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tutorial - Ext4 support on OpenSuse 11.1

Kernel 2.6.28 Released

Torvald released the final version of Linux Kernel 2.6.28. It's not a big change since RC 9, but it finally appeared as final after lots of discussion on LKML whether to postpone the release or release earlier and make the merge window longer as the developers goes on long holidays.

Here's some summary of Kernel 2.6.28 (taken from KernelNewbies): Linux 2.6.28 adds the first version of Ext4 as a stable filesystem, the much-expected GPU memory manager which will be the foundation of a renewed graphic stack, support for Ultra Wide Band (Wireless USB, UWB-IP), memory management scalability and performance improvements, a boot tracer, disk shock protection, the phonet network protocol, support of SSD discard requests, transparent proxy support, several new network drivers, controlable IO CPU affinity, high-resolution poll()/select(), support of a minimal "dummy" policy in SELinux, tracing improvements, x86 x2APIC support, a fb driver for VIA UniChrome devices, Mitac Mio A701 ARM-based smartphone support, some new drivers, improved device support, and many other small improvements and fixes.

More on the detailed can be viewed at KernelNewbies. The official announcement are here and here

Kernel Compilation:

1) Make sure you have all the required lib for kernel compilation
2) Download the latest kernel from www.kernel.org (2.6.28)
3) Untar the kernel source and move the folder (linux-2.6.28) under /usr/src/
4) Fire Following commands from /usr/src/linux-2.6.28 folder

# make xconfig

This will open a window where you can search for "ext4", select the ext4 options and save the changes (shown below)

# make rpm

5) This is will take some time for source compilation and making rpm file
Now go to — /usr/src/packages/RPMS/i386 where you will find the rpm file, install this rpm file using following command...

# rpm -ivh kernel-2.6.289pae-1.i386.rpm
[DO NOT UPGRADE YOUR EXISTING KERNEL BY USING rpm -Uvh, instead install the new kernel using rpm -ivh]

This will install all the required files like vmlinuz,system.map, etc .. into your /boot folder

# mkinitrd -- This will create /boot/initrd-2.6.28-9-pae file which is required during booting of new kernel and you should see something like ...

Kernel image:   /boot/vmlinuz-2.6.28-9-pae
Initrd image:   /boot/initrd-2.6.28-9-pae
Root device:    /dev/disk/by-id/ata-ST3802110A_9LR2AE39-part2 (/dev/sda2) (mounted on / as ext3)
Resume device:    /dev/disk/by-id/ata-ST3802110A_9LR2AE39-part7 (/dev/sda7)
Kernel Modules:    scsi_mod libata sata_sil hwmon thermal_sys processor thermal pata_atiixp ata_generic ide-core atiixp ide-pci-generic fan jbd mbcache ext3 edd crc-t10dif sd_mod usbcore ohci-hcd uhci-hcd ehci-hcd hid usbhid
Features:       block usb resume.userspace resume.kernel
Bootsplash:    openSUSE (1024x768)
51347 blocks

6) Go to and edit the following file to add the new kernel to boot menu
# vi /boot/grub/menu.lst and add the following lines to it

title openSUSE 11.1 (2.6.28)
root (hd0,5)
kernel /boot/vmlinuz-2.6.28-9-pae root=/dev/sda2 vga=0×317 resume=/dev/sda7 splash=silent showopts
initrd /boot/initrd-2.6.28-9-pae

You can also install new kernel using Yast tool (system -> Boot Loader).

7) Now install the grub using following command
# grub-install /dev/sda
[Check you drive here or install it using YAST tool]

How to use Ext4

One very important thing to keep in mind is that there is NOT Ext4 GRUB support. Well, that wasn't exactly true: There is grub support, but the grub versions used by your current distro don't support it. There's support in the GRUB2 development branch, but only from this commit and ahead. There're available grub2 packages in Ubuntu and debian-derived distros as the grub-pc package. In the 0.9x branch, there's not official support, but there's a Google SoC project that developed support for it, and Google finds patches. So choose yourself. The next release of distros based in Linux 2.6.28 will probably have support in one way or another. The safe option is to keep your /boot directory in a partition formatted with Ext3.

You also need an updated e2fsprogs tool, of course, the latest stable version -1.41.3- is recommended.

Creating a new Ext4 filesystem from the scratch
The easiest one, recommended for new installations. Just update your e2fsprogs package to Ext4, and create the filesystem with mkfs.ext4.

