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<?xml version="1.0" encoding="utf-8"?>
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<feed xmlns="http://www.w3.org/2005/Atom"><title>LEdoian's Blog</title><link href="https://blog.ledoian.cz/" rel="alternate"></link><link href="https://blog.ledoian.cz/feeds/all.atom.xml" rel="self"></link><id>https://blog.ledoian.cz/</id><updated>2024-05-08T00:00:00+02:00</updated><entry><title>Only NAT packets you can deliver responses for</title><link href="https://blog.ledoian.cz/masquerade-with-filter.html" rel="alternate"></link><published>2024-05-08T00:00:00+02:00</published><updated>2024-05-08T00:00:00+02:00</updated><author><name>LEdoian</name></author><id>tag:blog.ledoian.cz,2024-05-08:/masquerade-with-filter.html</id><summary type="html"><p>When setting up a masquerading nat, it is worth considering masquerading only
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packets from known networks. That is, instead of rule like <tt class="docutils literal">iifname <span class="pre">eth-inside</span>
|
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|
masquerade</tt> use something like <tt class="docutils literal">iifname <span class="pre">eth-inside</span> ip saddr 198.51.100.0/24
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masquerade</tt>.</p>
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<p>I learned the hard way: my laptop in a masqueraded network picked …</p></summary><content type="html"><p>When setting up a masquerading nat, it is worth considering masquerading only
|
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|
packets from known networks. That is, instead of rule like <tt class="docutils literal">iifname <span class="pre">eth-inside</span>
|
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|
masquerade</tt> use something like <tt class="docutils literal">iifname <span class="pre">eth-inside</span> ip saddr 198.51.100.0/24
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masquerade</tt>.</p>
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<p>I learned the hard way: my laptop in a masqueraded network picked a wrong
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source address from a subnet the router had no knowledge about. The outbound
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packets passed through right, but the responses came in, undergone translation,
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and since the destination was unknown to the router, it used the <em>default</em>
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route, sending the packet back to the ISP.</p>
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<p>The result: IDS triggered by <em>many</em> packets from my router with source IP
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addresses from all around the Internet, all with destination to my private
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address. (The ISP was not happy about that.)</p>
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</content><category term="til"></category><category term="linux"></category></entry><entry><title>Creating own XKB tweaks</title><link href="https://blog.ledoian.cz/custom-xkb-tweaks.html" rel="alternate"></link><published>2024-04-17T16:40:00+02:00</published><updated>2024-04-17T16:40:00+02:00</updated><author><name>LEdoian</name></author><id>tag:blog.ledoian.cz,2024-04-17:/custom-xkb-tweaks.html</id><summary type="html"><p>Debugging this took me a bit too long, so I want to write about the caveat.</p>
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<p>My problem: My laptop does not have PageUp and PageDown keys, and many other
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keyboards I use have similar deficiencies. And I use various environments and
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various systems, some of which are shared with …</p></summary><content type="html"><p>Debugging this took me a bit too long, so I want to write about the caveat.</p>
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<p>My problem: My laptop does not have PageUp and PageDown keys, and many other
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keyboards I use have similar deficiencies. And I use various environments and
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various systems, some of which are shared with other people who don't need/want
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my tweaks. IOW: I want something generic, but it must be confined to my user –
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no system-wide daemon, no udev remapping. (I mostly ended up with these
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solutions when I searched for a way to remap keys on Wayland.)</p>
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<p>Requirements: xkbcommon implementation of XKB with utilities. It is quite
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common these days (duh…), but you could probably just compile this yourself if
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you don't have it.</p>
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<div class="section" id="the-tweaking">
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<h2>The tweaking</h2>
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<p>The <a class="reference external" href="https://xkbcommon.org/doc/current/user-configuration.html">xkbcommon guide</a> tells us that we
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can inspect the files in <a class="footnote-reference" href="#lazy" id="footnote-reference-1">[1]</a> <tt class="docutils literal">/usr/share/X11/xkb</tt> for the source files
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and just write our bits to <tt class="docutils literal"><span class="pre">~/.config/xkb/symbols/ledoian</span></tt>. In particular, I
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added this snippet to remap keyboard brightness controls to PageUp/Down:</p>
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<pre class="literal-block">
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partial
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xkb_symbols &quot;qs&quot; {
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key &lt;I238&gt; {[ Prior ]};
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key &lt;I237&gt; {[ Next ]};
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};
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</pre>
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<p>The key identifiers are taken e.g. from <tt class="docutils literal">xkbcli <span class="pre">interactive-wayland</span></tt>.
