How to use parallel ssh (PSSH) for executing ssh in parallel on a number of Linux/Unix/BSD servers

Posted on in Categories Cloud Computing, Command Line Hacks, Howto last updated April 21, 2017

Recently I come across a nice little nifty tool called pssh to run a single command on multiple Linux / UNIX / BSD servers. You can easily increase your productivy with this SSH tool.

More about pssh

pssh is a command line tool for executing ssh in parallel on some hosts. It provides specialties includes:

  1. Sending input to all of the processes
  2. Inputting a password to ssh
  3. Saving output to files
  4. IT/sysadmin taks automation such as patching servers
  5. Timing out and more

Let us see how to install and use pssh on Linux and Unix-like system.

pssh-welcome

PSA: Intel Atom C2000 Chips Flaw Bricking Routers/NAS/Firewall devices that are powered by Linux, pfSense and FreeNAS

Posted on in Categories Hardware last updated February 7, 2017

Intel’s Atom C2000 chips are bricking products, and it’s not just Cisco hit. From the theregister:

Intel’s Atom C2000 processor family has a fault that effectively bricks devices, costing the company a significant amount of money to correct. But the semiconductor giant won’t disclose precisely how many chips are affected nor which products are at risk. Coincidentally, Cisco last week issued an advisory warning that several of its routing, optical networking, security and switch products sold prior to November 16, 2016 contain a faulty clock component that is likely to fail at an accelerated rate after 18 months of operation.

Intel has “Silvermont” which is a microarchitecture for low-power Atom, Celeron and Pentium branded processors used in systems on a chip (SoCs) made by Intel. It includes:

  1. Avoton – SoCs for micro-servers and storage devices.
  2. Rangeley – SoCs targeting network and communication infrastructure.

9 Awesome Open Source Web Performance Software For Linux and Unix-like Systems

Posted on in Categories Open Source last updated February 4, 2017

Web performance is nothing but the speed in which web pages are downloaded and displayed on the user’s web browser. Faster website speeds have been shown to increase sales or increase visitor loyalty including user satisfaction. Particularly useful for those use slow internet connections or on mobile phones/tablets. You can increase the speed of page load using:

  1. Server side cache
  2. Browser side cache
  3. Faster disks
  4. Image optimization
  5. Web application accelerator focusing on optimizing caching and compression
  6. Load balancing and SSL offloading
  7. Geo or DNS-based load balancing and more.

In short, one can increase the time it takes for pages to render using multi-layered cache and asynchronous communication with server-side components. In this post, I will list my favorite open source software based TCP/HTTP load balancer and proxying solution for web performance.

7 Awesome Open Source Analytics Software For Linux and Unix-like Systems

Posted on in Categories Open Source last updated January 16, 2017

Web analytics is nothing but the measuring web traffic. It is not limited to measuring web traffic. It includes:

  1. Analysis
  2. Data collection
  3. Reporting of web data for purposes of understanding and optimizing web pages

Google Analytics is the most widely used cloud-based web analytics service. However, your data is locked into Google Eco-system. If you want 100% data ownership, try the following open source web analytics software to get information about the number of visitors to your website and the number of page views. The information is useful for market research and understanding popularity trends on your website.

Book Review: PAM Mastery

Posted on in Categories Reviews last updated November 1, 2016

PAM Mastery Book ReviewLinux, FreeBSD, and Unix-like systems are multi-user and need some way of authenticating individual users. Back in the old days, this was done in different ways. You need to change each Unix application to use different authentication scheme. Also, authentication schemes differed between a variant of Unix systems. Porting was a nightmare. For example to use Windows Server (Active Directory) or LDAP for authentication you need to make changes to an application. Each application had its way of authenticating users. So Open Group lead to the development of PAM for the Unix-like system. Today Linux, FreeBSD, MacOS X and many other Unix-like systems are configured to use a centralized authentication mechanism called Pluggable Authentication Modules (PAM). The book “PAM Mastery” deals with the black magic of PAM.

Disabling Google Chrome PDF viewer

Posted on in Categories Howto last updated August 29, 2016

Google Chrome has “Chrome PDF Viewer” to view or open pdf files. It is an unwanted feature. I do not need it at all. I want my PDF open in Preview on a MacOS X or default pdf viewer in Linux. This feature was hidden. I want to disable it from my Google Chrome browser because it was slow scrolling with a large pdf file sizes.

Accessing Internet from cloud VM when you have only private network enabled

Posted on in Categories Hardware, Howto last updated August 17, 2016

We have a couple of virtual servers hosted with Softlayer for processing data and backup purpose. The public interface is completely turned off i.e. no Internet access. We can only access VMs using a VPN. It resulted in decreased costs and many security problems for backend servers. However, when you order “Private Network Only” cloud VM, you cannot route outgoing traffic to the Internet using your VM.

Book Review: Tarsnap Mastery Online Backup For the Truly Paranoid

Posted on in Categories Amazon Web Services, Cloud Computing, Reviews last updated January 4, 2016

Tarsnap Mastery: Online Backups for the Truly Paranoid (IT Mastery) It’s always a good idea to keep backups of all of your data in multiple places. Every Linux or Unix sysadmin must master the art of backups if you want to keep your data forever. Most sysadmin recommend and follows the 3-2-1 rule:

  1. At least three copies of data.
  2. In two different formats.
  3. With one of those copies off-site.

Tarsnap is one of such off-site backup sites. It’s a secure online backup system for UNIX-like system. This service encrypts and stores data in Amazon S3. To use Tarsnap perfectly and feel secure about your backups, you need the “Tarsnap Mastery” book by Michael W. Lucas. It is no secret that I’m a big fan of his book series. Let’s see what the book is all about.

Book Review: FreeBSD Mastery – ZFS

Posted on in Categories Datacenter, Reviews, Storage last updated October 26, 2015

FreeBSD ZFS BookOnce again a great FreeBSD book to read. I was anxious to read this after reading FreeBSD Mastery- Storage Essentials 2014. I read where he was writing a ZFS book, but didn’t know it was out until I was asked to review it. I loved the introduction, being into hardware and history, it was such great knowledge. I knew some of this information prior, no where near as in depth as these authors covered. The style is so easy to read and mentally kind, it’s always a pleasure to read. Of course ZFS has been used in other Oses (such as Solaris and Linux) and while it is not new to FreeBSD, many people are either afraid of it because they are moving from Linux or they have heard negative things about it.

Book Review: FreeBSD Mastery – Storage Essentials

Posted on in Categories Open Source, Reviews, Storage last updated October 26, 2015

FreeBSD Mastery: Storage EssentialsI have been a big fan of author, Michael W Lucus for years now. I love his Absolute OpenBSD book and have yet to read one better on OpenBSD. I am also a fan of his book Absolute FreeBSD so was looking forward to reading this. I had high expectations but at the same time really didn’t know what to expect other than I knew I would be able to understand it. I love him as a writer because he truly recognizes the beauty of BSD. His passion for it shows in his writing. I feel like I am the only one with these feelings and then I read one of his books and know I am not alone with this passion for an operating system. His style of writing is always pleasant and I always learn.

For me, I use FreeBSD for a number of reasons. Its stability is a big benefit to those of us who use it for work or at home. It also lets me set it up the way I want it. With FreeBSD if something crashes I have the possibility to understand why it is crashing and how I am going to handle it. If I am lost on how to handle it, this book is a great reference in dealing with disk solutions.