Installing Firefox via Snap is an easy way to get the latest Firefox version on your favorite distro, regardless of the version the distro ships with. However, due to Snap’s security model, Yubikeys, or any other FIDO tokens do not work out of the box. To enable U2F devices, like Yubikeys, you need to give the Firefox package the necessary permissions manually:
$ snap connect firefox:u2f-devices
A quick and secure way to generate numerical PINs. The only dependency is coreutils so it should work on almost any system out-of-the-box.
$ shuf --random-source=/dev/urandom -i 0-9 -r -n 6 | paste -sd ''
659010
The following snippet should work on every system that has coreutils.
$ shuf /usr/share/dict/words --repeat --random-source /dev/random -n 5
You can swap /usr/share/dict/words with any good wordlist, like EFF’s or Arnold Reinhold’s Diceware list.
You can also add it for ease of use to your ~/.bash_aliases
alias passphrase="shuf ~/dotfiles/misc/diceware8k.txt --repeat --random-source /dev/random -n"
And then you could easily use it in bash:
$ passphrase 5
notch
kane
to
drag
cater
WP-Syntax was a great syntax-highlighting plugin for WordPress. However, development had ceased and it was not updated for a very long time. While it is not broken per se, it didn’t work with Jetpack’s markdown support and so I stopped using it on the site and started using a different plugin. With the introduction of the Gutenberg editor, I started looking again for a plugin that will allow me to easily highlight fenced code blocks (this feature worked in the old editor with SyntaxHighlighter Evolved but isn’t supported in Gutenberg). Realizing that I don’t want three syntax-highlighting plugins enabled simultaneously, and not wanting to have an abandoned plugin enabled, I decided to migrate all the posts from WP-Syntax to a new solution.
The new solution I chose was PrismJS. I decided to use it directly (without a plugin) as it highlights by default all the <pre><code class="language-..."> constructs (which is what markdown produces as well) and I didn’t want (yet again) to use plugin specific shortcodes like before which will require migration when the plugin eventually stops working.
WP-Syntax used <pre lang="...">code goes here</pre> construct. Furthermore, it took care of html escaping everything inside the <pre> tag. So the migration solution would be to rewrite the <pre> tags to <pre><code> constructs, html escape the code inside the pre tag and finally remove any leading newlines. I wrote it to work on dumped SQL tables as it seemed easiest. The flow is
$ mysqldump --add-drop-table -u USER -p blog wp_comments > wp_posts.sql
$ python3 < wp_posts.sql > wp_posts_updated.sql
$ mysql --user=USER --password blog < /tmp/wp_posts_updated.sql
#!/usr/bin/python3
import re
import html
import sys
def convert(fin, fout):
for line in fin:
# Each post is in a single line
# <pre><code> doesn't ignore the first newline like <pre>
replaced = re.sub(r'<pre lang=\\"(.*?)\\">(?:\\r)?(?:\\n)?(.*?)</pre>', replace_and_escape, line)
print(replaced)
if line != replaced:
print(line, replaced, sep="\n============>\n", file=sys.stderr)
def replace_and_escape(matchobj):
language = matchobj.group(1)
# We don't escape quotes because it's unnecessary and it would mess up the
# SQL escaping
content = html.escape(matchobj.group(2), quote=False)
return r'<pre><code class=\"language-{}\">{}</code></pre>'.format(language, content)
if __name__=='__main__':
convert(sys.stdin, sys.stdout)
By default, when you touch a Yubikey it types an OTP code. These codes looks like:
cccjgjgkhcbbirdrfdnlnghhfgrtnnlgedjlftrbdeut
Theoretically they are used for Yubico’s proprietry authentication, but in reality they are mostly annoying. This is especially true for Yubikey Nano, which is impossible to remove without touching it and triggering the OTP.
Disabling the OTP is possible using the Yubikey Manager, and does not affect any other functionality of the Yubikey.
$ sudo apt install yubikey-manager
$ ykman config usb --disable otp
Disable OTP.
Configure USB interface? [y/N]: y
Note for Yubikey 4: the above command will not work and fail withe the following error:
Error: Configuring applications is not supported on this YubiKey. Use the `mode` command to configure USB interfaces.
Instead use the following command:
$ ykman mode FIDO+CCID
Set mode of YubiKey to FIDO+CCID? [y/N]: y
Mode set! You must remove and re-insert your YubiKey for this change to take effect.
Virtual Machine Manager (virt-manager) doesn’t automatically start your virtual networks. This leads to the following error when starting a vitual machine
Error starting domain: Requested operation is not valid: network 'default' is not active
To solve this error, on Virtual Machine Manger go to Edit->Connection Details->Virtual Networks, select the required network (‘default’ in our case) and press the Start Network button (has a play-button icon). You can avoid having to go through this process by ticking the Autostart checkbox, which will make the network start automatically at boot.
