Php2s.com Linux Guide

How to Install Secure Shell/ OpenSSH Server on Ubuntu 12.04

Frank Boros — Wed, 11 Jul 2012 12:44:34 +0000

This tutorial shows you how to install, enable and configure Secure Shell (SSH)/ OpenSSH server on Ubuntu 12.04 Server. SSH lets you communicate between two networked computers securely. Because SSH is more secure than Telnet, it is recommended that you use SSH instead of Telnet to communicate, and this tutorial will show you how to install and use it in Ubuntu 12.04

OpenSSH is a FREE version of the SSH connectivity tools that technical users of the Internet rely on.

Installing OpenSSH

To install the OpenSSH server application, and related support files, use this command at a terminal prompt:

[root@php2s ~]# sudo apt-get install openssh-server

To install the OpenSSH client applications on your Ubuntu system, use this command at a terminal prompt:

[root@php2s ~]# sudo apt-get install openssh-client

After installing, you may configure SSH Server by running the command below to OpenSSH config file.

[root@php2s ~]# gksu gedit /etc/ssh/sshd_config

Make all the changes in here and save the file. For instance, the default port SSH listens on is 22. Most SSH severs are set to communicate in Protocol Version 2. You could limit the IP Address SSH Server communicates on by uncommenting ( # ) line ListenAddress x.x .x.x and specifying the IP Address.

You might also want to check the following settings:

RSAAuthentication == YES
Protocol == 2 (make sure this is not a ’1′)
PasswordAuthentication == YES (only if you have not done the Key Authentication part below)
AllowUsers == make sure the users you want to access the machine are in here
PermitRootLogin == NO

Then restart the sshd server:

[root@php2s ~]# sudo /etc/init.d/ssh restart

Save the file when done. Try connecting from a remote computer.

Use the following command to connect to server

ssh user@your-server-ip-address

[root@php2s ~]# ssh frank@192.168.1.109

Here the Ubuntu Server ip is 192.168.1.109, username frank. Put your own server ip to connect.

How do I use a client to connect Server

Assuming that your server hostname is php2s, host ip address 192.168.1.109 and username is frank, you need to type the following command:

# ssh frank@php2s
# ssh frank@192.168.1.109

Lets Set a Hostname for client login
By now you’re no doubt getting sick of typing frank@192.168.1.109 or whatever. It sure would be nice to type something shorter. Let’s fix that.

OpenSSH uses a client configuration file, located at ~/.ssh/config, to simplify some of the tedious typing associated with logging into remote machines. To edit (or create) that file, we’ll use the nano text editor, but you can use vi, emacs, kate or whatever:

nano ~/.ssh/config

The simplest configuration file might look something like this:

Host php2s
HostName 192.168.1.109

This associates the Host php2s with the HostName (or IP address) 192.168.1.109, so now to login you’ll only need to type:

ssh frank@php2s

That’s cool, but let’s add more config to make life more easier, How about this:

Host php2s
HostName 192.168.1.109
User frank

Now all we need to type is:

[root@php2s ~]# ssh php2s

Far out! You can add as much configuration data as you need to this Host, and as many different Hosts as you like. And this shorthand will also work with all the scp examples:

scp file.txt php2s:

To learn more visit the OpenSSH docs, or run man ssh_config.

How to Stop, Start & Restart
To stop ssh server, enter:

[root@php2s ~]# sudo /etc/init.d/ssh stop

To start sshs server, enter:

[root@php2s ~]# sudo /etc/init.d/ssh start

To restart ssh server, enter:

[root@php2s ~]# sudo /etc/init.d/ssh restart

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Install and Manage Virtualbox 4 on headless Ubuntu Server 11.10 without GUI

Frank Boros — Wed, 11 Jul 2012 10:33:05 +0000

This guide explains how you can run virtual machines with VirtualBox 4.1 on a headless Ubuntu 11.10 server. Normally you use the VirtualBox GUI to manage your virtual machines, but a server does not have a desktop environment. Fortunately, VirtualBox comes with a tool called VBoxHeadless that allows you to connect to the virtual machines over a remote desktop connection, so there’s no need for the VirtualBox GUI.

I am using Ubuntu server 11.10LTS 32bit but it should work also with 64bit. The installation can be done on the server locally using tty 1-6 or connecting to the server using SSH client from another computer.

First you need to install some dependencies

dkms
build-essential
linux-headers-”yourversion here” (to know your version type “uname -r”)

To install dependencies

sudo apt-get install dkms build-essential linux-headers-3.0.0-14-generic-pae

Now Virtualbox package need to be downloaded to the server. It can be downloaded on the server by copying (create a text file and scp it to the server) the following link to the server and running it. Alternately, the package can be downloaded on second computer and the .deb package can be copied to server using scp. The below package is for 64bit Ubuntu 11.10 server. Exact link can be copied from this link.

wget http://download.virtualbox.org/virtualbox/4.1.6/virtualbox-4.1_4.1.6-74713~Ubuntu~oneiric_amd64.deb

Install Virtualbox 4.1.6 now

sudo dpkg -i virtualbox-4.1_4.1.6-74713~Ubuntu~oneiric_amd64.deb

if it ask for some dependencies do the following: (perryg was helping me to complete my setup and he recommend me to use the ”–nox11″ when installing virtualbox but I didn’t have that right so I installed all the dependencies and it works)

If you know how to put –nox11 good luck if not the do the following, this will install some X packages but they will be ignored.

sudo apt-get -f install

When you run “sudo apt-get -f install” it should install the dependencies and then virtualbox setup, If the VBox setup does not Start.

Then run the installation again.

sudo dpkg -i virtualbox-4.0_4.0.0-69151~Ubuntu~maverick_i386.deb

After that you have Virtualbox headless installed but you need to add the Extension Pack in order to have vrde and usb support.
First download the Extension Pack

wget http://download.virtualbox.org/virtualbox/4.0.2/Oracle_VM_VirtualBox_Extension_Pack-4.0.2-69518.vbox-extpack

(note that this link is for the 4.0.2 and I installed the 4.0.0, this is only informational you should change all of the command according with your linux version and VirtualBox version that you want to install. So if you install Vbox 4.0.0 you should install ExtcPack 4.0.0 or if you install VBox 4.0.2 you should install ExtcPack 4.0.2).

To install it type: VBoxManage extpack install “the name of the extension Pack file”

For example

VBoxManage extpack install Oracle_VM_VirtualBox_Extension_Pack-4.0.2-69518.vbox-extpack

Now you can create configure and add vrde capabilities to your VMs.

Starting A VM With VBoxHeadless

Regardless of if you create a new VM or import and old one, you can start it with the command:

VBoxHeadless –startvm “Ubuntu 11.10 Server”

(Replace Ubuntu 11.10 Server with the name of your VM.)

VBoxHeadless will start the VM and a VRDP (VirtualBox Remote Desktop Protocol) server which allows you to see the VM’s output remotely on another machine.

To stop a VM, run

VBoxManage controlvm “Ubuntu 11.10 Server” poweroff

To pause a VM, run

VBoxManage controlvm “Ubuntu 11.10 Server” pause

To reset a VM, run

VBoxManage controlvm “Ubuntu 11.10 Server” reset

Create your first VM image, setup memory, boot device etc

VBoxManage createvm –name ubuntu –register
VBoxManage modifyvm ubuntu -memory “2048MB” -acpi on -boot1 dvd -nic1 nat
VBoxManage createvdi -filename ~/.VirtualBox/Machines/ubuntu/ubuntu.vdi -size 20000 -register
VBoxManage modifyvm ubuntu -hdb ~/.VirtualBox/Machines/ubuntu/ubuntu.vdi
VBoxManage registerimage dvd ~/ext/debian-40r6-i386-netinst.iso
VBoxManage modifyvm ubuntu -dvd ~/ext/debian-40r6-i386-netinst.iso

Start a VM with VBoxHeadless

VBoxHeadless – -startvm “Ubuntu 11.10″

Connecting to the VM from a remote machine

The Remote desktop viewer in another Ubuntu machine can be used to connect to the virtual machine running on the server. The server’s ip address should be used on host field. vbox is default username for the virtualbox installed on the server.

To learn more about VBoxHeadless, take a look at

VBoxHeadless –help

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Install, Configure Munin on RHEL/CentOS 6.2/Fedora

Frank Boros — Tue, 10 Jul 2012 11:16:30 +0000

This tutorial shows how to install and configure Munin (network/system monitoring tool) on Linux distributions Fedora/ RHEL/ CentOS 6.2 server.