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However, this is KcCGST <a class="footnote-reference" href="#kccgst-vs-rmlvo" id="footnote-reference-2">[2]</a> description, but layouts are
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configured using RMLVO, so I need to define an option and tell what it should
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do. The guide wants me to create <tt class="docutils literal"><span class="pre">~/.config/xkb/rules/evdev</span></tt> with:</p>
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<pre class="literal-block">
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! option = symbols
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ledoian:qs = +ledoian(qs)
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! include %S/evdev
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</pre>
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<p>Now I just add <tt class="docutils literal">ledoian:qs</tt> <a class="footnote-reference" href="#option-vs-symbol" id="footnote-reference-3">[3]</a> to my keyboard configuration
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and… it does not work. For this, at all, but if I remap e.g. the L key, that
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gets applied. The problem? That included file says that the default keyboard
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model always includes <tt class="docutils literal">inet(evdev)</tt> symbols. Those symbols set the default
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meaning of the keys, but since that got applied later, it overrides my tweak.</p>
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<p>Solution: first include, then add my option.</p>
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<p>How to debug: read stuff that <tt class="docutils literal">xkbcli <span class="pre">compile-keymap</span> <span class="pre">--verbose</span></tt> tells you
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(pass your config as <tt class="docutils literal"><span class="pre">--layout</span></tt>, <tt class="docutils literal"><span class="pre">--variant</span></tt>, <tt class="docutils literal"><span class="pre">--options</span></tt>, …). At the top
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it says what it does:</p>
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<pre class="literal-block">
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xkbcommon: DEBUG: Include path added: /home/ledoian/.config/xkb
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xkbcommon: DEBUG: Include path added: /usr/share/X11/xkb
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xkbcommon: DEBUG: Compiling from RMLVO: rules 'evdev', model 'pc105', layout 'us', variant '(null)', options '(null)'
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xkbcommon: DEBUG: Compiling from KcCGST: keycodes 'evdev+aliases(qwerty)', types 'complete', compat 'complete', symbols 'pc+us+inet(evdev)'
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</pre>
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<p>My option would appear before the <tt class="docutils literal">inet(evdev)</tt> part.</p>
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</div>
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<div class="section" id="a-note-about-x11">
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<h2>A note about X11</h2>
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<p>X11 uses a separate implementation of XKB (the original one, in fact), which
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does _not_ look into the user directory, just the system ones. However, you can
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compile the keymap yourself using <tt class="docutils literal">xkbcli <span class="pre">compile-keymap</span> [KEYMAP OPTIONS] &gt;
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my_layout.xkb</tt> and load it into the X server with <tt class="docutils literal">xkbcomp my_layout.xkb $DISPLAY</tt>.</p>
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<hr class="docutils" />
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<table class="docutils footnote" frame="void" id="lazy" rules="none">
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<colgroup><col class="label" /><col /></colgroup>
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<tbody valign="top">
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<tr><td class="label"><a class="fn-backref" href="#footnote-reference-1">[1]</a></td><td>This is not technically accurate, really the paths reference
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<tt class="docutils literal">$XDG_something</tt> variables. I am lazy and just copied my system, so YMMV
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(probably won't, though).</td></tr>
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</tbody>
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</table>
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<table class="docutils footnote" frame="void" id="kccgst-vs-rmlvo" rules="none">
|
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<colgroup><col class="label" /><col /></colgroup>
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<tbody valign="top">
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<tr><td class="label"><a class="fn-backref" href="#footnote-reference-2">[2]</a></td><td>There are two levels of describing the keymap: the
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lowlevel one is called KcCGST (short for keycodes, compat, geometry,
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|
symbols, types) and is considered to be an implementation detail; the
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user-facing one is RMLVO (rules, model, layout, variant, options) and that
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is what you use in the configs, with <tt class="docutils literal">setxkbmap</tt> &amp;c.</td></tr>
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</tbody>
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</table>
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<table class="docutils footnote" frame="void" id="option-vs-symbol" rules="none">
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<colgroup><col class="label" /><col /></colgroup>
|
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<tbody valign="top">
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<tr><td class="label"><a class="fn-backref" href="#footnote-reference-3">[3]</a></td><td>While both this example and the <a class="reference external" href="https://www.freedesktop.org/wiki/Software/XKeyboardConfig/">upstream</a> layouts name
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the symbols and options similarly, I think they don't need to be related –
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you should be able to put whatever you want in your options to the left of
|
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|
<tt class="docutils literal">=</tt>, the right hand side is the name of the symbol file and if a
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|
non-default layout from that file is used, its name is put in the
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parentheses.</td></tr>
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</tbody>
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</table>
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</div>
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</content><category term="technology"></category><category term="lifehack"></category><category term="software"></category><category term="linux"></category></entry><entry><title>You sure you want to hear the gossip?</title><link href="https://blog.ledoian.cz/do-not-gossip-identities.html" rel="alternate"></link><published>2024-03-11T22:49:00+01:00</published><updated>2024-03-11T22:49:00+01:00</updated><author><name>LEdoian</name></author><id>tag:blog.ledoian.cz,2024-03-11:/do-not-gossip-identities.html</id><summary type="html"><p>Sometimes, not knowing something about your friends is simpler than knowing
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|
something you know you aren't supposed to know…</p>
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|
|
<p>TL;DR: If you are gossiping, please handle information which change attitude
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|
towards others with care and maybe share them with consent of the <em>listener</em>. <a class="footnote-reference" href="#on-gossiping" id="footnote-reference-1">[1]</a></p>
|
|
|
<p>Some time ago, I was …</p></summary><content type="html"><p>Sometimes, not knowing something about your friends is simpler than knowing
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|
|
something you know you aren't supposed to know…</p>
|
|
|
<p>TL;DR: If you are gossiping, please handle information which change attitude
|
|
|
towards others with care and maybe share them with consent of the <em>listener</em>. <a class="footnote-reference" href="#on-gossiping" id="footnote-reference-1">[1]</a></p>
|
|
|
<p>Some time ago, I was casually talking with my friend, let's call them Alex.
