Install Kernel 3.0.4

It is always good to say that you have latest kernel running in your machine. I have upgraded kernel from debian experimental and testing repositories . That was simple and straight forward. But you get real happy when you build a kernel from the source.

This was my first experience in upgrading kernel to 3.0.4 from source and even I don't know whether I can successfully complete or not. But I did this and love to share my experience with all you guys!

Before dive in to this just walk-through this document to learn about kernel.

TLDP-Linux Kernel

Download the latest kernel from Linux Kernel Archive 

# wget http://www.kernel.org/pub/linux/kernel/v3.0/linux-3.0.4.tar.bz2

Extract the kernel

#  bzip2 -dc linux-3.X.tar.bz2 | tar xvf -

Move to the directory where kernel source code is extracted

# mv linux-3.0.4/

Configure your kernel

Use make menuconfig or make config for configuring your kernel. I tried make menuconfig this will give you text based menus

# make menuconfig

Make the kernel 

# make bzImage 

Making kernel modules 

# make modules

This will compile all the modules for kernel 3.0.1

Install the modules compiled

# make modules_install

This will copy all kernel modules to /lib/modules/3.0.4.

Install the new kernel 

# make install

This will copy files vmlinuz-3.0.4, initrd.img-3.0.4 and config-3.0.4 to your /boot directory.

Execute below command in your shell, if initrd.img-3.0.4 is not created.

# update-initramfs -u -k 3.0.4

Configure your Grub

This document explains how to configure new kernel in grub2. grub users please excuse. Check below link to learn more about grub2

Ubuntu-Grub2

Edit /etc/grub.d/40_custom file and add below configuration for new menu item. Please make sure that you are not removing anything which already present in this file

menuentry 'Ubuntu, with Linux 3.0.4' --class ubuntu --class gnu-linux --class gnu --class os {
        recordfail
        insmod ext2
        set root='(hd0,1)'
        search --no-floppy --fs-uuid --set c933488a-c517-465e-9ecf-4744806b3a7a
        linux   /boot/vmlinuz-3.0.4 root=UUID=c933488a-c517-465e-9ecf-4744806b3a7a ro   quiet splash
        initrd  /boot/initrd.img-3.0.4
}

c933488a-c517-465e-9ecf-4744806b3a7a is the UUID. replace this ID with yours. For more information about UUID, wikipedia is the good source.
Use below command to find the UUID

# blkid

Update your grub configuration

# update-grub

Reboot with new kernel

Now reboot your machine. Once you boot with new kernel, execute uname -a in your shell to find the kernel version.

Linux pranavam 3.0.4 #1 SMP Sun Sep 4 12:28:48 IST 2011 i686 GNU/Linux

Quota report using LDAP and Dict

This script will export all LDAP information including current quota usage. You should use quota dict for quota storage

http://wiki1.dovecot.org/Quota/Dict

LDAP attributes

1. givenName
2. sn
3. uid
4. mail
5. quota

This is the way how script will work :

• Script will collect all information from LDAP database. Using NET::LDAP. http://search.cpan.org/~gbarr/perl-ldap/lib/Net/LDAP.pod
• Script collect data from quota dict for using perl DBI
• Script stores all information in a file 
• Script sent mail to administrator attaching the same report using MIME:Lite. http://search.cpan.org/~rjbs/MIME-Lite-3.027/lib/MIME/Lite.pm

#!/usr/bin/perl

# This script will export LDAP information including current quota usage.
# Install NET::LDAP, DBI, MIME::Lite for running this script.
# You have full freedom to modify this script. This will help me to improve the usage.
# Please feel free to reach me on praveen.velu84@yahoo.com

use Net::LDAP;

use DBI;

use MIME::Lite;

# Create a file for storing data

open (MYFILE, '> /tmp/quota_report.csv');

# Modify connection settings of dovecotdict database

my $dbh = DBI->connect("DBI:Pg:dbname=dovecot;host=localhost", "dovecot", "paassword", {'RaiseError' => 1});

my $sth = $dbh->prepare('SELECT * from quota where username = ?') or die "Couldn't prepare statement: " . $dbh->errstr;

$ldap = Net::LDAP->new("localhost");

# Modify your LDAP connectivity.

$ldap->bind("cn=admin,dc=example,dc=com", password=>"secret");

$mesg = $ldap->search(filter=>"(&(mail=*)(objectclass=posixAccount))", base=>"dc=example,dc=com");

print MYFILE "User_Name;First_Name;Last_Name;Email;LDAP_quota(MB);Quota_Usage(MB);No_of_messages\n";

@entries = $mesg->entries;

foreach $entry (@entries){

                $name = $entry->get_value("uid");