Migrate existing Ext3 filesystems to Ext4
You need to use the tune2fs and fsck tools in the filesystem, and that filesystem needs to be unmounted. Run:

tune2fs -O extents,uninit_bg,dir_index /dev/yourfilesystem

After running this command you MUST run fsck. If you don't do it, Ext4 WILL NOT MOUNT your filesystem. This fsck run is needed to return the filesystem to a consistent state. It WILL tell you that it finds checksum errors in the group descriptors - it's expected, and it's exactly what it needs to be rebuilt to be able to mount it as Ext4, so don't get surprised by them. Since each time it finds one of those errors it asks you what to do, always say YES. If you don't want to be asked, add the "-p" parameter to the fsck command, it means "automatic repair":

fsck -pf /dev/yourfilesystem

There's another thing that must be mentioned. All your existing files will continue using the old indirect mapping to map all the blocks of data. The online defrag tool will be able to migrate each one of those files to a extent format (using a ioctl that tells the filesystem to rewrite the file with the extent format; you can use it safely while you're using the filesystem normally)

Finally do not forget to modify /etc/fstab.

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source:http://linuxpoison.blogspot.com/2009/01/135781757114385.html

tutorial - My Desktop - OpenSuSe 11.1

source:http://linuxpoison.blogspot.com/2009/01/13578175714758.html

tutorial - How to secure PHP with Suhosin

Suhosin is an advanced protection system for PHP installations. It was designed to protect servers and users from known and unknown flaws in PHP applications and the PHP core. Suhosin comes in two independent parts, that can be used separately or in combination. The first part is a small patch against the PHP core, that implements a few low-level protections against bufferoverflows or format string vulnerabilities and the second part is a powerful PHP extension that implements all the other protections.

Features:

Engine Protection (only with patch)
Protects the internal memory manager against bufferoverflows with Canary and SafeUnlink Protection
Protects Destructors of Zend Hashtables
Protects Destructors of Zend Linked-Lists
Protects the PHP core and extensions against format string vulnerabilities
Protects against errors in certain libc realpath() implementations

Misc Features
Protection Simulation mode
Adds the functions sha256() and sha256_file() to the PHP core
Adds support for CRYPT_BLOWFISH to crypt() on all platforms
Transparent protection of open phpinfo() pages
EXPERIMENTAL SQL database user protection

Runtime Protection
Transparent Cookie Encryption
Protects against different kinds of (Remote-)Include Vulnerabilities
disallows Remote URL inclusion (optional: black-/whitelisting)
disallows inclusiong of uploaded files
optionally stops directory traversal attacks
Allows disabling the preg_replace() /e modifier
Allows disabling eval()
Protects against infinite recursion through a configureabel maximum execution depth
Supports per Virtual Host / Directory configureable function black- and whitelists
Supports a separated function black- and whitelist for evaluated code
Protects against HTTP Response Splitting Vulnerabilities
Protects against scripts manipulating the memory_limit
Protects PHP‘s superglobals against extract() and import_request_vars()
Adds protection against newline attacks to mail()
Adds protection against \0 attack on preg_replace()

Session Protection
Transparent encryption of session data
Transparent session hijacking protection
Protection against overlong session identifiers
Protection against malicious chars in session identifiers

Filtering Features
Filters ASCIIZ characters from user input
Ignores GET, POST, COOKIE variables with the following names:
GLOBALS, _COOKIE, _ENV, _FILES, _GET, _POST, _REQUEST
_SERVER, _SESSION, HTTP_COOKIE_VARS, HTTP_ENV_VARS
HTTP_GET_VARS, HTTP_POST_VARS, HTTP_POST_FILES
HTTP_RAW_POST_DATA, HTTP_SERVER_VARS, HTTP_SESSION_VARS
Allows enforcing limits on REQUEST variables or separated by type (GET, POST, COOKIE)
Supports a number of variables per request limit
Supports a maximum length of variable names [with and without indicies]
Supports a maximum length of array indicies
Supports a maximum length of variable values
Supports a maximum depth of arrays
Allows only a configureable number of uploaded files
Supports verification of uploaded files through an external script
Supports automatic banning of uploaded ELF executables
Supports automatic banning of uploaded binary files
Supports automatic stripping of binary content in uploaded files
Configureable action on violation
just block violating variables
send HTTP response code
redirect the browser
execute another PHP script

Logging Features
Supports multiple log devices (syslog, SAPI module error log, external logging script)
Supports freely configureable syslog facility and priority
Supports log device separated selection of alert types to log
Alerts contain filename and linenumber that triggered it
Alerts contain the IP address of the user triggering it
The IP Address can also be extracted from X-Forwarded-For HTTP headers (f.e. for reverse proxy setups)

Installation and Configuration

# cd / tmp
# wget http://download.suhosin.org/suhosin-0.9.27.tgz
# tar xzf suhosin-0.9.23.tgz
# cd suhosin-0.9.23
# ./configure
# make
# make install

The next step is to enable the module in php.ini, editing /etc/php5/apache2/php.ini and adding this line:

extension = suhosin.so

Now just restart Apache and suhosin begin to do it's dirty work:)
For more detail configuration, check here

source:http://linuxpoison.blogspot.com/2009/01/13578175715980.html

tutorial - openSUSE Network Installation/Upgrade Without CD/DVD

Installing or upgrading the opensuse is fairly easy using CD, or net boot CD but many times it happen the we need to install or upgrade the OS using these media, to solve this problem we got a script called setupgrubfornfsinstall

setupgrubfornfsinstall is a dialog based shell script to prepare remote network installations. The script downloads kernel and initrd of the distribution and creates a boot loader entry for them.

Features:
browse installation sources offered via SLP in your LAN
browse nfs exports (special config file needed then)
support for nfs, ftp and http
install openSUSE from download.opensuse.org
install Fedora from download.fedora.redhat.com
supports both grub and lilo (the latter mostly untested nowadays though)
qemu/kvm support, just run setupgrubfornfsinstall with option —qemu.
supports ssh/vnc installation parameters (SUSE only)

1) Preparing network installation source. use http installation source by mount openSUSE ISO image into apache root folder directory (/srv/www/htdocs/11.1) so, in this case URL becomes - http://172.19.12.36/11.1

2) Download the script, rename it to setupgrubfornfsinstall.sh , make it executable
# chmod +x setupgrubfornfsinstall.sh

3) execute the script
# ./setupgrubfornfsinstall.sh and follow the instruction

4) Choose either x86 or x86_64 architecture.

5) Choose installation source

6) Specify the URL for you Apache where we have set-up the installation folder

7) Select the proper resolution for installation

And after few more wizard, reboot your computer and choose network installation from GRUB menu and it will start the installation from the specified URL.

source:http://linuxpoison.blogspot.com/2009/01/135781757117113.html

tutorial - Website downloader for Linux - HTTrack

HTTrack is a free (GPL, free / free software) and easy-to-use offline browser utility.

It allows you to download a World Wide Web site from the Internet to a local directory, building recursively all directories, getting HTML, images, and other files from the server to your computer. HTTrack arranges the original site's relative link-structure. Simply open a page of the "mirrored" website in your browser, and you can browse the site from link to link, as if you were viewing it online. HTTrack can also update an existing mirrored site, and resume interrupted downloads. HTTrack is fully configurable, and has an integrated help system.

HTTrack uses a web crawler to download a website. Some parts of the website may not be downloaded by default due to the robots exclusion protocol unless disabled during the program. HTTrack can follow links that are generated with basic JavaScript and inside Applets or Flash, but not complex links (generated using functions or expressions) or server-side image maps.

OpenSuse user can use "1 click" installaer to install HTTrack - here
Fedora user can install - yum install httrack
Others can download the source code

This video demonstrates the power of HTTrack ...

source:http://linuxpoison.blogspot.com/2009/01/135781757114746.html

tutorial - Write your own kernel module and insert it into running kernel

So, you want to write a kernel module. You know C, you've written a few normal programs to run as processes, and now you want to get to where the real action is, to where a single wild pointer can wipe out your file system and a core dump means a reboot.

kernel Modules are pieces of code that can be loaded and unloaded into the kernel upon demand. They extend the functionality of the kernel without the need to reboot the system. For example, one type of module is the device driver, which allows the kernel to access hardware connected to the system.

1) Check if you have all the required tools and lib (Linux Kernel headers)for building the kernel modules for this you need - kernel-headers, you can check if it's install or not by using command: # rpm -qa | grep kernel-headers, if installed, Typing the following command ...

# ls -d /lib/modules/$(uname -r)/build
Output (OpenSuse 11.1) : /lib/modules/2.6.27.7-9-pae/build

else install the kernel-header from your installation CD/DVD

2) Now, start with the famous "hello World" program, create c file call - hello.c

/*************************************************************/
#include <linux/module.h>
#include <linux/kernel.h>

int init_module(void)
{
    printk(KERN_INFO "Hello world.\n");
    return 0;
}
void cleanup_module(void)
{
    printk(KERN_INFO "Goodbye world\n");
}

/*************************************************************/

3) Create the make file: vi Makefile

obj-m += hello.o
all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

save and close

4) Now compile the module to create - hello.ko using command : # make and you should see something like ...

make -C /lib/modules/2.6.27.7-9-pae/build M=/root/kernel modules
make[1]: Entering directory `/usr/src/linux-2.6.27.7-9-obj/i386/pae'
make -C ../../../linux-2.6.27.7-9 O=/usr/src/linux-2.6.27.7-9-obj/i386/pae/. modules
CC [M] /root/kernel/hello.o
Building modules, stage 2.
MODPOST 1 modules
CC /root/kernel/hello.mod.o
LD [M] /root/kernel/hello.ko
make[1]: Leaving directory `/usr/src/linux-2.6.27.7-9-obj/i386/pae'

you should see lot of news files get created inside the directory, check it "ls" command

5) Load/insert our kernel module into the running kernel (hello.ko) using command: # insmod hello.ko

6) Now let check the information about our module (hello.ko) using command:
# modinfo hello.ko, you should see something like ...

filename:       hello.ko
srcversion:     A59CC2D814343F3CA40CADF
depends:        built-in
vermagic:       2.6.27.7-9-pae SMP mod_unload modversions 586

7) To list the module currently running inside the kernel : # lsmod

8) To remove the "hello.ko" module: # rmmod hello.ko

9) Check the output of our module by looking at the /var/log/message file, you should find the entries like ..

Jan 11 12:31:48 poison kernel: Hello world.
Jan 11 12:32:26 poison kernel: Goodbye world

source:http://linuxpoison.blogspot.com/2009/01/13578175712252.html

tutorial - How to change DMA settings on Ubuntu

One really common solution to slow, and unreliable playback of DVD is the settings related to DMA which is turn "off" by default.

DMA stands for: Direct Memory Access. DMA allows a piece of hardware to talk directly with the RAM, reading and/or writing independent of the CPU (Central Processing Unit). In other words the hardware can use the system memory, bypassing the CPU, allowing the device to read and write much faster.

By default Ubuntu has DMA turned off (set to 0), this can be changed in the /etc/hdparm.conf file, like so:

1. First make a backup of your hdpram file:

# sudo cp /etc/hdparm.conf /etc/hdparm.conf.original

2. Now edit the file using your favorite text editor, I'm using vi, however you can use the editor of you choice:

# sudo vi /etc/hdparm.conf

3. Now just add the following at the end of the file:

/dev/cdrom {
dma = on
}

4. Once you restart your computer you should have DMA turned on.

[Ref: http://geekybits.blogspot.com/2008/01/dma-and-ubuntu.html]

source:http://linuxpoison.blogspot.com/2009/01/135781757117153.html

tutorial - Top 10 articles of 2008 on linuxpoison

Multimedia support in OpenSuse 11 (MP3, MPEG-4, DiVX, etc.)

Multimedia Support in Fedora 10

Multimedia Support in Ubuntu 8.10 Intrepid Ibex

HowTo install software from Source Code

Multimedia support in OpenSuse 10.3

List of best Linux blogs

Mount Samba share using fstab

HowTo Create a self-signed SSL Certificate for Apache

Howto check disk drive for errors and badblocks

All 235 low-cost webcams supported in Linux thanks to... this man

source:http://linuxpoison.blogspot.com/2009/01/13578175713889.html

tutorial - Filtering the packets at Application level

This tutorial will walk you through setting up a Linux layer 7 packet classifier on CentOS 5.1, this can easily be adapted to any other Linux distribution out there.

L7-filter is a classifier for the Linux Netfilter that identifies packets based on patterns in application layer data. This allows correct classification of P2P traffics.
It can classify packets such as Kazaa, HTTP, Jabber, Citrix, Bittorrent, FTP, Gnucleus, eDonkey2000, etc., that uses unpredictable ports as well as standard protocols running on non-standard ports. It complements existing classifiers that match on IP address, port numbers and so on. http://l7-filter.sourceforge.net/

Read More: here

source:http://linuxpoison.blogspot.com/2009/01/13578175712457.html

tutorial - Execute command at regular intervals

If you anytime need to execute a command once and again and again, you can use watch and tell it to execute the Linux command in a give interval.