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|
For one reason or another, we got to gossip and I learnt a new, very private
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|
|
information about our mutual friend, Bay. <a class="footnote-reference" href="#names2" id="footnote-reference-2">[2]</a> I knew Bay would not
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|
|
expect me to know or possibly even want me to know at that time, yet the new
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|
|
part of their identity would require me to behave differently around Bay in
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|
|
order not to hurt them. <a class="footnote-reference" href="#non-disclosure" id="footnote-reference-3">[3]</a></p>
|
|
|
<p>That turned my interactions with Bay into a bit of a minefield:</p>
|
|
|
<ol class="arabic simple">
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|
|
<li>If I behaved according to what I learnt, I may easily overstep Bay's
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|
|
boundaries and invade their privacy, possibly quite badly. <a class="footnote-reference" href="#my-privacy" id="footnote-reference-4">[4]</a></li>
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|
|
<li>If I kept my old behaviour, I would feel like I am actively hurting Bay.</li>
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|
|
<li>If I accidentally slipped my tongue in front of Bay and they notice, I still
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|
|
ending up invading their privacy as in point 1.</li>
|
|
|
<li>I am also prone to sharing the gossip, maybe accidentally. I would be to
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|
|
someone else what Alex was to me, and I certainly didn't want to cast this
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|
|
&quot;curse&quot; on anyone. <a class="footnote-reference" href="#gossip-circumstances" id="footnote-reference-5">[5]</a></li>
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|
|
<li>If Bay subconsciously noticed I am behaving in line with their secret and in
|
|
|
another interaction I wouldn't, they could feel invalidated (without an
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|
|
obvious reason why).</li>
|
|
|
</ol>
|
|
|
<p>It sucks, it made talking to Bay needlessly stressful. Please don't do that.</p>
|
|
|
<p>So, to reiterate the message: <strong>Please gossip *safely* and *consensually* about
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|
|
stuff that is private in nature and would change attitudes towards people.</strong>
|
|
|
For the queer stuff, this can be rephrased in layman's terms as <strong>please just
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|
|
don't out other people to people who do not explicitly want to know.</strong> <a class="footnote-reference" href="#consent" id="footnote-reference-6">[6]</a></p>
|
|
|
<!-- ReST wtf, why can't I put emphasis in strong? -->
|
|
|
<p>(Again, maybe gossip safely anyway, but for the &quot;regular&quot; gossip you can
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|
|
usually hide what you know without feeling that bad.)</p>
|
|
|
<div class="section" id="final-remarks">
|
|
|
<h2>Final remarks</h2>
|
|
|
<p>I wrote this post mainly to raise awareness and help learn from past mistakes.
|
|
|
It is not meant to shame Alex for telling me, they might not have been aware
|
|
|
and neither were I at the time.</p>
|
|
|
<p>Apart from the role as &quot;me&quot; in the story, I also were &quot;Bay&quot; a few times,
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|
|
luckily not with a too intimate part of my identity. And while I try not to be
|
|
|
another &quot;Alex&quot;, I cannot rule that completely out unfortunately.</p>
|
|
|
<p>This post has been a long time in my backlog (~6 months maybe), it is not a
|
|
|
reaction to any recent gossip I have heard. (The points I make still hold ofc,
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|
|
but lately I only heard &quot;the ordinary stuff&quot; which I will probably just forget
|
|
|
and not care about without harming anyone.)</p>
|
|
|
<p>Lastly, Bay eventually told me themself, so my life is peaceful again. I didn't
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|
|
ask if I am allowed to talk about that and with whom, so I err on the safe side
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|
|
and will not write here anything else :-)</p>
|
|
|
<hr class="docutils" />
|
|
|
<table class="docutils footnote" frame="void" id="on-gossiping" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-1">[1]</a></td><td>I mean, gossiping is not nice to the mentioned person who
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|
|
doesn't usually consent, but it's not like I could prevent people from
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|
|
gossiping, so this post is not about that. Also, you can conceal your
|
|
|
knowledge of &quot;regular&quot; gossip more easily than of gossip which changes your
|
|
|
attitude.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="names2" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-2">[2]</a></td><td>I originally wanted to have the friends be Alice and Bob, but that
|
|
|
might support the narative that &quot;girls gossip&quot;, which is sexist and IME not
|
|
|
accurate (more like &quot;everyone gossips&quot;). So I made my friends be of
|
|
|
ambiguous gender and use they/them pronouns. Sorry, this might make the post
|
|
|
a bit harder to read, but the stereotypes need to die :-)</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="non-disclosure" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-3">[3]</a></td><td>I will not give any more information here. Don't try to
|
|
|
guess, I am not telling. Bay is my friend and deserves privacy. (However, if
|
|
|
you suspect that you might be the Bay of this story, by all means ask me
|
|
|
whether you are. I don't want you to feel bad / insecure / unsure / … (And
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|
|
in fact, there may be multiple Bays…))</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="my-privacy" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-4">[4]</a></td><td>There are definitely parts of my identity I do not share much
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|
|
and would probably get upset at various people (and also paranoid) if I got
|
|
|
outed. OTOH, the number of people who know my secrets is non-decreasing
|
|
|
anyway, so I try to prepare that someone unexpected inevitably will overstep
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|
|
this boundary, possibly in a good faith. (If you want to try to act upon my
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|
|
secrets, I'd appreciate you asking beforehand to avoid weird reactions.)</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="gossip-circumstances" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-5">[5]</a></td><td>Naturally, this gossip sharing can have various
|
|
|
circumstances: Me (or Alex) being unaware that the listener (call them
|
|
|
Cameron) doesn't know, slipping my tongue in a subtle way yet Cameron
|
|
|
understanding the subtext, being drunk, … It might be difficult to keep the
|
|
|
secret in all those situations.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="consent" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-6">[6]</a></td><td>If the listener wants to know and go sweeping mines and you are
|
|
|
willing to tell them, ~~sure, tell them~~ it's up to you and I have no say
|
|
|
in that. Learn the consequences and go for the interactions you want to
|
|
|
have!</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
</div>
|
|
|
</content><category term="queer"></category><category term="relationships"></category><category term="identity"></category></entry><entry><title>Print your stuff on Möbius bands!</title><link href="https://blog.ledoian.cz/mobius-print.html" rel="alternate"></link><published>2024-03-02T18:07:00+01:00</published><updated>2024-03-03T14:59:00+01:00</updated><author><name>LEdoian</name></author><id>tag:blog.ledoian.cz,2024-03-02:/mobius-print.html</id><summary type="html"><p>I found a fun and useful way of printing stuff to ~~both~~all sides of a paper.