                $fname = $entry->get_value("givenName");

                $lname = $entry->get_value("sn");

                $mail = $entry->get_value("mail");

                $quota = $entry->get_value("quota");

$sth->execute($mail);

@data = $sth->fetchrow_array();

$usedquotamb = ($data[1]/1048576);

$quotausage = int $usedquotamb;

$messages = $data[2];

                print MYFILE $name . ";" . $fname . ";" . $lname . ";" .$mail . ";" . $quota . ";" . $quotausage . ";" . $messages ."\n"

}

close MYFILE;

# Senting mail to administrator. Replace postmaster email id with your email id

my $msg = MIME::Lite->new(

    From    => 'postmaster@example.com',

    To      => 'admin@example.com',

    Subject => 'LDAP quota report',

    Type    => 'multipart/mixed',

);

$msg->attach(

    Type     => 'TEXT',

    Data     => "Dear Sir, \n\nThis is an automated message. Please find attached User Quota Report.\n\nEmail Administrator ",

);

$msg->attach(

    Type     => 'text/csv',

    Path     => '/tmp/to_report.csv',

    Filename => 'quota_report.csv',

);

$msg->send;

$dbh->disconnect;

LDAP to CSV using perl

#!/usr/bin/perl

# This script will export LDAP entry in to a csv file. 

# Install Net:LDAP for running this script. 

# Feel free to contact me on praveen.velu84@yahoo.com

use Net::LDAP;

$ldap = Net::LDAP->new("localhost");

$ldap->bind("cn=admin,dc=example,dc=com", password=>"secret");

# Create a new file "ldapcsv.csv and pipe your query output to this file.  

$outputfile = "ldapcsv.csv";

# Create a new File Handler.

open (FH, ">$outputfile") or die "$!";

# Modify your search query and ldap connection details.

$mesg = $ldap->search(filter=>"(&(mail=*)(objectclass=*))", base=>"dc=example,dc=com");

@entries = $mesg->entries;

foreach $entry (@entries){

        @myuid = $entry->get( 'uid' );

        @givenName = $entry->get( 'givenName' );

        @sn = $entry->get( 'sn' );

        @userPassword = $entry->get( 'userPassword' );

        print "Exporting  @myuid[0] to csv file \n";

print FH "@myuid[0],@givenName[0],@sn[0],@userPassword[0]\n"

}

# Close the file handler.

close(FH);

Creating OpenVPN client certificates using perl script

How this perl scrip will work

1. Accept certificate name through stdin

2. Create vpn certificate

3. Copy certificate and client.ovpn to a temp directory

4. Modify certificate name in client.ovpn configuration

5. Create a zip file of VPN certificate file

6. Remove temp file after creating archive

How can I run this script

1. Configure your openvpn server. You can check below link for configure openvpn

 OpenVPN server configuration

2. Copy the script to a file create_vpn_cert.pl

3. Modify script based on your open vpn configuration

4. Modify the permission to execute script

# chmod +x  create_vpn_cert.pl

5. Execute the script

# perl create_vpn_cert.pl

#!/usr/bin/perl -w 
# This perl script is used to create open vpn certificates.

# Script prompt for certificate name. based on the input script will create certificates /tmp directory

 
use warnings;
use File::Copy;
use Archive::Zip;
use File::Path;
my $zip = Archive::Zip->new(); 

# OUTPUT DIRECTORY FOR ZIP FILE
$outputdir='/tmp/';

# DIRECTORY WHERE client.ovpn is available
$ovpn = '/usr/share/doc/openvpn/examples/sample-config-files/';

#DIRECTORY WHERE KEYS ARE STORED
$keys = '/etc/openvpn/easy-rsa/2.0/keys/'; 

#DIRECTORY WHERE build-key SCRIPT AVAILABLE
$scriptdir = '/etc/openvpn/easy-rsa/2.0/';

#Creating Certificate
print "Enter VPN Certificate name:";
$certname = <STDIN>;
chomp $certname;
print "Creating Certificate $certname";
system ("$scriptdir/build-key $certname");
 

# Copy certificate files to temp folder
mkdir("/tmp/$certname", 0775) || print $!;
copy("$ovpn/client.ovpn","/tmp/$certname") or die "Copy failed: $!\n";
copy("$keys/ca.crt","/tmp/$certname") or die "Copy failed ca.crt: $!\n";
copy("$keys/$certname.crt","/tmp/$certname") or die "Copy failed $certname.crt: $!\n";
copy("$keys/$certname.key","/tmp/$certname") or die "Copy failed $certname.key: $!\n"; 

