Using a Yubikey for 2-factor authentication

For those of you who have not yet encountered a Yubikey, it is a physically small security key which empowers passwordless or 2-factor authentication in a number of different scenarios. They now support a huge number of protocols including One Time Passwords, NFC, FIDO2, U2F, Smart card, and OpenPGP.

Mine has been living on my keyring for several years now, and has proved invaluable for me accessing both my physical and electronic world.

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Importing missing apt keys

This is another one where I get a mental blank.  I know there is a way to import a new gpg key for apt, but I always have to look it up.

sudo apt-key adv --keyserver --recv 886DDD89

And that is all there is to it.  (Substitute your favourite keyserver and the correct key, obviously).

Ipsec on a small LAN

Most tutorials cover implementing IPsec as a VPN solution between two sites, but what if you want to secure communications on one site representing a not atypical home LAN with a couple of machines: some wireless, some Linux, some Android, some Windows, and a dual ipv6/ipv4 stack (courtesy of Hurricane Electric’s free TunnelBroker service)?  And to make life more difficult, there are some devices that don’t support IPsec at all.  Obviously, you need at least two IPsec capable machines for this to make much sense.

Does it work, and how well?

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Tethered shooting with gphoto2

Tethered shooting with a DSLR (shooting directly to a connected computer via a USB cable) on Linux is very, very easy, assuming you have gphoto installed.

gphoto2 --capture-tethered

And start shooting away!  However, I wanted to be a bit cleverer and improve my workflow slighty to overcome a few shortcomings.  I wanted to:

  1. Shoot raw
  2. Display the last shot full-screen.
  3. Not clobber existing files if I re-ran the tether.

it turns out that this is all easy to do with a small bash script and gphoto’s “hook” capabilities.  I knocked up the following based upon the sample distributed with gphoto and called it

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GIMP xcf file size reduction

If you are a GIMP user you can end up with plenty of .xcf files.  I do all my editing with xcfs after importing from RAW with the excellent ufraw-gimp plugin.  But they can get pretty big…

Step forward bzip2.  If you are running linux, you will already have bzip installed, and the bonus is that GIMP can read and write natively its xcf files compressed with bzip.  There is a small performance hit on opening and saving files, but you can save 10-40% of file-size; that can easily be 40 MiB for a simple file with a couple of layers.

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