|
|
|
I just need to find the right printer!</p>
|
|
|
<div class="section" id="quick-recap-how-to-conventionally-print-stuff-two-sided">
|
|
|
<h2>Quick recap: how to conventionally print stuff two-sided</h2>
|
|
|
<p>A typical way is just sending the page to get printed two-sided (with setting
|
|
|
the correct way …</p></div></summary><content type="html"><p>I found a fun and useful way of printing stuff to ~~both~~all sides of a paper.
|
|
|
I just need to find the right printer!</p>
|
|
|
<div class="section" id="quick-recap-how-to-conventionally-print-stuff-two-sided">
|
|
|
<h2>Quick recap: how to conventionally print stuff two-sided</h2>
|
|
|
<p>A typical way is just sending the page to get printed two-sided (with setting
|
|
|
the correct way of flipping pages). That is, on the other side of page 1 is
|
|
|
page 2, next sheet contains pages 3,4, then 5 &amp; 6, …</p>
|
|
|
<p>This is usually trivial to print on duplex printers, a bit hard to simulate on
|
|
|
one-sided printers (but some drivers can do that) and has drawbacks when you
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|
|
need to look at stuff on other pages at the same time – you need to flip the
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|
|
sheet often, as you only can put half of the pairs of pages next to each other
|
|
|
(even one and the following odd one).</p>
|
|
|
<div class="figure">
|
|
|
<object data="https://blog.ledoian.cz/images/mobius-print/twoside.svg" style="width: 66%;" type="image/svg+xml"></object>
|
|
|
<p class="caption">Ordinary two-sided printing. Red arrows show sheet flips between consecutive
|
|
|
pages.</p>
|
|
|
</div>
|
|
|
<p>A slight improvement hack is putting two pages on the same side of the paper
|
|
|
(works well with A-series of papers, I don't know for Letters &amp;co.) – you can
|
|
|
put up to four pages of the original document next to each other, if they are
|
|
|
the right ones, but there are still pairs of pages that need turning sheets.
|
|
|
Also only works if the original pages do not have too tiny features on them.
|
|
|
<a class="footnote-reference" href="#illustrations" id="footnote-reference-1">[1]</a></p>
|
|
|
<p>Booklets are fun and approachable, but still suffer from the same issues as the
|
|
|
conventional duplex print. They might be a bit hard to print, but programs like
|
|
|
<tt class="docutils literal">pdfbook</tt> or <tt class="docutils literal">paperjam</tt> make it easy to prepare for the classic duplex
|
|
|
printing. Also, it is maybe hard to tell which page ends up where, as the order
|
|
|
is: last+first, second+penultimate, third-from-end+third, … until the pages
|
|
|
meet in the middle.</p>
|
|
|
<div class="figure">
|
|
|
<object data="https://blog.ledoian.cz/images/mobius-print/booklet.svg" style="width: 66%;" type="image/svg+xml"></object>
|
|
|
<p class="caption">The most common booklet order with two pages per side for landscape
|
|
|
orientation. (Note that we show more pages, and thus more sheet-flips; the
|
|
|
number of sheet-flips is in fact the same as for two-sided printing.)</p>
|
|
|
</div>
|
|
|
</div>
|
|
|
<div class="section" id="the-improvement-for-seeing-multiple-consecutive-pages">
|
|
|
<h2>The improvement for seeing multiple consecutive pages</h2>
|
|
|
<p>In order to be able to look simultaneously at many consecutive pages of the
|
|
|
original, I think the order of first+first-past-half, second+second-past-half,
|
|
|
… middle+last is much better (or maybe even the best). Since consecutive pages
|
|
|
end up on different sheets (whenever there are at least three pages), if the
|
|
|
original has e.g. figures on different page or long code listing, you can see
|
|
|
it all!</p>
|
|
|
<div class="figure">
|
|
|
<object data="https://blog.ledoian.cz/images/mobius-print/mobius.svg" style="width: 66%;" type="image/svg+xml"></object>
|
|
|
<p class="caption">The &quot;Möbius order&quot; of pages.</p>
|
|
|
</div>
|
|
|
<p>And this is really easy to use: You read a page and when you don't need it
|
|
|
anymore, you flip it and put to the end of the page stack <a class="footnote-reference" href="#ordering" id="footnote-reference-2">[2]</a>. If you
|
|
|
need to look at several pages, just rotate them in the same order as they go the
|
|
|
first time. <a class="footnote-reference" href="#mistake" id="footnote-reference-3">[3]</a></p>
|
|
|
<p>Need to print this? For one-sided printers this is rather easy, too: just print
|
|
|
the first half (the bigger one) on the sheets, then put them back into the tray
|
|
|
and print the rest on them. You might need to experiment which side the sheets
|
|
|
should be put in and whether you need to print the rest in reverse order, but
|
|
|
that is it.</p>
|
|
|
<p>Got the pages shuffled? Sort them by the first half, as if the print was
|
|
|
one-sided.</p>
|
|
|
<p>The only annoying thing for me is that there is not much software that could
|
|
|
reorder the pages for two-sided printing, so that you don't need to re-insert
|
|
|
the sheets back in the tray. So I <a class="reference external" href="https://blog.ledoian.cz/images/mobius-print/interleave.patch">patched</a> <a class="reference external" href="https://mj.ucw.cz/sw/paperjam/">paperjam</a> to enable this. <a class="footnote-reference" href="#multi-mobius" id="footnote-reference-4">[4]</a></p>
|
|
|
<p>And the best part? If you would try to glue consecutive pages side-to-side,
|
|
|
you'd end up with a Möbius band! So if you get a Möbius paper, you can just
|
|
|
print this one-sided (duh :-D)</p>
|
|
|
</div>
|
|
|
<div class="section" id="honorable-mention-leporello">
|
|
|
<h2>Honorable mention: leporello</h2>
|
|
|
<p>Printing leporellos (aka concertina folded) also has many of the same benefits,
|
|
|
since there is only one pair of consecutive pages that need a page flip. The
|
|
|
order is first+last, second+penultimate, … and the original pages can be
|
|
|
shuffled this way with <tt class="docutils literal">paperjam</tt> or simply using the other order for the
|
|
|
second side printing, than for the Möbius band. But there is a bit of fun
|
|
|
topology missing here :-)</p>
|
|
|
<div class="figure">
|
|
|
<object data="https://blog.ledoian.cz/images/mobius-print/leporello.svg" style="width: 66%;" type="image/svg+xml"></object>
|
|
|
<p class="caption">A leporello order is also quite good, with only one sheet-flip in the entire
|
|
|
document.</p>
|
|
|
</div>
|
|
|
</div>
|
|
|
<div class="section" id="is-this-the-best-order">
|
|
|
<h2>Is this the best order?</h2>
|
|
|
<p>Yes, if &quot;best&quot; means &quot;the minimum difference of numbers of pages that get put
|
|
|
on the same sheet is as big as possible&quot;. The proof is left as an exercise for
|
|
|
the reader.</p>
|
|
|
<!-- Hint: you cannot pair the middle page to anything else to get a better
|
|
|
result. -->
|
|
|
<p>Of course, this holds for a set of pages with no additional assumptions. In
|
|
|
ordinary print, having a sheet-turn between chapters is fine and under similar
|
|
|
guarantees other approaches may yield better results.</p>
|
|
|
</div>
|
|
|
<div class="section" id="cheat-sheet-paperjam-commands">
|
|
|
<h2>Cheat sheet: paperjam commands</h2>
|
|
|
<table border="1" class="docutils">
|
|
|
<caption>Various commands for ordering pages for duplex printing with paperjam.</caption>
|
|
|
<thead valign="bottom">
|
|
|
<tr><th class="head">Order</th>
|
|
|
<th class="head">Command</th>
|
|
|
</tr>
|
|
|
</thead>
|
|
|
<tbody valign="top">
|
|
|
<tr><td>Classic two-sided</td>
|
|
|
<td><tt class="docutils literal">null</tt></td>
|
|
|
</tr>
|
|
|
<tr><td>Two pages per side</td>
|
|
|
<td><tt class="docutils literal">nup(2)</tt></td>
|
|
|
</tr>
|
|
|
<tr><td>Booklet</td>
|
|
|
<td><tt class="docutils literal">book</tt> (follow with <tt class="docutils literal">nup(2)</tt> for actual booklet print)</td>
|
|
|
</tr>
|
|
|
<tr><td>Leporello</td>
|
|
|
<td><tt class="docutils literal">modulo(2) {1 2} modulo(1,half) {1 <span class="pre">-1}</span></tt> (The first <tt class="docutils literal">modulo</tt> just adds blank pages to the end.)</td>
|
|
|
</tr>
|
|
|
<tr><td>Möbius (with patch)</td>
|
|
|
<td><tt class="docutils literal">interleave(2)</tt></td>
|
|
|
</tr>
|
|
|
<tr><td>Möbius (known page count)</td>
|
|
|
<td><tt class="docutils literal">select <span class="pre">{1..5</span> <span class="pre">10..6}</span> modulo(1,half) {1 <span class="pre">-1}</span></tt></td>
|
|
|
</tr>
|
|
|
<tr><td>Multiple Möbius bands, odd-even</td>
|
|
|
<td><tt class="docutils literal">modulo(4) {1 3 2 4}</tt></td>
|
|
|
</tr>
|
|
|
<tr><td>Multiple bands, &quot;modulo 3&quot;</td>
|
|
|
<td><tt class="docutils literal">modulo(6) {1 4 2 5 3 6}</tt></td>
|
|
|
</tr>
|
|
|
<tr><td>Second half (smaller) of pages in reverse order</td>
|
|
|
<td><tt class="docutils literal">modulo(1,half) <span class="pre">{-1}</span></tt></td>
|
|
|
</tr>
|
|
|
<tr><td>Second half (smaller) of pages in normal order</td>
|
|
|
<td><tt class="docutils literal">modulo(1,half) <span class="pre">{-1}</span> modulo(1) <span class="pre">{-1}</span></tt></td>
|
|
|
</tr>
|
|
|
<tr><td>First half (bigger) of pages</td>
|
|
|
<td><tt class="docutils literal">modulo(2) {1 2} modulo(1,half) {1}</tt></td>
|
|
|
</tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<p>I might create more patches for avoiding the weird <tt class="docutils literal">modulo</tt> commands…</p>
|
|
|
<hr class="docutils" />
|
|
|
<table class="docutils footnote" frame="void" id="illustrations" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-1">[1]</a></td><td>Most of the figures in this article are drawn with a single
|
|
|
page per a side of a sheet. I consider putting more pages on a single side
|
|
|
of paper to be an implementation detail, because it is not always possible
|
|
|
(e.g. with too small font) and sometimes you could put more than two pages
|
|
|
on a single side of paper, which leads to the fact that if you put
|
|
|
everything on one side of the paper, you can see everything at once and save
|
|
|
the other side. Not very useful though… My only exception is the booklet
|
|
|
printing below, because that one seems to be rather common.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="ordering" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-2">[2]</a></td><td>See how this neatly puts the first-past-half page right after
|
|
|
the half of the stack? Awesome!</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="mistake" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-3">[3]</a></td><td>Also, if you flip the page around the wrong edge, you can just
|
|
|
rotate the rest of the stack and end up with the correct orientation.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="multi-mobius" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-4">[4]</a></td><td>A slight variation for which I can generate the order
|
|
|
with upstream <tt class="docutils literal">paperjam</tt> is using this order on small subsets of pages.