Munin is a monitoring tool for servers. It uses RRDtool to log and graph data from your servers. The plugin API is very easy to grasp. Actually, I haven’t read the API documentation yet. I just looked at the output of the plugins and it looks easy to achieve. The data can be accessed through the web.

Munin works by polling your servers for the data hence two applications, Munin and Munin Node. The former periodically gathers data (cronned) and the latter serves the data to the former.

[root@php2s ~]# yum –enablerepo=epel install munin munin-node -y

On line 60, change the following to your hostname :

[root@php2s ~]# vi /etc/munin/munin.conf

Original :

# a simple host tree
[x86-06.phx2.fedoraproject.org]
address 127.0.0.1
use_node_name yes

Change to :

# a simple host tree
[centos62.php2s.local]
address 127.0.0.1
use_node_name yes

On line 29, please uncomment and change to your hostname :

[root@php2s ~]# vim /etc/munin/munin-node.conf

Original :

#host_name x86-06.phx2.fedoraproject.org

Change to :

host_name centos62.php2s.local

Change the following and allowed your network to access munin :

[root@php2s ~]# vim /etc/httpd/conf.d/munin.conf

Order Deny,Allow
Deny from all
Allow from 127.0.0.1 192.168.1.0/24

Restart Apache httpd service :

[root@php2s ~]# /etc/rc.d/init.d/httpd restart

Start Munin :

[root@php2s ~]# /etc/rc.d/init.d/munin-node start

Make munin start at boot :

[root@php2s ~]# chkconfig munin-node on

Access to munin with web browser after 5 minutes later.

http://(hostname or IP address)/munin/

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how to Synchronize Time on CentOS 6.2 using NTP

Frank Boros — Mon, 02 Jul 2012 14:42:39 +0000

This tutorial shows, how to install and do Time synchronization on CentOS 6.2 using NTP (Network Time Protocol) manually. The NTP is used to synchronize a pc’s time with a reference time source. Under CentOS / RHEL you can use NTP or OpenNTPD server software. Both package provides client and server software programs for time synchronization.

Install NTP on CentOS

To install the ntp, just enter this command at the terminal:

[php2s@CentOS ~]$ sudo yum install ntp

To make the ntpd start at boot time, use this commands:

[php2s@CentOS ~]$ sudo chkconfig ntpd on

Set your own time zone

After installation, edit the default ntp configuration:

[php2s@CentOS ~]$ sudo nano /etc/ntp.conf

Commented out/remove the default CentOS servers,you can add your own time-servers here to synchronize with, lists:

http://www.pool.ntp.org/en/
http://www.pool.ntp.org/zone/europe or
http://www.pool.ntp.org/zone/north-america

Default NTP time-servers

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server 0.centos.pool.ntp.org
server 1.centos.pool.ntp.org
server 2.centos.pool.ntp.org

This is a really good idea which uses round-robin DNS to return an NTP server from a pool, spreading the load between several different servers. Even better, they have pools for different regions – for instance, if you are in Australia, you can use

server 0.au.pool.ntp.org
server 1.au.pool.ntp.org
server 2.au.pool.ntp.org
server 3.au.pool.ntp.org

instead of use default one.

Please chose pool zone from http://www.pool.ntp.org/en/
Adjusting iptables

NTP uses UDP port 123 to conduct its business, either connecting out to another NTP server or accepting incoming connections. If you have iptables filtering incoming traffic on the main NTP server in your cluster you’ll need to open port 123 to UDP traffic to allow the other servers to connect to it.

You can open port 123 for UDP traffic with the following arguments for iptables:

[php2s@CentOS ~]$ vi /etc/sysconfig/iptables

Add the following rules

-I INPUT -p udp –dport 123 -j ACCEPT
-I OUTPUT -p udp –sport 123 -j ACCEPT

After you are done with the configuration, just start the ntp service:

[php2s@CentOS ~]$ sudo service ntpd start

To check if the NTP service is synchronizing:

[php2s@CentOS ~]$ sudo ntpq -pn

To check the synchronization log:

[php2s@CentOS ~]$ sudo tail -f /var/log/messages

Now compare your time with your systems time

[php2s@CentOS ~]$ date

Thanks for visiting Php2s.

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How to install python 2.7 on CentOS 6.2 with setuptools 0.6c11

Frank Boros — Fri, 22 Jun 2012 05:18:45 +0000

In this example, i will show how to download and install Python 2.7 on CentOS 6.2. Python comes with many RHEL dependancies. You need to install the packages/dependencies before install python.

The following steps will show python 2.7 installation on centos 6.2.

Install packages/dependencies:

[php2s@CentOS ~]$ sudo yum install gccgcc-c++.x86_64 compat-gcc-34-c++.x86_64 openssl-devel.x86_64 zlib*.x86_64 wget make setuptool

Now download the Python 2.7 (In my case, I will download it in tmp directory):

[php2s@CentOS ~]$ cd /tmp/
[php2s@CentOS tmp ~]$ wget http://www.python.org/ftp/python/2.7/Python-2.7.tar.bz2

Switch to the super user (root):

[php2s@CentOS tmp ~]$ su

Extract the downloaded Python 2.7 package:

[root@CentOS tmp ~]$ tar -xvjf Python-2.7.tar.bz2

Move to the Python 2.7 directory and configure the package:

[root@CentOS tmp ~]$ cd Python-2.7
[root@CentOS Python-2.7 ~]$ ./configure

It’s time to actually build the binary from the source code:

[root@CentOS Python-2.7 ~]$ make

Now it’s finally time to install the program:

[root@CentOS Python-2.7 ~]$ make install

Edit the user .bash_profile file:

[root@CentOS Python-2.7 ~]$ nano ~/.bash_profile
replace PATH=$PATH:$HOME/bin
with PATH=$PATH:$HOME/bin:/opt/python27/bin

Reload the .bash_profile:

[root@CentOS Python-2.7 ~]$ source ~/.bash_profile
[root@CentOS Python-2.7 ~]$ echo “/opt/python27/lib” > /etc/ld.so.conf.d/python27.conf
[root@CentOS Python-2.7 ~]$ ldconfig

Check the Python version now

[root@CentOS Python-2.7 ~]$ python

Download & Install Setuptools 0.6c11

The setuptools package allows you to download, build, upgrade, install and uninstall Python packages, very easily.

If you are upgrading a previous version of setuptools that was installed using an .exe installer, please be sure to also uninstall that older version via your system’s “Add/Remove Programs” feature, BEFORE installing the newer version.

Once installation is complete, you will find an easy_install.exe program in your Python Scripts subdirectory. Be sure to add this directory to your PATH environment variable, if you haven’t already done so.

We need to fetch the setuptools from the website:

[root@CentOS Python-2.7 ~]$cd ..
[root@CentOS tmp]$
[root@CentOS tmp]$ wget http://pypi.python.org/packages/2.7/s/setuptools/setuptools-0.6c11-py2.7.egg
Run the setuptools using this command:
[root@CentOS tmp]$ sh setuptools-0.6c11-py2.7.egg

Next, we will install the gevent:

[root@centOS tmp]# yum install libevent.x86_64 libevent-devel.x86_64
[root@centOS tmp]# easy_install-2.7greenlet
[root@centOS tmp]# tar -xvzf gevent-0.13.0.tar.gz
[root@centOS tmp]# cd gevent-0.13.0
[root@centOS gevent-0.13.0]# python2.7 setup.py install

Logout from root user and check the python version for user:

[root@centOS gevent-0.13.0]# exit
[root@centOS user]# python

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Top 10 Free Python PDF Ebooks Download to Learn Python Programming

Sheikh Khalid — Sun, 17 Jun 2012 04:25:08 +0000

Python is a high level programming language which increasingly popular. I have collected 10 free ebooks for python which contains lots of exercises, practices, example programs and many more.

Here I have collected 10 Python ebooks for you which may help you to lean python accordingly.

1. A Byte of Python
A Byte of Python is a beginner’s book on Python by Swaroop C H. “If all you know about computers is how to save text files, then this is the book for you,” the site says.

This book is perfect for any kind of python lover and beginner who wants an easy and progressing way of learning python. This one also comes under my personal recommendation.

