Automatic loading of SSH keys from scripts

a keyWhen using SSH with public-key authentication, ‘ssh-agent‘ is a useful compromise between storing the SSH private key un-encrypted to disk and having to type the key`s passphrase every time you need to make an SSH connection.

When using SSH from scripts, things are further complicated, because no one is around to type in the passphrase. From this reason, SSH keys that are used by servers are, more often then not, stored with no encryption, thereby becoming a lucrative target for hackers.

With some clever manipulation, a script can be written in such a way where it can make use of the ‘ssh-agent‘ to load and use an encrypted private key.

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Linux ports of games not offered via the Humble Store. How strange.

The humble bundle and a sad Linux penguinOne of the reasons I am a fan of the Humble Bundle and a repeat buyer, is the fact that it always offers Linux ports of the games sold.

With that in mind, Imagine my surprise, when I found out that games that were already sold in the past via the bundle, do not offer the Linux ports when they are sold via the Humble Store.

Case to the point: Limbo. I have the Linux port. I bought it via the Bundle. But I can’t recommend it to my Linux using friends because they have no way to get it now that the bundle is done with.

New approaches to terminal emulator applications

Terminal Emulator IconThe terminal emulator is an ancient but essential tool in the arsenal of any advanced computer user. The terminal emulator allows one to access the command line shell interface of the operating system while working in a graphical environment. The existence of the terminal emulator allows one to simultaneously enjoy both the visual appeal and discoverability of graphical desktop applications and the accurate efficiency and expressiveness of a command-line interface.

While the graphical computing environments have been undergoing a user-experience driven revolution in recent years, the terminals emulators have seen little change. There have been some superficial additions such as tabs and split windows, but in essence today’s terminal emulators still closely resemble their hardware counterparts of old.

Recently there have been attempts to bring modern UI concepts to the terminal emulator and give it a modern overhaul.

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Syncthing a Free Software peer-to-peer file sync software

Syncthing logoSo-called cloud storage services such as DropBox, SpiderOak, SkyDrive and Google Drive provide a convenient means of moving files between different computers and have largely eliminated the need to use USB thumb drives or other physical means to move data. Most online services however, suffer from one or more of the following shortcomings:

  1. The amount of storage one can use tends to be very small. Especially when considered against the size of an average computer hard drive.
  2. The user’s data is completely exposed to the cloud provider.
  3. The end-user software provided by the cloud provider may not support all platforms the user has, and may provide limited features.

From the above reasons, I was very excited to hear about BitTorrent Sync. BitTorrent Sync eliminates the first problem by having the amount of storage a user can use limited only by the size of the hard drive that he has. It solves the second problem by being completely peer-to-peer, which means that data is synced only between computes that the user chooses and controls. The 3rd problem is so far been approached in a satisfactory manner as clients are available for all major platforms.

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About Docker and Storage

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.

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Building Ethernet-over-IP tunnels with Linux

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 Open 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).

Creating Gantt-Charts on Linux

Like many unfortunate office/productivity areas, project management, and especially Gantt-Chart production, seems to lean heavily on a single Microsoft product to the point where abstract-seeming work practices are actually derived from technical features and properties of that product.

A couple of years ago I tried to create a Gnatt-Chart on Ubuntu. I initially thought that would be a no-brainer, but it proved to be harder then anticipated.

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