|
|
|
For example, if you only want to be able to see any two consecutive pages,
|
|
|
you can do this for just four pages – the order is then 1+3, 2+4, 5+7, 6+8,…
|
|
|
Since each sheet either contains two odd or two even pages, the following
|
|
|
page is on different sheet than the previous one. And you can do this
|
|
|
&quot;modulo 3&quot; to see three pages: 1+4, 2+5, 3+6, 7+10, … This &quot;simulates&quot;
|
|
|
multiple smaller Möbius bands, but will be probably harder to use.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
</div>
|
|
|
</content><category term="technology"></category><category term="lifehack"></category><category term="print"></category></entry><entry><title>How to convert CBZ to PDF</title><link href="https://blog.ledoian.cz/cbz-to-pdf.html" rel="alternate"></link><published>2024-02-17T16:55:00+01:00</published><updated>2024-02-17T16:55:00+01:00</updated><author><name>LEdoian</name></author><id>tag:blog.ledoian.cz,2024-02-17:/cbz-to-pdf.html</id><summary type="html"><ol class="arabic simple">
|
|
|
<li>Extract the archive (cbz is just a zip, cbr is a rar, …)</li>
|
|
|
<li><dl class="first docutils">
|
|
|
<dt>Convert individual pictures to PDF using <tt class="docutils literal">img2pdf</tt></dt>
|
|
|
<dd><ul class="first last">
|
|
|
<li>Many other ways including <tt class="docutils literal">convert</tt> from ImageMagick tend to do weird stuff like breaking aspect ratios or adding margins</li>
|
|
|
</ul>
|
|
|
</dd>
|
|
|
</dl>
|
|
|
</li>
|
|
|
<li>Merge files into the single PDF, e.g. using <tt class="docutils literal">qpdf <span class="pre">--empty</span> <span class="pre">--pages …</span></tt></li></ol></summary><content type="html"><ol class="arabic simple">
|
|
|
<li>Extract the archive (cbz is just a zip, cbr is a rar, …)</li>
|
|
|
<li><dl class="first docutils">
|
|
|
<dt>Convert individual pictures to PDF using <tt class="docutils literal">img2pdf</tt></dt>
|
|
|
<dd><ul class="first last">
|
|
|
<li>Many other ways including <tt class="docutils literal">convert</tt> from ImageMagick tend to do weird stuff like breaking aspect ratios or adding margins</li>
|
|
|
</ul>
|
|
|
</dd>
|
|
|
</dl>
|
|
|
</li>
|
|
|
<li>Merge files into the single PDF, e.g. using <tt class="docutils literal">qpdf <span class="pre">--empty</span> <span class="pre">--pages</span> *.pdf <span class="pre">--</span> output.pdf</tt>.</li>
|
|
|
</ol>
|
|
|
<div class="section" id="references">
|
|
|
<h2>References</h2>
|
|
|
<ul class="simple">
|
|
|
<li><a class="reference external" href="https://askubuntu.com/questions/207172/how-to-convert-cbr-to-pdf">https://askubuntu.com/questions/207172/how-to-convert-cbr-to-pdf</a></li>
|
|
|
<li><a class="reference external" href="https://superuser.com/questions/497293/how-to-convert-calibre-cbr-to-pdf-format-in-linux">https://superuser.com/questions/497293/how-to-convert-calibre-cbr-to-pdf-format-in-linux</a></li>
|
|
|
</ul>
|
|
|
</div>
|
|
|
<div class="section" id="why">
|
|
|
<h2>Why</h2>
|
|
|
<p>My eBook reader (PocketBook Touch Lux) does not seem to be able to handle cbz.</p>
|
|
|
</div>
|
|
|
</content><category term="til"></category><category term="comics"></category><category term="software"></category></entry><entry><title>Do not forget about IPv6 DNS</title><link href="https://blog.ledoian.cz/forgetting-dns6.html" rel="alternate"></link><published>2024-01-24T03:20:00+01:00</published><updated>2024-01-24T03:20:00+01:00</updated><author><name>LEdoian</name></author><id>tag:blog.ledoian.cz,2024-01-24:/forgetting-dns6.html</id><summary type="html"><p>Do you think IPv6-only internet works OK? I am going to tell you that it does
|
|
|
not, but it is not immediately visible. TL;DR: The internet can be broken also
|
|
|
by forgetting to add AAAA records of the <em>nameservers</em>. This creates IPv4
|
|
|
requirement for the resolving even when the …</p></summary><content type="html"><p>Do you think IPv6-only internet works OK? I am going to tell you that it does
|
|
|
not, but it is not immediately visible. TL;DR: The internet can be broken also
|
|
|
by forgetting to add AAAA records of the <em>nameservers</em>. This creates IPv4
|
|
|
requirement for the resolving even when the target is reachable using IPv6.</p>
|
|
|
<div class="section" id="quick-recap">
|
|
|
<h2>Quick recap</h2>
|
|
|
<p>Connecting to a website is easy, right? You type in the name, you get the front page.</p>
|
|
|
<div class="figure">
|
|
|
<object data="https://blog.ledoian.cz/images/forgetting-dns6/image1.svg" style="width: 50%;" type="image/svg+xml"></object>
|
|
|
<p class="caption">This is a very naïve idea of connecting to a server.</p>
|
|
|
</div>
|
|
|
<p>OK, it is a bit harder: the computer needs an IP address, so we need to use
|
|
|
this magic box called DNS. The flow looks something like this:</p>
|
|
|
<div class="figure">
|
|
|
<object data="https://blog.ledoian.cz/images/forgetting-dns6/image2.svg" style="width: 50%;" type="image/svg+xml"></object>
