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Category Archives: how to

Setting Up A High-Availability Load Balancer (With Failover and Session Support) With HAProxy/Heartbeat On Debian Etch

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Setting Up A High-Availability Load Balancer (With Failover and Session Support) With HAProxy/Heartbeat On Debian Etch

This article explains how to set up a two-node load balancer in an active/passive configuration with HAProxy
and heartbeat on Debian Etch. The load balancer sits between the user
and two (or more) backend Apache web servers that hold the same
content. Not only does the load balancer distribute the requests to the
two backend Apache servers, it also checks the health of the backend
servers. If one of them is down, all requests will automatically be
redirected to the remaining backend server. In addition to that, the
two load balancer nodes monitor each other using heartbeat, and if the
master fails, the slave becomes the master, which means the users will
not notice any disruption of the service. HAProxy is session-aware,
which means you can use it with any web application that makes use of
sessions (such as forums, shopping carts, etc.).

Read more…

Creating Virtual Machines In VMware Server From ISO Files Without Burning CDs/DVDs

How To Upgrade Your Desktop From Mandriva 2007.1 To Mandriva 2008.0

Installing Xen On An Ubuntu 7.10 (Gutsy Gibbon) Server From The Ubuntu Repositories

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Installing Xen On An Ubuntu 7.10 (Gutsy Gibbon) Server From The Ubuntu Repositories

This tutorial provides step-by-step instructions on how to install Xen on an Ubuntu Gutsy Gibbon (Ubuntu 7.10)
server system (i386). You can find all the software used here in the
Ubuntu repositories, so no external files or compilation are needed.

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Setting Up A High-Availability Load Balancer (With Failover and Session Support) With Pound/Keepalived On Debian Etch

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Setting Up A High-Availability Load Balancer (With Failover and Session Support) With Pound/Keepalived On Debian Etch

This article explains how to set up a two-node load balancer in an active/passive configuration with Pound
and keepalived on Debian Etch. The load balancer sits between the user
and two (or more) backend Apache web servers that hold the same
content. Not only does the load balancer distribute the requests to the
two backend Apache servers, it also checks the health of the backend
servers. If one of them is down, all requests will automatically be
redirected to the remaining backend server. In addition to that, the
two load balancer nodes monitor each other using keepalived, and if the
master fails, the slave becomes the master, which means the users will
not notice any disruption of the service. Pound is session-aware, which
means you can use it with any web application that makes use of
sessions (such as forums, shopping carts, etc.).

Read more…

How To Upgrade Your Desktop From Ubuntu Studio 7.04 To 7.10

Installing Songbird 0.3 Developer Pre-Release On Ubuntu 7.10 (Gutsy Gibbon)

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Installing Songbird 0.3 Developer Pre-Release On Ubuntu 7.10 (Gutsy Gibbon)

This guide shows how to install the Songbird media player
(0.3 Developer Pre-Release) on an Ubuntu 7.10 (Gutsy Gibbon) desktop.
Songbird is a free software audio player with media database
capabilities written using XUL and VLC, with an interface similar to
Apple’s iTunes. From the Songbird web site: “Songbird
is a desktop media player mashed-up with the Web. Songbird is committed
to playing the music you want, from the sites you want, on the devices
you want, challenging the conventions of discovery, purchase,
consumption and organization of music on the Internet.”

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Monitoring Tomcat 5.0 on Ubuntu

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Monitoring Tomcat 5.0 on Ubuntu

This document describes how to set up and enable Hyperic HQ for monitoring
on Ubuntu and Tomcat. The resulting system provides a comprehensive, web-based
Systems Management Software. It’s the next stage of classical monitoring and
able to manage all kinds of operating systems, web servers, application servers
and database servers. The install comes prepared to monitor almost 70 different
technologies natively and provides many detailed features. For brevity sake, I
won’t list all of them here.
Hyperic HQ is available as an open source distribution licensed under the GPL
v2.

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The Perfect Desktop – Ubuntu Studio 7.10

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The Perfect Desktop – Ubuntu Studio 7.10

This document describes how to set up an Ubuntu Studio 7.10 desktop.
The result is a fast, secure and extendable system with focus on
multimedia creation – the real-time (RT) kernel is installed by
default. It provides all you need for daily work and entertainment.

Read more…

Using Bash Script to Mass Create Users And Change Passwords

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These two scripts are very important for the system admin who regularly works with mail servers and somehow forgets to backup his system username and password! Let’s say somehow we lost the usernames and passwords of the mail server. In this case the admin has to manually create all the users and then change the passwords for all the users. Tedious job. Let’s make our life easier.

First create a file which contains all the user name. Something like this:

nurealam
nayeem
mrahman
farid
rubi
sankar

Save the file as userlist.txt. Now create the following bash file:

#!/bin/sh
for i in `more userlist.txt `
do
echo $i
adduser $i
done

Save the file and exit.

chmod 755 userlist.txt

Now run the file:

./userlist.txt

This will add all the users to the system. Now we have to change the passwords. Let’s say we want username123 as password. So for user nayeem the password will be nayeem123, rubi123 for user rubi and so on.

Create another bash file as follows:

#!/bin/sh
for i in `more userlist.txt `
do
echo $i
echo $i"123" | passwd –-stdin "$i"
echo; echo "User $username’s password changed!"
done

Run the file. All the passwords are changed.

If you want to force all your users to change password, use the following code:

Force all your users to change their passwords because the temporary password is a security risk

#!/bin/sh
for i in `more userlist.txt `
do
echo $i
echo $i | change -d 0 "$i"
echo; echo "User $i will be forced to change password on next login!"
done

I then log as that user and see this

WARNING: Your password has expired.
You must change your password now and login again!
Changing password for user amcorona.
Changing password for amcorona
(current) UNIX password: