.
If are about to get shaped and want to reduce your quota consumption.

InstallSquid on Windows

1. Download Squid for Windows

2. Extract that zip archive, and move the “squid” folder to the root of yourdrive (probably C:\).

3. After moving the squid folder, open “C:\squid\etc\squid.conf” in yourfavorite text editor (not Word).

4. Configure the DNS name servers on the line that says “dns_nameservers” topoint at your ISPs DNS servers.

5. You should lock the access to only certain IP addresses.

Inside the text editor search forthe line “http_access deny all” and change it to “http_access allowall“.

This will make your proxy open and accessible to the world. If youwould like to limit your proxy to certain IP blocks, change “http_accessdeny all” to “http_access allow TRUSTED“.

Add a line (BEFORE thehttp_access line to setup an access control list [ACL]). This ACL line thatdefines TRUSTED IPs should be:

aclTRUSTED src xx.xx.xx.xx yy.yy.yy.yy zz.zz.zz.zz

where xx.xx.xx.xx, yy.yy.yy.yy andzz.zz.zz.zz are allowed IP addresses.

6. Setup “visible_hostname”(normally just the public IP address).

7. Turn off logging by adding these two lines:

access_lognone
cache_store_log none

8. Setup the Squid cache by issuingthe following command: “c:\squid\sbin\squid -D –z” (No quotes).
Setup Squid to run as a service by issuing the following command:“c:\squid\sbin\squid –i”.

InstallSquid on Linux

If you’re using CentOS/Redhat, it’spretty straight forward to setup a proxy.

yuminstall squid
nano -w/etc/squid/squid.conf

Setup the trusted IP addresses inthe same way as for Windows.

Turn off logging by adding these twolines:

access_lognone
cache_store_log none

Save the config file and as rootissue the following command to start the Squid proxy server:

servicesquid start

Important!

You should not run Squid on amachine that you’re worried about or is used for production. Make sureyou take basic security precautions, like moving ftp off the defaultport, using a firewall, etc.

ALSO YOU MUST READ MY PREVIOUS POSTS ON PROXY SERVER :->

LINUX/WINDOWS : How to create your own Proxy Server for Hiding your IP?

All about Proxy Server.

ALSO READ MY POSTS ON "HIDE YOUR IP"

How to Hide your IP address/ (HIDE THE IP) ?

How to trace/detect anonymous IPs?