|
|
|
<p class="caption">Slightly better, now we at least know the machine-readable address.</p>
|
|
|
</div>
|
|
|
<p>And for IPv6-only everything on the picture has to have IPv6 connectivity and AAAA DNS records.</p>
|
|
|
<div class="section" id="reaching-ipv4-land-from-ipv6-only">
|
|
|
<h3>Reaching IPv4 land from IPv6-only</h3>
|
|
|
<p>There are few^H^H^Hmany sites that still only support IPv4. To reach them, we
|
|
|
need someone who can reach both the IPv4- and IPv6-land to go there on our
|
|
|
behalf – a proxy. This proxy can be ad-hoc (I often use <tt class="docutils literal">ssh <span class="pre">-D</span></tt>) or there
|
|
|
are well-known protocols like NAT64 with DNS64 to do that in a standard and
|
|
|
lightweight manner. <a class="footnote-reference" href="#nat44" id="footnote-reference-1">[1]</a>
|
|
|
In that case, the connection looks like this:</p>
|
|
|
<div class="figure">
|
|
|
<object data="https://blog.ledoian.cz/images/forgetting-dns6/image3.svg" style="width: 100%;" type="image/svg+xml"></object>
|
|
|
<p class="caption">And now we can reach the whole internet.</p>
|
|
|
</div>
|
|
|
<p>You might already know that you need some workaround like this to reach GitHub.
|
|
|
What I think you might not know, you need similar workaround to reach the Wikipedia.</p>
|
|
|
<p>Disclaimer: I like Wikipedia and this is not meant to shame them, just use as
|
|
|
an example. I am aware of several other sites suffering from the same problem,
|
|
|
including at least one IPv6 test. <a class="footnote-reference" href="#test-aaaa" id="footnote-reference-2">[2]</a> (It would be nice if they added
|
|
|
the missing piece in the puzzle, though.)</p>
|
|
|
</div>
|
|
|
</div>
|
|
|
<div class="section" id="enter-dns">
|
|
|
<h2>Enter DNS</h2>
|
|
|
<p>Our picture has one unexplored magic box: the DNS. As per the definition (which
|
|
|
I just made up and was not bothered to even fully formulate):</p>
|
|
|
<blockquote>
|
|
|
yada yada distributed database of records attached to the strings – domain
|
|
|
names. The records hold various information about the domain depending on the type.</blockquote>
|
|
|
<p>There are three interesting types of records: A records give IPv4 addresses,
|
|
|
AAAA give IPv6 addresses and NS give names of servers who know about the
|
|
|
particular subtree of the database. And to actually resolve the final AAAA
|
|
|
record the (recursive) resolver starts at the <em>root zone</em> and tries to find
|
|
|
the answer. <a class="footnote-reference" href="#dns-simplification" id="footnote-reference-3">[3]</a> The resolution algorithm can be visualised like this:</p>
|
|
|
<div class="figure">
|
|
|
<object data="https://blog.ledoian.cz/images/forgetting-dns6/image4.svg" style="width: 100%;" type="image/svg+xml"></object>
|
|
|
<p class="caption">Yeah, it's a mess.</p>
|
|
|
</div>
|
|
|
<p>There is one extra tricky bit: the NS records contain <em>names</em>, not addresses,
|
|
|
so when resolving we need <em>two</em> queries for each layer (very simplified):
|
|
|
first we ask for the final domain (<tt class="docutils literal">blog.ledoian.cz</tt>) and get a NS record
|
|
|
(when the server does not have the answer) and then we need to ask for the A or
|
|
|
AAAA record of the name from that record, so that we can connect to the server
|
|
|
mentioned in the NS record. (This allows a nameserver to be made redundant
|
|
|
and/or reside on other types of network.)</p>
|
|
|
<p>You might start to see the issue. When the DNS was just a black box, we could
|
|
|
paint the whole picture green and call it a day. And from the regular user's
|
|
|
point of view, that is the case, just use some public DNS like 1.1.1.1, 8.8.8.8
|
|
|
or 9.9.9.9. Oh, right, I meant these easy-to-remember addresses:
|
|
|
2606:4700:4700::1111, 2001:4860:4860::8888 and 2620:fe::fe, respectively. The
|
|
|
point is, they will give you the answer because they are dual-stack, not IPv6-only.</p>
|
|
|
<p>In a way, those servers (or other dual-stack resolvers) act like another proxy,
|
|
|
similar to the SSH, NAT64 and NAT44 ones mentioned earlier. This may not be
|
|
|
much of a problem for many people. But if you have any reason to use your own
|
|
|
recursive DNS server (privacy reasons, DNSSEC validation, ISP provides bad
|
|
|
service, you are the ISP, …) <em>inside</em> an IPv6-only network, you <em>will</em> have
|
|
|
issues. <a class="footnote-reference" href="#dns-behind-nat64" id="footnote-reference-4">[4]</a></p>
|
|
|
</div>
|
|
|
<div class="section" id="example-wikipedia">
|
|
|
<h2>Example: Wikipedia</h2>
|
|
|
<p>Let's now see this in action. You know Wikipedia, right? And you can reach
|
|
|
Wikipedia on IPv6, right? It has an AAAA record (don't mind the CNAME, that
|
|
|
means that the server is really called some other way):</p>
|
|
|
<pre class="literal-block">
|
|
|
$ dig en.wikipedia.org AAAA
|
|
|
[…]
|
|
|
en.wikipedia.org. 18737 IN CNAME dyna.wikimedia.org.