# Modifying client.ovpn file
my $filein = "/tmp/$certname/client.ovpn";
my $filetemp = $filein.'_'.$$;
open (my $fh_in, "<", $filein) or die;
open (my $fh_out, ">$filetemp") or die;
while (<$fh_in>) { 

    my $x = $_;
    $x =~ s/cert client.crt/cert $certname.crt/g;
    $x =~ s/key client.key/key $certname.key/g;
    print $fh_out $x;
}
close ($filein);
close ($filetemp);
move("$filetemp","$filein");

# Creating archive
$zip->addTree( "/tmp/$certname" );
$zip->writeToFileNamed("/$outputdir/$certname.zip");
print "Created certficte for user in /$outputdir/$certname.zip \n";
 

# Removing tmp directory
rmtree("/tmp/$certname");

exit;

 

Shell script to export roundcube address book to csv

Below shell script will convert roundcube address book to csv. I am using postgresql for roundcube database. ouput csv file can found in /tmp folder

#!/bin/bash

# Roundcube Address book must be stored in PostgreSQL database.

# This script is created by Praveen C. please feel free to contact me on praveen.velu84@yahoo.com-

# for any query. You can modify this script to suit your requirement

# Enter roundcube user_name. Script will query this user in DB and export Address book

USER="user_name"
 

# Export your roundcube database passwor. This password will be used for `psql` command

# This will help us to avoid psql prompt for password

export PGPASSWORD=password

#  Find the `user_id` of the user

echo "COPY(SELECT user_id from users where username='$USER') \
                   TO STDOUT" | psql -h localhost -U roundcube  \

                   -o /tmp/rc_query_id roundcube

# Read user_id stored in file rc_query_id file and store to variable _USER_ID

user_list=`cat /tmp/rc_query_id`
for id in $user_list; do

_USER_ID=$id
done

# Query user contacts in and sent output to csv.

echo "COPY (SELECT name,email,firstname,surname from contacts where user_id=$_USER_ID) \
                     TO STDOUT with CSV HEADER" | psql -h localhost -U roundcube \
                     -o /tmp/$USER.csv roundcube

PHP script to monitor your multiple ISP link connected to firewall

I have configured multiple ISP links in a linux firewall. But it is very difficult for users to understand which like is up or down. I decided to create a simple webpage which gives the status of each link in a  webpage. This will avoid the hassle of login to linux machine as a normal user and running commands with root privilage


You can use php and fping to check your ISP links status. Make sure that fping is installed in your firewall.

For a better appearance I am using images to show status of link
Image Courtesy:  Open ClipArt

Image which I used to show when a link is Active. Image name is  up.png

Image which I used to show when a link is down.  Image name is down.gif

I have copied both images in to folder img. Below is the php script. For checking the ping response I am using OpenDNS IP address as my destination server

<html><head><meta content="text/html; charset=ISO-8859-1" http-equiv="content-type"><title>Link Monitor</title></head><body>

<?

// This is the remote host used for fping. Do not change. I am using OpenDNS IP

$remote_host = "208.67.222.222";

// Add you links in to array. Chang these IP address according to IP addres configured in your firewall. You can  one or more IP address in to array

$isps = array('111.222.333.444','555.666.777.888');

$status = array();

foreach ($isps as $isp) 
{

   $fping = `/usr/sbin/fping -u -S$isp $remote_host`;

   if ($fping == "")

   {

      array_push ($status , "up.png");

   }

   else

   {

      array_push ($status , "down.gif");

   }

}

?>

</br>

<table style="text-align: left; width: 1062px; height: 75px;" border="0" cellpadding="2" cellspacing="2">

<?

$count = 1;

foreach ($isps as $isp) {?>

<tr><td  width=20%><FONT COLOR=black FACE="Geneva, Arial" SIZE=5>Link  <?echo $count?></font></td><td  width=30%><FONT COLOR=Blue FACE="Geneva, Arial" SIZE=5><?echo array_pop($isps);?></font></td><td width=30%><IMG SRC="img/<?echo array_pop($status);?>" height="60" width="61"></td></tr>

<?$count ++;}?>

</table>

</body></html>

Create a virtual HDD using qemu-img

When you create a virtual machine using KVM and virt-manager, virtual HDD will create in /var/lib/libvirt/images/ directory. Unfortunately I dont have enough  space in my / partition.

I faced difficulty in creating virtual HDD in other partion using virt-manager. To work around this issue, I used qemu-image. Using qemu-img you can create a new vitual HDD with any size on any of your partition

 # qemu-img create -f qcow debian.qcow 5G

This will create a Virtual HDD debain.qcow with size 5GB, later then you can select this HDD for installation using virt-manager