Monthly Archives: February 2016

Difference between jboss and tomcat application servers

There has been lot of posts and questions about where to use jboss and where to use tomcat.

Tomcat is just a servlet container providing servlet capabilities whereas jboss provides you a complete JEE stack. Few features of JEE stack are as below :-

  • JMS messaging for asynchronous integration
  • Web Services engine (JAX-WS and/or JAX-RS)
  • Management capabilities like JMX and a scripted administration interface
  • Advanced security, e.g. out-of-the-box integration with 3rd party directories
  • EAR file instead of “only” WAR file support
  • It also has EJB (enterprise java beans)

This definitely makes jboss more resource consuming as compared to tomcat. To know how to install and run jboss on linux please see the below link :-

https://docs.jboss.org/jbossas/jboss4guide/r1/html/ch01.html

For installing tomcat on linux please go through the http://tecadmin.net/steps-to-install-tomcat-server-on-centos-rhel/# or https://www.mulesoft.com/tcat/tomcat-on-linux-installation-and-configuration.

Feel free for any queries or comments.

-Alok Thaker

 

Creating your own wifi hotspot with chillispot,freeradius & daloradius with mysql

You are at airport and you connect to hotspot, you are required to give a password send to your mobile device and use internet for an hour or a limited time period. This made me think what is the concept which makes this system so secured and feasible. Its just add an extra layer of security to your wifi hotspot with a time interval.

How is this possible ?

The answer is through chillispot which is an open source captive portal for giving you web based login to access your wifi hotspot considering it as your wifi point access controller. but for AAA(authentication,authorization and accounting) you have to use freeradius which can be integrated with chillispot to give more flexiblity to all the AAA.

For chillispot you can find more details on http://www.chillispot.org/ and for freeradius on http://freeradius.org/.

To handle freeradius with GUI you can use daloradius to manage the users, time intervals etc.  You can find more details on http://www.daloradius.com/.

To configure chillispot with freeradius with mysql and daloradius please go through the link http://alessandrodistefano.eu/debian-wifi-hotspot-with-coovachilli-freeradius-mysql-and-daloradius/ which gives you all the exact details you need.

If you don’t want to work so hard with all the installations of the individual component you can use easyspot. For more details http://easyhotspot.inov.asia/index.php/documentation.

Feel free for any queries or comments.

-Alok Thaker

Why CDN ?

CDN known as Content Delivery Network  or content distribution network generally consist of distributed servers to server web contents,assets from different geographical locations as per the origins of the request.

CDN can store web pages, content, media streaming files, dynamic content and it helps in performance optimization and faster browsing of websites.  You can create CDN with various cloud providers like Amazon and one of the biggest one is Akamai.

To get started with CDN with Amazon you can use cloudfront service and for more details go through http://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/GettingStarted.html & for akamai you can register and follow more details on https://www.akamai.com/us/en/cdn.jsp.

Generally CDN helps in faster response and performance boost for your portal but it has it’s own limitations like for using CDN you have to ensure you have a internet up and running along with failure of CDN host can make your website unusable too.

Though apart from few limitations the advantages it holds are enormous and various big providers are using CDN extensively.

Feel free for any comment or queries.

-Alok Thaker

 

 

Running a Linux virtual machine in Azure Cloud

Microsoft Azure cloud raised eyebrows giving $12100 credits to use their services on sign up with your credit card details. No doubt Microsoft Azure Cloud is no different in the use case like Amazon Web Services it infact has been good in GUI inclusive of good look & feel approach towards creating a new vm giving you MSDN subscription too.

Once you register with your credit card details and sign into preview portal with your hotmail account. Then Click on  On the Hub menu, click New > Compute > Ubuntu Server 14.04 LTS.

