Ifblog (ponderings 2.0)

Sunday, May 18, 2014

About Docker and Storage

Filed under: Home Cloud, Linux, RHEL, Sysadmin — ifireball @ 23:09

Docker LogoDocker seems to be all the rage this days, everyone seems to be running around integrating it, building things on top of it and generally giving it great press. It is no surprise then that I decided I should look into what this is all about.

The one bit of information I found somewhat less frequently discussed is where everything gets stored.

Storage is important. Disk partitioning is the first task any OS installer puts you through, even before that, an experienced sysadmin pays great attention to what kind of storage devices and channels go into a server. Data storage decisions have great effect on how your system end up performing, how robust is it as well how easy is it to backup and repair when it breaks. Bad storage decisions tend to be hard to fix, necessitating large data transfers and long downtimes. Indeed, allowing a sysadmin to fix bad storage decisions is where LVM, Veritas Volume Manager and other storage visualization tools come from.


Saturday, May 17, 2014

Building Ethernet-over-IP tunnels with Linux

Filed under: Linux, Sysadmin — ifireball @ 13:24

TunnelThere is a not so well documented way to link together separate Ethernet segments by using GRE tunnels over IP networks while using only Linux Kernel capabilities and not requiring any userland daemons.

This can be useful to make physically separate networks appear as one, although linking over the internet in this way may not be very wise as the tunnel isn’t encrypted.

This can also be used to simulate multiple separate networks for virtual machines running on different physical hosts, without requiring VLAN tagging support from the physical network or using Opem vSwitch.

The basic idea is to add a tunnel link of type “gretap” and attach it to a bridge, here is how to see what little documentation is available about it:

ip link add foo type gretap help

Here is a blog post providing some further explanation.

This capability has existed in the kernel since 2.6.29, so it is included in most moderately-recent distributions including RHEL/CentOS 6, Ubuntu (since 9.10 – Kermic) and Debian (since 6.0 – Squeeze).


Friday, May 16, 2014

Remote-controling Linux from any mobile device

Filed under: Coding, Free Software, Security, Ubuntu — ifireball @ 20:12

Remote ControlsRemote-controlling desktop computers from mobile devices is an idea that is typically implemented in the form of an Android/Iphone app that connects to the controlled computer over SSH, VNC, RDP or some proprietary protocol typically requiring a closed-source server component.

It had occurred to me a while ago that it shouldn’t be too difficult to write a webapp that would turn any mobile device with a web browser into a remote control for the server its running on, and I was wondering why I didn’t see any implementations of that idea around.

Well now there is one such implementation in the form of “Linux Remote Control“.


Installing Windows from Linux

Filed under: Evil Plans, Home Cloud, Sysadmin — ifireball @ 19:04

It can be done.

But its more work then simply Kickstarting or Preseeding a Linux distro.

Here is an article on how to do it, its a part of a rather interesting distro called “Ultimate Deployment Appliance” that is a virtual appliance that can be setup to deploy many different OSes over the network.

Here is another article from the documentation of “RIS for Linux”, a software package needed for performing the installation.


Friday, December 6, 2013

News Digest

Filed under: Coding, Security, Sysadmin — ifireball @ 18:10

List of things I find interesting and think people should know about:

  • Caylon is a new programming language from RedHat that is meant for large system development and can run on both the Java virtual machine (JVM) and web browsers’ JavaScript engine. This makes it useful for programming both the client and server-side components of modern applications.
  • Bad Bios is the nickname given by Dragos Ruiu, an apparently well-known security researcher to a new type of malware found in the wild that seems to be able to infect computer BIOS components directly and then escalate the attack in infect all popular operating systems, Linux-based ones included. Not stopping there, it also seems this malware is capable of communicating with an infected computer even when all its communication components have been disconnected. It seems to do this by utilizing high-frequency sound-waves. This technique of using sound to facilitate communications with otherwise disconnected computers was also explored by scientists from Germany.
  • InfiniSQL seems to be one man’s projects to produce a very scalable multi-node database. It seems to be network-protocol-compatible with PostgreSQL and may have an interesting future.
  • Webminstats is a server performance statistics collection plug-in for Webmin. Used together those tools can provide a useful monitoring and management solution (although not very pleasant looking, though that can be somewhat  remedied) for small to medium sized networks.
  • ExplainShell is a new web-based tool for  breaking down complex Linux shell commands and explaining their components. It was recently open-sourced and seems to have a good potential of becoming a very useful tool for people trying to learn Linux shell usage and scripting. The developer was even kind enough to include a readme file listing instruction on how to run your own copy of the website.