Download

2. Learn Python the Hard Way
Learn Python the Hard Way is a beginner’s programming book written by Zed Shaw. It was written for Python 2.6. “The Hard Way is Easier” is exactly what they have coded in their book and more they tell about it is : Have you always wanted to learn how to code but never thought you could? Are you looking to build a foundation for more complex coding? Do you want to challenge your brain in a new way? Then Learn Python the Hard Way is the book for you.
Read The Book

3. How to think like a computer scientist
This book gives you the practical overview relating the real life problems and how to solve them in python. If you really want your brain to do some work and start learning python the scientist way then you should go with this one. you may go slow with this book but you will end up being an hard core programmer in python.
Download

4. The Python Tutorial
The official documentation are always best. Whether you follow some books or not this documentation is MUST to be opened in a browser while you learn python and/or you can have an offline copy of it. Download it form the site.
Download

5. Think Python
Think python will take you deep with awesome examples and make you work on it. This e-book tries to make readers practice each and every example they show up as they progresses and make use of it. You may also like to begin with this e-book.
Download Think Python

6. Python 101
This document is a syllabus for a first course in Python programming. This course contains an introduction to the Python language, instruction in the important and commonly used features of the language,

7. Python Programming
Python Programming is another WikiBooks guide to Python. It’s one of the texts of the MIT course mentioned above.

8. Python Standard Library
This is seriously showing its age as it was originally written for Python 2.0. Although there’s updates they’re incomplete. Its still worth a look though to get a good idea of the Python core.

9. PLEAC Python
Pleac Python like a rapid-fire Python Cookbook with short, concise examples of how to solve a variety of low-level problems. Form string manipulation to database access.

10. Text Processing in Python
I haven’t read it but I thought I’d add it for the sake of completeness.

Extra
Python Web Frameworks
Django Book – A book on Pythons greatest web framework.
Pylons Book – A book on Pythons 3rd best web framework.

How to install Solaris 10 Step by Step Guide Screenshots

Frank Boros — Fri, 15 Jun 2012 06:25:03 +0000

This tutorial shows step by step set of instructions of Solaris 10 installation. Everything you need to get started is here complete with easy to follow picture based instructions. You can Download the Solaris 10 ISO from Oracle.com according to your system configuration.

Oracle Solaris 10 provides proven, enterprise-class security, reliability, and performance for SPARC and x86 systems. It is the best platform to run your mission-critical applications.

Why Solaris?

Guaranteed application and development compatibility
Industry-leading performance and scalability
Proven reliability through built-in fault tolerance
Highest levels of enterprise-class security

Step by Step Installation

Insert the Solaris DVD and select the “Solaris” from “Grub Menu” and press Enter:

Select the “1” and press Enter:

Select Language:

Press Enter within 30 seconds:

Again press Enter:

Press 0 in order to select English as the system language:

Click “Next“:

Select the “Networked” and click “Next“:

Decide here, that you want to use DHCP or manual ip address, I am going to use manual ip address:

Enter the hostname and click “Next“:

Enter the Ip address:

Enter “Netmask“:

Select “Yes” if you want to enable IPv6 but I will not use it:

Select “Default Route”:

Enter the default route information (Ip address):

I will select “No” for Kerberos Security, if you want to use it then select “Yes”:

Select your “Name Service” option, mine is “None“:

Select “NFSv4 Domain Name“:

Select “Time Zone“:

Select your country:

Confirm “Date & Time” and click “Next“:

Enter password for “root” user and click “Next“:

Select “Yes” and click “Next“:

Confirm the “Summary” by clicking on “Confirm“:

Click “Next” to proceed for the next installation tasks:

Accept the default setting by clicking “Next” then press “OK” to continue:

Specify Media:

It will show you the initialization screen:

Accept the “License“:

Select “Type of Install“:

Click “Install Now“ to begin the installation:

Installation will begin:

Installation will take sometime or a lot of time to finish, after reboot, it will ask for username and password:

Select your desired Desktop Environment:

After selection, it will present you with your desired desktop environment:

Now we will configure the internet access on our Solaris 10:

I am using googleDNS (You can use nameserver 8.8.8.8 or 8.8.4.4 any of them), you can use your local or other public dns:

Edit the “nsswitch.conf” file for name service configuration:

Edit this line like this:

Finally, Internet connectivity test:

Now you have connected to internet. Enjoy!

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How to find lost file in Linux using ‘find’ Command

Linus — Wed, 13 Jun 2012 07:16:29 +0000

Lost file can be searched different ways in Linux/Unix System. Linux ‘find’ command can use to locate files in Linux/Unix systems effectively.

Many users use the find tool with just the basic parameters. They get the results that they were looking for. Unfortunately most of the users don’t spend time to learn all about find. If they do, they can make excellent use of this tool and I am sure you would be surprised at the possibilities.

You can search for files by name, owner, group, type, permissions, date, and other criteria. The search is recursive in that it will search all sub-directories too. The syntax looks like this:

find where-to-look criteria what-to-do

All arguments to find are optional, and there are defaults for all parts. (This may depend on which version of find is used. Here we discuss the freely available Gnu version of find, which is the version available on YborStudent.) For example, where-to-look defaults to . (that is, the current working directory), criteria defaults to none (that is, select all files), and what-to-do (known as the find action) defaults to ‑print (that is, display the names of found files to standard output). Technically, the criteria and actions are all known as find primaries.

Search file with name in the whole system:

$ find / -name file_name

This command search for “file_name” in the whole system. The “/” tell the console to search in the whole system. You should run this command as root. If you want to search in your current directory use:

$ find . -name file_nam

Thus the use of “/” searches in the whole system starting from the root directory and must be run as a root. The use of “.” search in the current working directory.

Search file with the specific extension:

$ find . -name “*.txt”

This command search for the files with the extension .txt.

Finding a particular file in your system

$ find / -name ‘filename’ 2>/dev/null
$ find / -name ‘filename’ 2>errors.txt

/ – Start searching from the root directory (i.e / directory)

-name - Given search text is the filename rather than any other attribute of a file ‘filename’. Always enclose the filename in single quotes…

NOTE: 2>/dev/null is not related to find tool as such. 2 indicates the error stream in Linux, and /dev/null is the device where anything you send simply disappears. So 2>/dev/null in this case means that while finding for the files, in case any error messages pop up simply send them to /dev/null i.e. simply discard all error messages.

Alternatively you could use 2>error.txt where after the search is completed you would have a file named error.txt in the current directory with all the error messages in it.

$ find -name ‘met*’

The above command would start searching for the files that begin with the letters ‘met‘ within the current directory and the directories that are present within the current directory.

If no paths are given, the current directory is used. If no expression is given, the expression ‘-print’ is used.

Search based on modification time:
“-mtime” is used to search the files based on modification time. Let’s take a example for a day.

$ find . -mtime 1(find all the files modified exact 1 day)
$ find . -mtime -1(find all the files modified less than a day)
$ find . -mtime +1(find all the files modified more than a day)

Searching with respect to type of the file (-type)

$find . -name ‘temp’
./keepout/temp
./temp
$find . -name ‘temp’ -type d
./temp

Where d – directory, p – named pipe (FIFO), f – regular file and so on

Ignoring case-sensitivity (-iname)

$ find /home/temp -iname ‘index*’

This command searchs for a file starting with string ‘index’ without considering the case of the filename. So all files starting with any combination of letters in upper and lower case such as INDEX or indEX or index would be returned.

Searching for a file based on size

$ find /home/songs -name ‘*.mp3′ -size -5000k
$ find / -size +10000k

First command finds within a directory called /home/songs, only those mp3 files that have a size less than 5000 Kilobytes.

$ find / -mount -name ‘win*’

This command searches for files starting with the letters ‘win’ in their filenames. The only difference is that the mounted filesystems would not be searched for this time. This is useful when you have your Windows partitions mounted by default. And a search for ‘win’ might return many files on those partitions, which you may not be really interested in. This is only one use of -mount parameter.

$ find /mp3-collection -name ‘Metallica*’ -and -size +10000k
$ find /mp3-collection -size +10000k ! -name “Metallica*”
$ find /mp3-collection -name ‘Metallica*’ -or -size +10000k

Boolean operators such as AND, OR and NOT make find an extremely useful tool.
The 1st command searches within the directory /mp3-collection for files that have their names beginning with ‘Metallica’ and whose size is greater than 10000 kilobytes (> 10 MB).
The 2nd command searches in the same directory as above case but only for files that are greater than 10MB, but they should not have ‘Metallica’ as the starting of their filenames.
The 3rd command searches in the same directory for files that begin with ‘Metallica’ in their names or all the files that are greater than 10 MB in size.