  • On the Create virtual machine blade, click Basics. Enter a Name you want for the VM, and a public key file (in ssh-rsa format, in this case from the ~/.ssh/id_rsa.pub file). If you have more than one subscription, specify the one for the new VM, as well as a new or existing Resource group and an Azure datacenter Location.
  • Click Size and select an appropriate VM size for your needs. Each size specifies the number of compute cores, memory, and other features, such as support for Premium Storage, which will affect the price. Azure recommends certain sizes automatically depending on the image you choose
  • Click Settings to see storage and networking settings for the new VM. For a first VM you can generally accept the default settings. If you selected a VM size that supports it, you can try out Premium Storage by selecting Premium (SSD) under Disk type.
  • Click Summary to review your configuration choices. When you’re done reviewing or updating the settings, click OK.
  • While Azure creates the VM, you can track the progress in Notifications, in the Hub menu. After Azure creates the VM, you’ll see it on your Startboard unless you cleared Pin to Startboard in the Create virtual machine blade.

This would create virtual machine with your Linux Ubuntu Server 14.04 LTS  Image. You can connect to Azure VM ubuntu machine with the ssh key.

For more in depth details you can go through Azure Documentation on https://azure.microsoft.com/en-in/documentation/articles/virtual-machines-linux-tutorial-portal-rm/.

Feel free to comment or any queries.

-Alok Thaker

 

 

Brainstorming Linux Interview Questions

Lot of people and candidates are moving towards career on Linux system administration and network. A good linux sys admin also needs to have a sharp logical and troubleshooting skills along with blend of a hold of shell scripts,python programming.  I have made list of few questionnaires which can make a candidate berserk or to make them think twice before answering :)

Here are those :-

  1. What is sticky bit in Linux and how do you set or unset it ?
  2. What is LVM ? How can you expand,reduce,resize your LVM ? How can you recover your LVM if got corrupted ?
  3. Permissions in Linux. What is Umask etc ?
  4. What are system calls ?
  5. Difference between ext2,ext3 & ext4 filesystems ?
  6. Do you need swap compulsory ?
  7.  What is IPV6 and IPV4 ? How can you set IPV6 ip addresses in Linux ?
  8. DHCP Server-Client Configuration.
  9. Iscsi how to configure the targets and clients ?
  10. OS Hardening.
  11. How do you secure your web servers, application servers, database servers ?
  12. Multi-node, 2 node Clustering & Load balancing experience and implementation.
  13. RAID Configuration.
  14. Multipathing
  15. XEN,KVM, Virtualization experience.
  16. Kernel compilation,installing/removing modules etc.
  17. Shell script basics to monitor with ping, wget,curl,reporting etc.
  18. Nagios ,OpenNMS,Zabbix and other monitoring systems.
  19. Mail Servers Implementation with Zimbra,Postfix,Dovecot,Sendmail etc.
  20. SSL Configuration & implementation for web servers.
  21. Database Replication
  22. Performance Optimization of the web Servers.
  23. Web server implementation using apache,nginx etc.
  24. Troubleshooting & debugging using firebug, yslow etc.
  25. Router handling and L3 switches management.
  26. Experience in offshore support handling various clients abroad.

In addition to this you should have a good communication and writing skills because that really helps you to connect with the interviewer. Be confident and hardest worker in the room. You might not know everything but whatever you know that should be made understood and in a very clear & satisfactory way.

Feel free to ask any queries or comments.

-Alok Thaker

 

 

Amazing Desktop Effects in Linux

While working on Linux various users complain that we don’t have much of the effects we can use in linux desktop environments. There has been various desktop managers like GNOME,KDE,XFCE,Enlightment etc which might have great features but not much to do with cool desktop effects.

There is a package called compiz fusion which is an extension of compiz which is a kind of window manager which provides Destkop cube to be  with 3D effects and other plugins and themes for making your linux desktop really cool.

Ubuntu having unity desktop environemnt is also a part of compiz and can be customized to your needs.

For more details on Compuz Fusion please check more on http://www.compiz.org/.

Feel for any comments or queries.

-Alok Thaker

In vehicle Infotainment systems

Everyone wants to own a car or already has it. There has been lot of buzz around IVI (In Vehicle Infotainment systems) where you have a complete automation of the media player, bluetooth synch, parking system, reverse & side views camera etc.

It has been major criteria for Car manufacturing companies to provide as much facilities on touch of your finger. It is that time we have IVI systems in place and yes you guess them right there are various linux flavours used for it.

Montavista linux which is a commercially driven linux OS which provides you lot of capabilities in automation systems. There is an open source solid alternatives for automative infotainment systems name AGL i.e Automative Grade Linux. You can find various details of it’s configuration,implementation and usage on https://www.automotivelinux.org .

There has been other innovative projects like Tizen which has SDK and considered to be a great OS for mobile devices, wearable devices and In Vehicle infotainment systems.  More details https://www.tizen.org/ .

Feel free for any comments or any queries.

-Alok Thaker

 

NOSQL and RDBMS which one to go for ?

There has been lot of hype around NOSQL which stands for not only sql making it quite different from RDBMS terminology of maintaining relations between tables,records,fields and entities. RDBMS such as mysql,Oracle,MariaDB have been great choices for various environments but when we talk about distributed systems and horizontal scalability they are not the preffered choices as RDBMS demands good hardware and maintenance as compared to NOSQL.

Google,Yahoo are using distributed file systems where there preferred choice is NOSQL because it is horizontal scalability feature of adding nodes and reducing the load on CPU and also perform better in distributed file systems as compared to vertical scalability of increasing CPU,Memory etc in RDBMS. Various NOSQL databases are MongoDB, ApacheCouchDB, Redis, Neo4j etc which are being used a lot now a days.

I have been fan of MongoDB and for more details regarding installation you can check on https://www.mongodb.org/downloads and for CouchDB go through http://couchdb.apache.org/.

Feel free to comment or any queries.

-Alok Thaker

What is parallel virtualization and hardware virtualization ?

Virtualization has picked up immensely where you have private and public clouds being build up everyday helping you to save your cost by saving your on premise cost and administration.

The major difference between pvm and hvm is that hardware virtual machine takes advantage of cpu extensions like VT-x/AMD-V features also network,storage, memory but in case of pvm it uses mostly the kernel to perform the virtualization.

In cloud service providers like Amazon,Rackspace you find some machines with hvm and very few with pvm alternatives because hvm performs really better making use of CPU extensions of virtualization instead of parallel virtual machines who are totally dependent on the software and a kind of run-time environment and library for message-passing, task and resource management, and fault notification.

You have KVM’s too which stands for kernel virtual machines where kernel provides full virtualization supporting x86 hardware.

For more details you can always search and there many sites mentioning the peformance benchmark of pvm and kvm’s.

Feel free to comment or queries.

-Alok Thaker

 

Developing games,animation,movies using opensource

There has been curiosity within me that I should be able to create some games of my own,animation,short movies without coding because coding requires lot of hard work and time. It’s now easy to create 2D-3D animation,creating games and movies easily by drag and drop too.

There are various new open source software’s available for Linux,Windows,MAC etc to create games,animations like one of the most famous is scratch project which is developed for kids aging 8 to 16 years for utilizing their creative minds for developing games and animations. Though it is for children between 8 to 16 it has gain rapid popularity among all age groups. Just install Scratch and start using it. More details for the Scratch can be found on https://scratch.mit.edu.

Other softwares which has impressed me are Stencyl, Pencil,Tupi and one of the best is Synfig Studio for advanced 2D animation and drawing program.  You can also create a movie using still images using ffmpeg. I would take another post dedicated to ffmpeg which would have more details of it’s usage soon.

For 3D modelling and rendering there are various softwares like Blender, Ayam,Art of Illusion,K-3D,MakeHuman being few of the famous ones.

Feel free to comment or any queries.

-Alok Thaker