Friday, September 6, 2013

The Android’s Dream sounds like another Scalzi masterpiece

Filed under: Reading, SciFy — ifireball @ 13:14

The Androind Dream by John ScalziI really wish I had the patience and time time to read, I haven’t quite managed to go through a full book in quite a few years now.

But that shouldn’t stop anyone else, go watch mark’s video and read his review (In that order!) and buy Scalzi’s book!

Saturday, August 31, 2013

I joind the PRSM social network

Filed under: EFF, Free Software, Security — ifireball @ 11:50

Please come and join too, its awesome.

On the Phenomenon of Bullshit Jobs

Filed under: Sysadmin — ifireball @ 11:44

This article already made the rounds a couple of weeks ago, but I find myself compelled to post a link here since it seems so relevant to everyone I know.

As I think of this, it doesn’t seem to me that that are that many jobs that are 100% bullshit, I think all jobs have necessary components to them, but it does seem that the amount of time spent performing “bullshit tasks” in a given job keeps expanding.

I think I may be lucky, I do get to spend a considerable amount of time solving technical problems for my clients, but it seems I spend an equal, if not larger portion of my time attending meetings, writing and obtaining approval for documents and procedures, scheduling and coordinating. It also seems that new automation tools and techniques go a long way towards shrinking the time spend performing  the former set of tasks while contributing nothing to the efficiency of performing the latter.

Saturday, August 10, 2013

Quick list of open-source webmail clients

Filed under: Free Software, Sysadmin — ifireball @ 16:19

Cory Doctorow recently wrote about Mailpile, an Indiegogo-based effort to fund development of a new open-source web-based E-Mail client.

I really have to wonder, does the world really need another such client? Here is a bunch of them:

  • Roundcube – Written in PHP with a moderm AJAX UI.
  • The Horde Project – Not only provides E-Mail, but a full groupware suit.
  • Zimbra – Not only provides a client but also a full server that can replace Microsoft Excange.
  • SquirrlMail – Includes a rather old style UI, but seems to be very popular. Most web hosting providers support installing it directly with their site management tools.
  • Mailr – Not very pretty, but written with Ruby On Rails, if you don’t want to run PHP.
  • And many, manymore.

I’ve been running my own mail sever for years. In my view, that is where the bigger  problems are, the constant flood of spam and other E-Mail attacks, seems to have led most internet service providers to block all E-Mail sent from anyone who doesn’t look like a large service provider. When running my own server I’d often find out that my mail get rejected unless I relay it through such a provider.

Ways to self-host your own website

Filed under: Free Software, IndieWeb, Sysadmin — ifireball @ 15:35

It seems that recent news have triggered a wave of distrust in cloud and hosted web service. The popularity of hosting your website on your own computer seems to be growing. Personally, I’ve been running my own mail server for years, but several concerns have prevented me from trying to host my own website:

  1. Asymmetric bandwidth – The existing broadband infrastructure was laid by large a powerful communications companies that are more interested in broadcasting video and other media to passive “consumers” then in allowing “users” to communicated. A typical 100Mbit broadband cable connection tends to provide only mere 1 or 2Mbit of upload bandwidth.
  2. Security – Hosting a website from your own internal network typically means potentially exposing your network directly to outside threats.
  3. Availability – If anything happens to your home network – it happens to your website. Power failures, computer crashes, bandwidth-eating games and peer-to-peer software, they will all affect your site.
  4. You are on your own – Support services can be very useful when your tile is limited. There is no one to turn to we you do your own hosting.

Having considered the above, recent disappointment with a hosting service I use, had led me to consider self-hosting once more, hare are some ways one can accomplish that:


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