How to apply a unix command to a set of files (-exec) ?

$ find . -name ‘*.sh’ -exec chmod o+r ‘{}’ \; -print

This command will search in the current directory and all sub directories. All files ending with .sh extension will be processed by the chmod -o+r command. The argument ‘{}’ inserts each found file into the chmod command line. The \; argument indicates the exec command line has ended.

The end results of this command is all .sh files have the other permissions set to read access (if the operator is the owner of the file).

Searching for a string in a selection of files (-exec grep …).

$ find . -exec grep “hello” ‘{}’ \; -print

Prints all files that contain the string ‘hello’ will have their path printed to standard output.

If you want to just find each file then pass it on for processing use the -q grep option.

$ find . -exec grep -q “hello” ‘{}’ \; -print

Finding Empty files (-empty)

$find . -empty

To delete empty files in the current directory:

$ find . -empty -maxdepth 1 -exec rm ‘{}’ \;

Find Files Under Users & Groups
Users
To locate files belonging to a certain user:

$ find /etc -type f \! -user root -exec ls -l {} \;
-rw——- 1 lp sys 19731 2002-08-23 15:04 /etc/cups/cupsd.conf
-rw——- 1 lp sys 97 2002-07-26 23:38 /etc/cups/printers.conf

Groupies
find can locate files that belong to a specific group – or not, depending on how you use it.
This is especially suited to tracking down files that should belong to the www group but don’t:

$ find /www/ilug/htdocs/ -type f \! -group www

The -nogroup argument means there is no group in the /etc/group file for the files in question.

Locate command

The locate command is often the simplest and quickest way to find the locations of files and directories on Linux and other Unix-like operating systems.

For example, the following command uses the star wildcard to display all files on the system that have the .c filename extension:

# locate “*.c”

The find command is extremely powerful and useful. If you find any question please don’t hesitate to ask. Hope it would be helpful.

Useful more examples
hccfl.edu
Linux.ie

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How to install and configure OpenVZ on CentOS 6.2 / RHEL

Frank Boros — Tue, 12 Jun 2012 07:02:56 +0000

In this tutorial I will show, how to install OPenVZ on CentOS 6.2 and RHEL machine. OpenVZ is a great tool which offers a great virtualization solution with near zero overhead, thus offering great performance. OpenVZ consists of a kernel, some user-level tools, and container templates. Kernel and tools are needed to install OpenVZ, and templates are needed to create containers. Over past couple of years I was using OpenVZ and as excellent low cost solution for Linux services separation and every time I was installing it I had to Google the necessary steps. This led me into writing this simple guide to speedup my future setup. After the installation is finished and system reboots I log in as root and start the modifications.

Get the OpenVZ repository and update “yum”:

#wget -P /etc/yum.repos.d http://download.openvz.org/openvz.repo
#rpm –import http://download.openvz.org/RPM-GPG-Key-OpenVZ
#yum update

Install relevant packages

#yum install openvz-kernel-rhel6 vzctl vzquota bridge-utils -y

Modify relevant kernel (networking) settings to allow proper communication with the VPS’es:

#vi /etc/sysctl.conf

#add these lines for sysctl openvz configuration
net.ipv4.ip_forward=1
net.ipv4.conf.all.rp_filter=1
net.ipv4.icmp_echo_ignore_broadcasts=1
net.ipv4.conf.default.forwarding=1
net.ipv4.conf.default.proxy_arp = 0
kernel.sysrq = 1
net.ipv4.conf.default.send_redirects = 1
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.eth0.proxy_arp=1

Update the new kernel settings:

#sysctl -p

Reboot the machine:

#shutdown -r now

A new Kernel should appear (2.6.32-042stab044.17 in my case) in the Grub menu.
Boot into the new Kernel.

Check that a new interface (venet0) exists:

# ifconfig venet0
venet0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet6 addr: fe80::1/128 Scope:Link
UP BROADCAST POINTOPOINT RUNNING NOARP MTU:1500 Metric:1
RX packets:161 errors:0 dropped:0 overruns:0 frame:0
TX packets:182 errors:0 dropped:12 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:19255 (18.8 KiB) TX bytes:15822 (15.4 KiB)

Also, check the the “vz” service is running:

#/etc/init.d/vz status
OpenVZ is running..

So far, so good – It’s time to get some OS template. Let’s get an Ubuntu 11.10 64bit template:

#wget http://download.openvz.org/template/precreated/ubuntu-11.04-x86_64.tar.gz -P /vz/template/cache

All templates come as archives and reside inside /vz/template/cache directory.

As a best practice it’s a good idea to keep /vz on a separate partition (or a LUN), the partition needs to be big enough to sustain all the VPS’es that are about to be created, so do the calculation according to your needs.

Basic installation is done. You should be able to use the vz* commands and administer your VM’s via the CLI.

For example to create a new VM out of the downloaded template use:

#vzctl create 1 –ostemplate ubuntu-11.04-x86_64 –ipadd 10.0.0.12 –hostname vz03

When 1 is the uid of the VPS.

After the creation, initialize the created VPS via:

#vzctl start 1

You can now enter into the VPS by simply SSH’ing into it or via the following command:

#vzctl enter 1

A very cool (and free) web management which I highly recommend is called OpenVZ Web Panel, can be easily installed via this command:

#wget -O – http://ovz-web-panel.googlecode.com/svn/installer/ai.sh | sh

After the installation, check that the OpenVZ web panel is listening on port 3000:

#lsof -i :3000

An initialization script is provided as part of the installation and is located under: /etc/init.d/owp

Once installed the web panel can be accessed from your browser via:

http://your-ip:3000

Firewall setup

If you want to have the containers on a separate network; such us when you don’t have spare public IP

To add a NAT for the local IPs

iptables -t nat -A POSTROUTING -s 10.0.0.0/24 -o eth0 -j SNAT –to [External IP address]

To forward port 3000 to the vz

iptables -t nat -A PREROUTING -p tcp -d [External IP address] –dport 3000 -i eth0 -j DNAT –to-destination 10.0.0.1:3000
iptables -t nat -A POSTROUTING -s 10.0.0.1 -o eth0 -j SNAT –to [External IP address]

If you dont want to add NAT, you can just allow access to port 12345 from firewall.
Accept tcp packets on destination ports 3000

iptables -A INPUT -p tcp –dport 3000 -j ACCEPT

After you setup your rules, don’t forget to save them

service iptables save

If iptables is not running, you can enable it by running:

system-config-securitylevel

Be sure to modify firewall settings on the hosting machine accordingly to allow access to port 3000.

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How to Configure OSPF and Calculate Cost

Sheikh Khalid — Tue, 12 Jun 2012 05:32:34 +0000

This example shows basic OSPF(Open Shortest Path First) configuration and cost calculation of path based on badhwidth of the link. If multiple routes to a destination are known, routes learned through the protocol with the better administrative distance are preferred.If more than one route to a destination is learned through the preferred protocol, then the preference of routes is based on the metric of the routes.Routes with the better metric are preferred. Open Shortest Path First (OSPF) uses cost as the metric calculated, based on the bandwidth of the link.

Basic OSPF Configuration:

Step 1: Enter privileged EXEC mode:

Router>enable password

Step 2: Enter the configure terminal command to enter global configuration
mode.

Router#config terminal

Step 3: Enter the router ospf command and follow by the process-id.

Router(config)#router ospf process-id

Pick the process-id which is not being used. To determine what ids are being used, issue the show process command.

Router(config)#show process

Step 4: Add the network number, mask and area-id

Router(config-router)#network network-number mask area area-id

The network-number identifies the network using OSPF. The mask tells which bits to use from the network-number, and the area-id is used for determining areas in an OSPF configuration.

Example:

Router(config)#router ospf 100
Router(config-router)#network 192.168.0.0 0.0.255.255 area 3
Router(config-router)#exit
Router(config)#interface Ethernet 0/0
Router(config-if)#ip address 192.168.16.1 255.255.255.240
Router(config-if)#ip ospf priority 100
Router(config-if)#exit
Router(config)#interface Ethernet 0/1
Router(config-if)#ip address 192.168.16.15 255.255.255.240
Router(config-if)#ip ospf priority 20
Router(config-if)#exit
Router(config)#interface Ethernet 0/2
Router(config-if)#ip address 192.168.16.30 255.255.255.240
Router(config-if)#ip ospf priority 15
Router(config-if)#exit
Router(config)#interface Ethernet 0/3
Router(config-if)#ip address 192.168.16.17 255.255.255.240
Router(config-if)#ip ospf cost 10

Repeat this step for all the network numbers.