The syntax of the command is:

watch [option(s)] command

The default interval of execution of the given command is two (2) seconds, but you define a different interval using the option -n.

Here are two useful uses of watch.

watch -n 5 free -m

Which will show you the use of memory each five seconds.

watch -n 30 vnstat -h

Which will show you the bandwidth used hourly, read more about vnstat.

You can also make watch to highlight any change it detect between two screens of output.

watch -n 30 -d vnstat -h

And if you want to maintain the highlight on, add =cummulative to the -d option, like this:

watch -n 30 -d=cummulative vnstat -h

[Ref: http://www.go2linux.org/repeat-command-continously-at-regular-interval-linux]

source:http://linuxpoison.blogspot.com/2009/01/135781757119423.html

tutorial - Firefox and Linux on top for year 2008 on Linuxpoison

Extracted from Google Analytics

source:http://linuxpoison.blogspot.com/2009/01/13578175717478.html

tutorial - Linux Filesystem event notification using inotify

inotify is a file change notification system—a kernel feature that allows applications to request the monitoring of a set of files against a list of events. When the event occurs (read, write, create, delete,mount, un-mount, etc ..), the application is notified. To be useful, such a feature must be simple to use, lightweight with little overhead and flexible. It should be easy to add new watches and painless to receive notification of events.

This can be a handy tool if you need to monitor some directory for files update and as soon as it got updated you need to do some operation.

There is a tool called inotify-tools, which is a C library and a set of command-line programs for Linux providing a simple interface to inotify

Installation:

Fedora
inotify-tools is available through the Fedora Extras repository. Just do: yum install inotify-tools

Gentoo
inotify-tools is available in Gentoo's official portage tree. It may be masked, in which case read the "MASKED PACKAGES" section of the man page for emerge, then unmask it. Then you can simply: emerge inotify-tools

Ubuntu
sudo aptitude install inotify-tools

Othere
you can donload the source code : here and compile and build your binary using following command
./configure --prefix=/usr && make && su -c 'make install'

Some of the events that can be monitored for are:

IN_ACCESS - read of the file
IN_MODIFY - last modification
IN_ATTRIB - attributes of file change
IN_OPEN and IN_CLOSE - open or close of file
IN_MOVED_FROM and IN_MOVED_TO - when the file is moved or renamed
IN_DELETE - a file/directory deleted
IN_CREATE - a file/directory created
IN_DELETE_SELF - file monitored is deleted

Java api - here

source:http://linuxpoison.blogspot.com/2009/01/135781757117993.html

tutorial - How to logout the user forcefully

The other day a friend of mine was asking me how to stop all users' processes and then logout him.
Well maybe the first thing you need is to send a message to the user, so he can actually save his work.
to do that you may use the command wall to let your users know you are about to log them out.

Now at the given time end all of your users' applications, using pkill

sudo pkill -u username

replace username with every username you have in your system, you can also use.

who | awk '{ printf ("%s",$1 "\n"); }'| grep -v root | xargs -I {} -t pkill -u $1{}

This way you can view all all users' processes, be careful using this.

You can also use the command skill but in its man page it says it is obsolete.

skill -KILL -u username

Use this command carefully, as you may make your users loose their jobs.

[Ref: http://www.go2linux.org/how-to-kill-users-processes]

source:http://linuxpoison.blogspot.com/2009/01/13578175718543.html

tutorial - How to change the running process priority

The kernel determines which processes require more cpu time than others by the process' nice level, also called niceness. The higher the nice level of a process is, the less CPU time it will take from other processes. Nice levels range from -20 (the least “nice” level) to 19. Negative values can only set by root.

Adjusting the nice level is useful when running a non time-critical process that lasts long and uses large amounts of CPU time, such as compiling a kernel, on a system that also performs other tasks. Making such a process “nicer”, ensures that the other tasks, for example a webserver, will have a higher priority.

Calling nice without any parameters prints the current niceness:

nikesh@poison:~> nice
0

Running nice command increments the current nice level for the given command by 10. Using nice -n level command lets you specify a new niceness relative to the current one.

To change the niceness of a running process, use renice priority -p process id, for example:

renice +5 3266

To renice all processes owned by a specific user, use the option -u user. Process groups are reniced by the option -g process group id.

source:http://linuxpoison.blogspot.com/2009/01/13578175718857.html

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