Google Photos imposes a 100 megapixel limit on uploaded photos. This may sound like a lot, as even the very high-end Sony Alpha a7R III has “only” 48MP sensor, but in reality when you shoot panoramas and stitch them yourself, you can quickly get there, and hit the 100MP limit. When you try to upload your huge panorama to Google Photos, you will get a
A photo or video was skipped
error.
To solve it, you need to resize your image and make it smaller. This can be done automatically using ImageMagick’s convert:
$ convert -resize "100000000@>" panorama-in.jpg panorama-out.jpgThis will resize the panorama-in.jpg to at most 100MB, and save it as panorama-out.jpg. The > makes sure we will only down-size larger photos.
By default under Debian, ImageMagick comes with a very strict `policy.xml` controling the resources it can use. Practically, it means that unless you change those limits, you’ll encounter resource limit errors such as:
convert-im6.q16: width or height exceeds limit `panorama-in.jpg' @ error/cache.c/OpenPixelCache/3802.To solve it you will need to edit /etc/ImageMagick-6/policy.xml and increase the limit for memory, width, height and area. For example:
<policy domain="resource" name="memory" value="8GiB"/>
<policy domain="resource" name="width" value="128KB"/>
<policy domain="resource" name="height" value="128KB"/>
<policy domain="resource" name="area" value="8GB"/>
I’ve made available in my personal repository amd64 builds of Hugin 2018.0.0 for Debian Stretch.
Enjoy!
After a recent upgrade to Debian Stretch, my OpenVPN server stopped working. Checking the relevant log file, /var/log/openvpn.log, I found the following not very helpful error message.
Fri Nov 23 16:46:37 2018 OpenVPN 2.4.0 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [LZ4] [EPOLL] [PKCS11] [MH/PKTINFO] [AEAD] built on Jul 18 2017 Fri Nov 23 16:46:37 2018 library versions: OpenSSL 1.0.2l 25 May 2017, LZO 2.08 Fri Nov 23 16:46:37 2018 daemon() failed or unsupported: Resource temporarily unavailable (errno=11) Fri Nov 23 16:46:37 2018 Exiting due to fatal error
Fortunately, someone already reported this error to debian and found out that the error is caused by the
LimitNPROC=10
in the /lib/systemd/system/openvpn@.service. The LimintNPROC directive in systemd is used to limit the number of forks a service is allowed to make. Removing this limit, might not be the best idea. So, I would suggest that instead of commenting it out, to find out the minimal value that allows OpenVPN to start and work. After some testing, I found that the minimal value that worked for me is
LimitNPROC=27
After editing the /lib/systemd/system/openvpn@.service, you need to reload the systemd service files and restart the OpenVPN server process.
$ sudo systemctl daemon-reload $ sudo systemctl restart openvpn@server
There are three things that need to be updated in Debian Stretch in order to get the Radeon RX 550 running properly (or at all): kernel, mesa and proprietary binary firmware (bummer, I know).
First thing, make sure you have stretch-backports in your apt-sources with all the relevant components.
$ deb http://ftp.debian.org/debian stretch-backports main contrib non-free
Now, the kernel that currently comes with stretch (4.9.0-8) is missing some important configurations: CONFIG_DRM_AMDGPU_SI, and CONFIG_DRM_AMDGPU_CIK. So you will need to install the latest one from the backports which does have the correct configuration.
$ sudo apt install -t stretch-backports linux-image-amd64
Next thing is getting the proper firmware
$ sudo apt install -t stretch-backports firmware-linux-nonfree
This will also update the firmware-amd-graphics which provides the binary blobs that are needed by the amdgpu driver to work properly. The old version does not support the new Polaris 12 architecture used by the RX 550, while the version from the backports (20180825) does support Polaris 12.
Now comes the part of upgrading mesa. There are a bunch binary packages that are derived from the mesa source package and we need to upgrade each one of them to version 18 (or later, but 18 is what is provided by the backports). The following two commands will upgrade any mesa related package already installed and then re-mark them as automatically installed (just to keep things tidy as they were).
sudo apt install -t stretch-backports $(grep-status -S mesa -a -FStatus "install ok installed" -s Package -n | sort -u)
sudo apt-mark auto $(grep-status -S mesa -a -FStatus "install ok installed" -s Package -n | sort -u)(credit for the last two lines). Now you can restart your computer and the RX 550 should work. You can test it using
$ DRI_PRIME=1 glxinfo | grep OpenGL
OpenGL vendor string: X.Org
OpenGL renderer string: Radeon 500 Series (POLARIS12, DRM 3.26.0, 4.18.0-0.bpo.1-amd64, LLVM 6.0.0)
OpenGL core profile version string: 4.5 (Core Profile) Mesa 18.1.6
The DRI_PRIME=1 is necessary, else glxinfo would use the integrated card.
This is not necessary, but if lspcidoes not properly display the RX 550, you will need to update the PCI IDs that are used to translate IDs to actual human-readable names.
$ sudo update-pciids
Final word, if you are using TLP for power management, it may not play nice with the RX 550. With TLP enabled I get pretty horrible performance out of it (regardless of being on AC or battery).