To turn off OSPF, use the following command.

Router(config)#no router ospf process-id

Configure OSPF Cost Path:

The auto-cost reference-bandwidth command allows you to change the reference bandwidth that OSPF uses to calculate its metrics:

Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#router ospf 87
Router(config-router)#auto-cost reference-bandwidth 1000
Router(config-router)#end
Router#

You can also adjust the OSPF cost of a single interface with the ip ospf cost configuration command:

Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#interface Ethernet0
Router(config-if)#ip ospf cost 31
Router(config-if)#end
Router#

The custom in OSPF networks is to make the link cost inversely proportional to the bandwidth of a link. This isn’t required, but it is common, and it is the default behavior for Cisco routers. The reference bandwidth defines the link speed that has an OSPF cost of 1. By default, the reference bandwidth is 100Mbps.

However, if you have faster links in your network (such as gigabit Ethernet or even OC-3 connections), OSPF can’t give these links a better cost than 1. So you should set the reference bandwidth to at least as high as the fastest link in your network. In fact, you may want to set this value higher than the bandwidth of your fastest link to ensure that you don’t have to reconfigure your whole network when you eventually upgrade some of your core links.

It is important to set the same reference bandwidth on all routers in an area, and preferably throughout the entire network. Recall that OSPF allows every router to calculate its own routing table based on the LSAs that they receive. So, they must all agree on the relationship between costs and bandwidth. Suppose you set the reference bandwidth differently on two routers, causing them to advertise different link costs for their Ethernet interfaces. This could cause seriously strange routing patterns as OSPF will try to avoid using the higher-cost links. It may decide, for example, that a FastEthernet interface on one router is faster than a Gigabit Ethernet interface on the other router.
But there is another interesting problem with the way OSPF calculates its metrics. Suppose your network includes one or more Gigabit Ethernet links in the core and a WAN that provides 9.6Kbps dial backup for the most remote branches. This means that the fastest link is over 100,000 times as fast as the slowest. When this happens, the router will simply apply the maximum link cost of 65,535.

The problem is that the OSPF metric is only 16 bits long, giving it a maximum per-link cost value of 65,535. So, if your fastest link used the emerging 10Gbps Ethernet standard, and you set the cost of this link to 1, then a relatively common 56Kbps serial link would need to have a cost of 178,571. Since this is not possible, OSPF would have to use the maximum link cost of 65,535. This in itself is not a problem. The problem is that your 128Kbps circuits would also need to have the same cost. This could cause some very poor routing patterns.

We suggest using an alternate costing strategy to avoid this problem. The idea is that the cost of a link doesn’t actually have to be 10 times as high just because the link is 1/10 as fast. In fact, this default behavior implies that it is better to go through a succession of 10 FastEthernet links rather than use a single Ethernet, which is probably not true in most cases. So a useful alternative strategy is to use the square root of the bandwidth instead of the bandwidth when calculating the link cost. The result of this strategy would be -

if you use the default costs, then the three fastest links all wind up with a cost of 1. Changing the reference bandwidth to 10Gbps, however, produces impossibly large metrics for the three slowest links (the router will assign them all a link cost of 65,535). So, no matter what reference bandwidth you use, if you retain the default 1/bandwidth cost mode, you will need to manually adjust either the fastest or slowest several link costs.

The second example shows how to change the OSPF cost for a single interface:

Router(config)#interface Ethernet0
Router(config-if)#ip ospf cost 31

If you change the OSPF cost of a link like this, make sure that all of the other routers that connect to this same network segment use the same cost, or strange routing will result. Further, it is usually a good practice to ensure that all of the links of a particular type have the same cost throughout the network, or at least throughout the area. So, if we set the OSPF cost for 10Mbps Ethernet to 31 on this router, we should do the same on the other routers as well.

There are times when you will want to make sure that one particular link is favored, regardless of its actual bandwidth. In this case, you can give this link a special OSPF cost value. However, you will generally want to be careful that all of the devices on this link agree on the cost.

You could also achieve a similar effect by just adjusting the bandwidth statements on each interface, but this will have other consequences as well. It will affect any other routing protocols that you might also be running. It also means that an SNMP query of the interface speed will give an incorrect value, which could confuse network management software. We recommend the direct approach of manually setting the OSPF cost because it is more clear what you are doing and why. This becomes most important when somebody else comes along and wants to change the router configuration. If your cost scheme is not clear, you could cause serious support problems for your successor.

Helpful Commands

Area default-cost
To specify a cost for the default summary route sent into a stub area, use the area default-cost command in router configuration mode. To remove the assigned default route cost, use the no form of this command.

area area-id default-cost cost
no area area-id default-cost cost

Show ip ospf neighbour Command
The show ip ospf neighbour command shows OSPF neighbours (known neighbours can be viewed using this command).

Router#show ip ospf neighbor

The command can once again be expanded further to show a deep-dive per interface view in as much detail as possible. Use the command displayed below.

Router#show ip ospf neighbor {type number} {neighbour id} [detail]

How to configure bind logging with Bind-Chroot on CentOS 6.2

Linus — Sun, 10 Jun 2012 10:56:49 +0000

This article will help you create a bind-chroot configuration to separate daemon messages from users queries on CentoOS 6.2.

Note that with CentOS 6.2 bind chrooting is done by mount points, see mount | fgrep named while named is started ; you must not symlink configurations files and you should edit files directly under /etc. Though, you should not put your configuration directly in /etc/named.conf but include your own files under /etc/named/ using the include directive.

There are two possible configurations:

With a chrooted bind, since log files are physically placed under /var/named/chroot/var/log/, a lazy admin would want to symlink them in /var/log/:

ln -sf /var/named/chroot/var/log/dns.log /var/log/dns.log
ln -sf /var/named/chroot/var/log/dns_queries.log /var/log/dns_queries.log

1. Logging to syslog

1.1 Configure named for syslog
/etc/named.conf: Remove the logging{} block and include your own file

[...]
include “/etc/named/named.conf.local”;

/etc/named/named.conf.local:

[...]
// Do not print-time, it’s redundant with syslog header.
logging {
channel log_dns {
syslog local3;
print-category yes;
print-severity yes;
print-time no;
};
channel log_queries {
syslog local4;
print-category yes;
print-severity yes;
print-time no;
};
category default {log_dns;};
category queries {log_queries;};
category lame-servers { null;};
category edns-disabled { null; };
};

1.2 Configure rsyslog
/etc/rsyslog.conf:

# Don’t forget to add the chrooted log socket.
$AddUnixListenSocket /var/named/chroot/dev/log
if $syslogfacility-text == ‘local3′ then /var/named/chroot/var/log/dns.log
& ~
if $syslogfacility-text == ‘local4′ then /var/named/chroot/var/log/dns_queries.log
& ~

1.3 Configure logrotate
/etc/logrotate.d/named:

Rsyslog must be reloaded before named in order to create the new empty log files after rotation.

/var/named/chroot/var/log/dns.log
/var/named/chroot/var/log/dns_queries.log
/var/named/data/named.run {
missingok
create 0644 named named
postrotate
/bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true
/sbin/service named reload 2> /dev/null > /dev/null || true
endscript
}

2. Logging to files

2.1 Configure named
/etc/named.conf: Remove the logging{} block and include your own file

[...]
include “/etc/named/named.conf.local”;

/etc/named/named.conf.local:

[...]
logging {
channel log_dns {
file “/var/log/dns.log” versions 3 size 10m;
print-category yes;
print-severity yes;
print-time yes;
};
channel log_queries {
file “/var/log/dns_queries.log” versions 3 size 20m;
print-category yes;
print-severity yes;
print-time yes;
};
category default {log_dns;};
category queries {log_queries;};
category lame-servers { null;};
category edns-disabled { null; };
};

Now you can login through file.

To display last lines on dns_queries.log, simply execute the following command :

tail -f /var/log/dns_queries.log

Reference@
Floriancrouzat

How to get a small sample dataset from a mysql database using mysqldump

Frank Boros — Wed, 06 Jun 2012 10:53:54 +0000

In this quick quick tip that will show how you can get a small sample dataset from a mysql database using mysqldump. We frequently need to get a small snapshot from a very big production database to import it into a development or staging database that will not need all the original data; let’s say we need 1,000,000 records from all the tables in the database; we will just use the option –where=”true LIMIT X”, with X the number of records we want mysqldump to stop after.

Simply we will run something like (add whatever other options you need to mysqldump):

mysqldump –opt –where=”true LIMIT 1000000″ mydb > mydb1M.sql

and this will get 1M records from each of the tables in the database. If you want this for a single table you would use something like this:

mysqldump –opt –where=”true LIMIT 1000000″ mydb mytable > mydb_mytable_1M.sql

To restore this, you would use the same as on a regular dump:

mysql -p mydb_stage < mydb1M.sql

This will give you a small number of records that you can use for development, testing, etc. whatever you would need.

Source@

Ducea.com

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Download and Install BackTrack 5 R2 GNOME Screenshots

Linus — Wed, 06 Jun 2012 10:29:06 +0000

This example shows, how to install BackTrack 5 R2 GNOME edition step by step screenshots. BackTrack 5 is a Linux distribution designed for penetration testers and other security professionals, or those who want to mess with all the best security and penetration testing applications the free software community has to offer. BackTrack 5 R2 is the latest edition, officially released March 1 (2012). You have the option of downloading a GNOME 2 or KDE ISO installation image for 32- or 64-bit architectures. I have already written several articles using a 32-bit installation image of the KDE edition. Because the installers of the GNOME and KDE editions are slightly different.

You can download a suitable image from here. Burn it to a CD and boot the computer from it. The boot menu is shown here. By default, it should boot into a live desktop at the command line.

Download BackTrack 5 R2 from Website

Direct Link
BackTrack 5 R2 KDE 64 Bit
BackTrack 5 R2 KDE 32 Bit
BackTrack 5 R2 GNOME 64 Bit Direct Link
BackTrack 5 R2 GNOME 32 Bit Direct Link

To boot into a graphical desktop, type startx, then press the Enter or Return key on the keyboard.

Once in the graphical live desktop, click on the Install BackTrack icon on the desktop. This edition is based on Ubuntu 10.04 LTS, so if you still remember what the installer of that edition of Ubuntu looks like, you should be in familiar territory. The installation process is a simple, point-and-click, 7-step process. The fourth step, shown here, is the disk partitioning step. If your objective is to install it standalone on the computer, select the option shown in the image, and click Forward.

By default, the boot loader is installed in the Master Boot Record (MBR) of the hard drive. Just be sure to verify that.

After the installation has completed successfully, rebooting will drop you to a command line login prompt. Type the username root, the type toor for the password. Note the case. You will be logged in to a command line environment. Type startx to start the graphical desktop. Once you are logged in, be sure to change the default password. To do that, launch a shell terminal and type sudo password. Then type you new password, twice.

This just shows what the desktop looks like.

@Source
BackTrack Linux
LinuxDocs.com

How to install Lighttpd with PHP5 and MySQL on Ubuntu 12.04

Linus — Mon, 04 Jun 2012 03:42:00 +0000

Lighttpd web server is an excellent open-source tool designed for speed with all the essential functions of a web server. Lighttpd is a secure, fast, standards-compliant and very flexible web server designed for high-performance environments. It has a very low memory footprint compared to other webservers and takes care of cpu-load. Its advanced feature-set (FastCGI, CGI, Auth, Output-Compression, URL-Rewriting and many more) make lighttpd the perfect webserver-software for every server that suffers load problems. Lighttpd is more configurable than tHttpd and significantly more efficient than the resource hungry Apache web server, running faster on the same hardware while using less than 1/10th the resources. This tutorial shows how to install Lighttpd on an Ubuntu 12.04 server with PHP5 support (through PHP-FPM) and MySQL support.

In this tutorial I use the hostname server1.example.com with the IP address 192.168.0.100. These settings might differ for you, so you have to replace them where appropriate.

I’m running all the steps in this tutorial with root privileges, so make sure you’re logged in as root:

sudo su

Installing MySQL 5

First we install MySQL 5 like this:

apt-get install mysql-server mysql-client

You will be asked to provide a password for the MySQL root user – this password is valid for the user root@localhost as well as root@server1.example.com, so we don’t have to specify a MySQL root password manually later on:

New password for the MySQL "root" user: Repeat password for the MySQL "root" user:

Installing Lighttpd

Lighttpd is available as an Ubuntu package, therefore we can install it like this:

apt-get install lighttpd

Now direct your browser to http://192.168.0.100/index.lighttpd.html, and you should see the Lighttpd placeholder page:

Lighttpd’s default document root is /var/www on Ubuntu, and the configuration file is /etc/lighttpd/lighttpd.conf. Additional configurations are stored in files in the /etc/lighttpd/conf-available directory – these configurations can be enabled with the lighttpd-enable-mod command which creates a symlink from the /etc/lighttpd/conf-enabled directory to the appropriate configuration file in /etc/lighttpd/conf-available. You can disable configurations with the lighttpd-disable-mod command.

Installing PHP5

We can make PHP5 work in Lighttpd through PHP-FPM which we install like this:

apt-get install php5-fpm php5

PHP-FPM is a daemon process (with the init script /etc/init.d/php5-fpm) that runs a FastCGI server on port 9000.

Configuring Lighttpd And PHP5

To enable PHP5 in Lighttpd, we must modify /etc/php5/fpm/php.ini and uncomment the line cgi.fix_pathinfo=1:

vi /etc/php5/fpm/php.ini

[...]
; cgi.fix_pathinfo provides *real* PATH_INFO/PATH_TRANSLATED support for CGI. PHP’s
; previous behaviour was to set PATH_TRANSLATED to SCRIPT_FILENAME, and to not grok
; what PATH_INFO is. For more information on PATH_INFO, see the cgi specs. Setting
; this to 1 will cause PHP CGI to fix its paths to conform to the spec. A setting
; of zero causes PHP to behave as before. Default is 1. You should fix your scripts
; to use SCRIPT_FILENAME rather than PATH_TRANSLATED.
; http://php.net/cgi.fix-pathinfo
cgi.fix_pathinfo=1
[...]

The Lighttpd configuration file for PHP /etc/lighttpd/conf-available/15-fastcgi-php.conf is suitable for use with spawn-fcgi, however, we want to use PHP-FPM, therefore we create a backup of the file (named 15-fastcgi-php-spawnfcgi.conf) and modify 15-fastcgi-php.conf as follows:

cd /etc/lighttpd/conf-available/
cp 15-fastcgi-php.conf 15-fastcgi-php-spawnfcgi.conf
vi 15-fastcgi-php.conf

# /usr/share/doc/lighttpd-doc/fastcgi.txt.gz
# http://redmine.lighttpd.net/projects/lighttpd/wiki/Docs:ConfigurationOptions#mod_fastcgi-fastcgi
## Start an FastCGI server for php (needs the php5-cgi package)
fastcgi.server += ( “.php” =>
((
“host” => “127.0.0.1″,
“port” => “9000″,
“broken-scriptfilename” => “enable”
))
)

To enable the fastcgi configuration, run the following commands:

lighttpd-enable-mod fastcgi
lighttpd-enable-mod fastcgi-php

This creates the symlinks /etc/lighttpd/conf-enabled/10-fastcgi.conf which points to /etc/lighttpd/conf-available/10-fastcgi.conf and /etc/lighttpd/conf-enabled/15-fastcgi-php.conf which points to /etc/lighttpd/conf-available/15-fastcgi-php.conf:

ls -l /etc/lighttpd/conf-enabled
root@server1:/etc/lighttpd/conf-available# ls -l /etc/lighttpd/conf-enabled
total 0
lrwxrwxrwx 1 root root 33 May 15 19:50 10-fastcgi.conf -> ../conf-available/10-fastcgi.conf
lrwxrwxrwx 1 root root 41 May 15 19:50 15-fastcgi-php.conf -> ../conf-available/15-fastcgi-php.conf
root@server1:/etc/lighttpd/conf-available#

Then we reload Lighttpd:

/etc/init.d/lighttpd force-reload

Testing PHP5 / Getting Details About Your PHP5 Installation
The document root of the default web site is /var/www. We will now create a small PHP file (info.php) in that directory and call it in a browser. The file will display lots of useful details about our PHP installation, such as the installed PHP version.

vi /var/www/info.php

Now we call that file in a browser (e.g. http://192.168.0.100/info.php):

If you get the PHP info page, PHP5 is working, and it’s working through FPM/FastCGI, as shown in the Server API line. If you scroll further down, you will see all modules that are already enabled in PHP5. MySQL is not listed there which means we don’t have MySQL support in PHP5 yet.

Getting MySQL Support In PHP5

To get MySQL support in PHP, we can install the php5-mysql package. It’s a good idea to install some other PHP5 modules as well as you might need them for your applications. You can search for available PHP5 modules like this:

apt-cache search php5

Pick the ones you need and install them like this:

apt-get install php5-mysql php5-curl php5-gd php5-intl php-pear php5-imagick php5-imap php5-mcrypt php5-memcache php5-ming php5-ps php5-pspell php5-recode php5-snmp php5-sqlite php5-tidy php5-xmlrpc php5-xsl

Xcache is a free and open PHP opcode cacher for caching and optimizing PHP intermediate code. It’s similar to other PHP opcode cachers, such as eAccelerator and APC. It is strongly recommended to have one of these installed to speed up your PHP page.

Xcache can be installed as follows:

apt-get install php5-xcache

Now reload PHP-FPM:

/etc/init.d/php5-fpm reload

Installing phpMyAdmin

phpMyAdmin is a web interface through which you can manage your MySQL databases. It’s a good idea to install it:

apt-get install phpmyadmin

You will see the following questions:

Web server to reconfigure automatically: <-- lighttpd Configure database for phpmyadmin with dbconfig-common? <-- No

Afterwards, you can access phpMyAdmin under http://192.168.0.100/phpmyadmin/:

Making PHP-FPM Use A Unix Socket

By default PHP-FPM is listening on port 9000 on 127.0.0.1. It is also possible to make PHP-FPM use a Unix socket which avoids the TCP overhead. To do this, open /etc/php5/fpm/pool.d/www.conf…

vi /etc/php5/fpm/pool.d/www.conf

… and make the listen line look as follows:

[...]
;listen = 127.0.0.1:9000
listen = /tmp/php5-fpm.sock
[...]

Then reload PHP-FPM:

/etc/init.d/php5-fpm reload

Next open Lighttpd’s PHP configuration file /etc/lighttpd/conf-available/15-fastcgi-php.conf and replace the host and port lines with “socket” => “/tmp/php5-fpm.sock”:

vi /etc/lighttpd/conf-available/15-fastcgi-php.conf

# /usr/share/doc/lighttpd-doc/fastcgi.txt.gz
# http://redmine.lighttpd.net/projects/lighttpd/wiki/Docs:ConfigurationOptions#mod_fastcgi-fastcgi

## Start an FastCGI server for php (needs the php5-cgi package) fastcgi.server += ( ".php" => (( "socket" => "/tmp/php5-fpm.sock", "broken-scriptfilename" => "enable" )) )

Finally reload Lighttpd:

/etc/init.d/lighttpd force-reload

Stopping, Starting, and Restarting Lighttpd

As each user has their own lighttpd server, they are also allowed to stop, start, and restart it.

This can be accomplished from SSH with the following commands:

sudo /etc/init.d/lighttpd stop
sudo /etc/init.d/lighttpd start
sudo /etc/init.d/lighttpd restart

Useful Links

Source@
Howtoforge
wiki.dreamhost.com

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How to skip mysql duplicate replication error/counter

Sheikh Khalid — Sat, 02 Jun 2012 13:33:20 +0000

In this example, i will show how to skip MySQL duplicate replication error/counter. MySQL replication stops if there is an error running a query on the slave. The reason is so you can resolve the problem, thus keeping the data consistent with the master.

You can skip such errors, even if this is not recommended, as long as you know really well what are those queries and why they are failing, etc.

A simple way out of this is to run the missing DDLs on the slave and push the counter by a step. This is not recommended as this might cause data inconsistency.

Skip one duplicate error
For example you can skip just one query that is hanging the slave using:

mysql>SET GLOBAL SQL_SLAVE_SKIP_COUNTER=1; START SLAVE;

There might be cases where you will want to skip more queries.

Skip all duplicate errors
Edit my.cnf and add:

slave-skip-errors = 1062

As shown above in my example 1062 is the error you would want to skip.

You can skip also other type of errors, but again don’t do this unless you understand very well what those queries are and what impact they have on your data:

slave-skip-errors=[err_code1,err_code2,...|all]

You can skip all types of errors using the same method abobe, seperating each error code you wish to skip with a comma.

http://dev.mysql.com/doc/refman/5.6/en/error-messages-server.html

Hope the example would be helpful.

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Install and Configure Proftpd Server on RHEL / Fedora / CentOS 6.2

Linus — Sat, 02 Jun 2012 05:05:21 +0000

This tutorial explains how to install and configure Proftpd Server on CentOS 6.2, Fedora Linux and RHEL clones. ProFTPdProFTPd is one of the most popular, secure and reliable FTP server for the Linux operating system. Proftpd uses a single configuration file and it’s very simple to set up. Its configuration syntax is very similar to apache web server.

It offers several functionalities such as:

multiple virtual server
anonymous
authenticated access
chroot jail support
SSL/TLS encryption
RADIUS, LDAP and SQL support etc

Before installation make sure gcc package have installed, for installation follow this posting.

To install Gcc package

yum install gcc

to update

yum update gcc

Download & Install ProFTPD Server

[root@php2s ~]# wget ftp://ftp.proftpd.org/distrib/source/proftpd-1.3.4a.tar.gz

[root@php2s ~]# yum install proftpd -y

Start ProFTPD when the system reboot:

[root@php2s ~]# chkconfig –level 3 proftpd on

To Start, Stop & Restart proftpd ftp service, enter:

[root@php2s ~]# service proftpd start
[root@php2s ~]# service proftpd stop
[root@php2s ~]# service proftpd restart

To reload the configuration file, enter:

[root@php2s ~]# service proftpd reload

Configuring Proftpd

/etc/proftpd.conf – Proftpd configuration file
The default configuration file is located at /etc/proftpd.conf or /usr/local/etc/proftpd.conf, depending on your installation. To edit the configuration file, enter:

[root@php2s ~]# nano /etc/proftpd.conf

This is where you specify access types and read/write permissions, and lots of other neat things. In this section, you’ll walk you through a sample config file step by step and explain how we are setting the server up.

ServerName “Php2s.com”
ServerType standalone
Port 21

ServerName – Sets the name of the server. This is what will be displayed to the connecting users.

ServerType – Sets the server to standalone because that is the type of server we are running. If you do not understand this, please refer back to the “Server Type” section of this document. The alternative to “standalone” is “inetd”.

Port – Determines which port on which to accept ftp connections. This is best left at it’s default of 21 unless you have a good reason to change it.

AuthPAM on
Umask 022
MaxInstances 30
User ftp
Group ftp
DefaultRoot ~

AuthPAM – Used to set whetheror not users with accounts on the host machine can ftp in to their home directories. This is on by default so if you want to disable this type of access, you must specifically do so.

Umask – This sets the default permissions of any file uploaded through the ftp server. More info can be found in the online User’s Guide.

MaxInstances – The maximum number of simultaneous connections you want to allow.

User/Group – These two lines set which user and group you want to run the server as.

DefaultRoot – Note this for security reasons. This line tells the server to force any user who has logged in to see their home directory as the root directory. This will stop people from having access to the entire file system.

AllowOverwrite on

Order allow,deny
Allow from .clarkson.edu
Deny from all

Allow from all

Directory /*

The Directory directive specifies that the options within it are to be applied to the aforementioned directory. In this case, we are looking at /* which encompasses the entire file system. Inside this directive, we have AllowOverwrite set to “on”. This will allow all uses the overwrite files in all directories that they have WRITE permission.

Limit LOGIN

Order allow,deny states the precedence of the allow and deny directives. We have set up this example server to only allow connections from someone comming from the domain .clarkson.edu. We then Deny access to everyone. You may be wondering how people at Clarkson can access this server if we have denied access to all. Well, because allow is of higher precedence than deny, when someone tried to connect from clarkson they are allowed because they fit the “Allow from .clarkson.edu” rule. However, when someone comes from .aol.com they will not fit the Allow rule, and will then be checked against the deny rule and since it is set to “Deny from all” the AOL user will be denied.

Limit WRITE

This directive, as we’ve set it up, allows all users of ther server to write. This is known as a global directive because it is not found inside another directive such as a user directive or a directory directive. This means that it applies to ALL users who do not have their own Limit WRITE directive. If you do not set this globaly, your users will not be able to do anything but read files on your server.

User ftp
Group ftp
UserAlias anonymous ftp
MaxClients 10
RequireValidShell no
AccessGrantMsg “Welcome to my FTP Server!”

Deny from all

Anonymous:

This directive sets up an anonymous login and sets the default directory for anonymous login to be /home/ftp/. The User/Group directives here just specify who you want an anonymous user to log in as. root is OBVIOUSLY a horrible choice for this one!! UserAlias just says “Treat the user called ftp as if he were the user anonymous”. MaxClients states that only 10 anonymous users are allowed to connect at a time. RequireValidShell is off. This is so that anonymous users will not need a login name and password to connect. AccessGrantMsg just shows the anonymous users a message after they have logged in. You can also point this to a file by simply using a filename with (no quotes) instead of a message.

The Limit directive here prevents ANY anonymous user from writting to anything. This ensures that they cannot mess anything up.

Hope this example would be helpful.

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Install Samba & Configure Network Share on Ubuntu 12.04 (GUI Mode)

Sheikh Khalid — Thu, 24 May 2012 10:41:33 +0000

In this example, I will show how to install samba and configure network share on Ubuntu 12.04 using GUI(graphical user interface) mode. Samba is a graphical user interface to help with configuration and management, there are several GUI interfaces to Samba available, for me the most simple and powerful one of these tools is samba server configuration tool.

Installing Samba on Ubuntu:

1- Install Samba files

First thing we need to do is to install samba, go to Software center in Ubuntu and search for samba then install the package. If you want to install it via terminal then copy this command :

sudo apt-get install samba samba-common

2- Install some dependencies for Configuration tools (don`t forget to install python-glade2)

sudo apt-get install python-glade2

3- Installing Samba Server configuration Tool :

Now install the graphical interface System-config samba

sudo apt-get install system-config-samba

4- Add a Linux/Unix user:

adduser pirat9

5- Make a Linux/Unix password for user pirat9

passwd pirat9

6- Now open samba configuration tool.

7- Add the folder you want to share and setup the permissions access.

Setup the permissions access

8- Now before to connect to the share, you have to create the samba user :

sudo smbpasswd -a pirat9
New SMB password
retype New SMB Password

Now the configuration is done.

Tip: You can chose any directory you want to share by right click on the folder directory and open the share options

And activate share:

9- Now, let`s test if samba share is working from another Linux Machine, in my case will try to connect from LinuxMint12 machine to Ubuntu 12.04 machine where we just installed samba, from menu open connect to server and type the details of your Ubuntu machine

10-

11-

12- Connect from windows (XP/Vista/7)

Hope the article would be useful.

Source

How to install MATE Desktop Environment on Ubuntu/Fedora

Sheikh Khalid — Wed, 23 May 2012 10:24:54 +0000

Linux MATE can provide the same desktop experience as Gnome2. Perberos initially forked Gnome 2 and called the project MATE. Users and developers were successful at running MATE in Arch Linux and due to popular demand Perberos made it easier for MATE to compile under Debian. Many gnome2 users have shifted to Xfce to avoid gnome3. MATE can give you same old experience.

Installation of MATE is simple as packages are available for many distros. Installation instructions are available on site.
Fedora
Ubuntu
Debian
Linux Mint
Salix OS/Slackware
Archlinux

Installation

Fedora 16

yum install http://dl.dropbox.com/u/49862637/Mate-desktop/mate-desktop-fedora/releases/16/noarch/mate-desktop-release-16-5.fc16.noarch.rpm -y
yum groupinstall MATE-Desktop -y

Ubuntu 12.04

add-apt-repository “deb http://packages.mate-desktop.org/repo/ubuntu precise main”
sudo apt-get update
sudo apt-get install mate-archive-keyring
sudo apt-get update
sudo apt-get install mate-core
sudo apt-get install mate-desktop-environment

Once successfully installed you can login to MATE desktop environment.

Uninstall
Fedora

yum groupremove MATE-Desktop

Ubuntu

apt-get remove mate-desktop-environment
apt-get remove mate-core
apt-get remove mate-archive-keyring
apt-get autoremove

Hope the example would be helpful.

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How to install NVIDIA drivers on CentOS 6.2 / Scientific Linux 6.2

Sheikh Khalid — Wed, 23 May 2012 08:38:03 +0000

In this example, i will show how to intall NVIDIA drivers on CentOS 6.2 / Scientific Linux 6.2 or RHEL clones. By default, RHEL clones such as CentOS 6.2 and SL 6.2 assign the nouveau X11 driver to NVIDIA graphics card. nouveau is a fine driver, miles away from the old nv; however if you want 3D performance (or a compiz powered desktop) you’ll need to turn to NVIDIA and its closed source drivers.

CentOS official repositories don’t contain packages for NVIDIA closed source driver so one needs to add a third party repository that has the driver available, such as the ELRepo repository.

Adding the ELRepo consists of importing the public GPG key and installing the repository:

# rpm --import http://elrepo.org/RPM-GPG-KEY-elrepo.org  
# rpm -Uvh http://elrepo.org/elrepo-release-6-4.el6.elrepo.noarch.rpm

Having added the repository we can finally install the driver (yum pulls nvidia-x11-drv as a dependency) and reboot:

# yum install kmod-nvidia # reboot

Know Issues
By installing NVIDIA closed source drivers, the plymouth graphical boot will no longer be available. In other worlds, the pretty CentOS and SL logos on a black background will be replaced by a bottom horizontal progress bar.

The following link might be useful

http://elrepo.org/tiki/kmod-nvidia

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How to configure network using CLI ang GUI in Ubuntu 12.04

Sheikh Khalid — Wed, 23 May 2012 08:17:38 +0000

In this example I will show how to setup network configuration using command line and graphical tool in Ubuntu 12.04. To start accessing internet or sharing other resources on the network you have to configure TCP/IP settings of you ethernet card. In ubuntu you can configure network settings through GUI and CLI. It can be a difficult task for newbie user who is switching from other OS to ubuntu as the look and feel of ubuntu will be different in comparison of other OS (specifically windows). In this tutorial we will be seeing how to configure TCP/IP setting via GUI as well as CLI.

Before starting the configuration part, you have to know whether you will be configuring IP manually or IP will be assigned directly through DHCP server.

In case of manual IP assignment you should know IP address, subnet mask, gateway and DNS. In this tutorial I am using following information. Remember you don’t require it in case of DHCP configuration.

IP : 192.168.1.100 NETMASK : 255.255.255.0 GATEWAY : 192.168.1.1 BROADCAST : 192.168.1.255 NETWORK : 192.168.1.0 DNS : 8.8.8.8

Method 1 : Configure network GUI mode

Step 1 : First find out the network interface to configure. Open a terminal and run ifconfig

ifconfig

Result will be something similar to below screenshot.

Step 2 : We will be assigning IP address to eth0 adapter. To do the same Click on “System Setting” and select “Network”

Step 3 : As eth0 is wired connection click on “wired”. Choose “ON” option and click on “Configure” button.

Step 4 : Go to “IPv4 Settings” tab. In case of DHCP / Automatic configuration choose “Automatic (DHCP)” option in “method”

In case of manual configuration select “Manual” option in “method”. Click on “Add” button. Enter IP Address, netmask and gateway information. Also enter DNS Server. In this example I am using google DNS server’s IP.

After finishing it up click on “Save” button.

To confirm the setting again run “ifconfig” command and check the “eth0″ interface settings. In case of successful configuration you will see something like below screenshot.

Method 2 : Configure network CLI Mode

Step 1 : First find out the network interface to configure. Open a terminal and run ifconfig

ifconfig

Result will be something similar to below screenshot.

Step 2 : We will be assigning IP address to eth0 adapter. Open a terminal and type

sudo vi /etc/network/interfaces

Step 3 : Now you need to add eth0 information in this file.
In case of DHCP / Automatic IP assignment enter following line and save this file.

iface eth0 inet dhcp

In case of manual IP assignment enter following line and save this file.

iface eth0 inet static
address 192.168.1.100
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1

To configure DNS, enter following command. Remember to run it through “root” user

echo “nameserver 8.8.8.8″ >> /etc/resolve.conf

Step 4 : Now run following command to start eth0 interface

sudo ifup eth0

Step 5: To confirm the setting again run “ifconfig” command and check the “eth0″ interface settings. In case of successful configuration you will see something like below screenshot.

Hope that would be helpful for you.

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