|
|
|
dyna.wikimedia.org. 323 IN AAAA 2a02:ec80:600:ed1a::1
|
|
|
</pre>
|
|
|
<p>And this record does work:</p>
|
|
|
<pre class="literal-block">
|
|
|
$ ncat --ssl 2a02:ec80:600:ed1a::1 443 &lt;&lt;GO
|
|
|
GET /wiki/Main_Page HTTP/1.1
|
|
|
Host: en.wikipedia.org
|
|
|
|
|
|
GO
|
|
|
HTTP/1.1 200 OK
|
|
|
[…]
|
|
|
content-language: en
|
|
|
content-type: text/html; charset=UTF-8
|
|
|
content-length: 98078
|
|
|
|
|
|
&lt;!DOCTYPE html&gt;
|
|
|
[…]
|
|
|
</pre>
|
|
|
<p>But we can dig deeper: let's see what servers we are really asking:</p>
|
|
|
<pre class="literal-block">
|
|
|
$ dig en.wikipedia.org AAAA +trace
|
|
|
|
|
|
; &lt;&lt;&gt;&gt; DiG … &lt;&lt;&gt;&gt; en.wikipedia.org AAAA +trace
|
|
|
;; global options: +cmd
|
|
|
. 78918 IN NS e.root-servers.net.
|
|
|
. 78918 IN NS f.root-servers.net.
|
|
|
. 78918 IN NS g.root-servers.net.
|
|
|
. 78918 IN NS h.root-servers.net.
|
|
|
. 78918 IN NS i.root-servers.net.
|
|
|
. 78918 IN NS j.root-servers.net.
|
|
|
. 78918 IN NS k.root-servers.net.
|
|
|
. 78918 IN NS l.root-servers.net.
|
|
|
. 78918 IN NS m.root-servers.net.
|
|
|
. 78918 IN NS a.root-servers.net.
|
|
|
. 78918 IN NS b.root-servers.net.
|
|
|
. 78918 IN NS c.root-servers.net.
|
|
|
. 78918 IN NS d.root-servers.net.
|
|
|
;; Received 525 bytes from … in 0 ms
|
|
|
|
|
|
org. 172800 IN NS c0.org.afilias-nst.info.
|
|
|
org. 172800 IN NS a2.org.afilias-nst.info.
|
|
|
org. 172800 IN NS a0.org.afilias-nst.info.
|
|
|
org. 172800 IN NS b0.org.afilias-nst.org.
|
|
|
org. 172800 IN NS b2.org.afilias-nst.org.
|
|
|
org. 172800 IN NS d0.org.afilias-nst.org.
|
|
|
;; Received 788 bytes from 202.12.27.33#53(m.root-servers.net) in 24 ms
|
|
|
|
|
|
wikipedia.org. 3600 IN NS ns0.wikimedia.org.
|
|
|
wikipedia.org. 3600 IN NS ns1.wikimedia.org.
|
|
|
wikipedia.org. 3600 IN NS ns2.wikimedia.org.
|
|
|
;; Received 658 bytes from 2001:500:48::1#53(b2.org.afilias-nst.org) in 20 ms
|
|
|
|
|
|
en.wikipedia.org. 86400 IN CNAME dyna.wikimedia.org.
|
|
|
;; Received 94 bytes from 208.80.153.231#53(ns1.wikimedia.org) in 132 ms
|
|
|
</pre>
|
|
|
<p>Hey, there are IPv4 addresses in there! I know, this is cheating, the output is
|
|
|
from a dual-stack machine. But we can still simulate IPv6-only resolution
|
|
|
by adding <tt class="docutils literal"><span class="pre">-6</span></tt> flag:</p>
|
|
|
<pre class="literal-block">
|
|
|
$ dig en.wikipedia.org AAAA +trace -6
|
|
|
|
|
|
; &lt;&lt;&gt;&gt; DiG … &lt;&lt;&gt;&gt; en.wikipedia.org AAAA +trace -6
|
|
|
;; global options: +cmd
|
|
|
. 78915 IN NS d.root-servers.net.
|
|
|
. 78915 IN NS e.root-servers.net.
|
|
|
. 78915 IN NS f.root-servers.net.
|
|
|
. 78915 IN NS g.root-servers.net.
|
|
|
. 78915 IN NS h.root-servers.net.
|
|
|
. 78915 IN NS i.root-servers.net.
|
|
|
. 78915 IN NS j.root-servers.net.
|
|
|
. 78915 IN NS k.root-servers.net.
|
|
|
. 78915 IN NS l.root-servers.net.
|
|
|
. 78915 IN NS m.root-servers.net.
|
|
|
. 78915 IN NS a.root-servers.net.
|
|
|
. 78915 IN NS b.root-servers.net.
|
|
|
. 78915 IN NS c.root-servers.net.
|
|
|
;; Received 525 bytes from … in 0 ms
|
|
|
|
|
|
org. 172800 IN NS d0.org.afilias-nst.org.
|
|
|
org. 172800 IN NS c0.org.afilias-nst.info.
|
|
|
org. 172800 IN NS b2.org.afilias-nst.org.
|
|
|
org. 172800 IN NS a0.org.afilias-nst.info.
|
|
|
org. 172800 IN NS b0.org.afilias-nst.org.
|
|
|
org. 172800 IN NS a2.org.afilias-nst.info.
|
|
|
;; Received 816 bytes from 2001:500:2::c#53(c.root-servers.net) in 8 ms
|
|
|
|
|
|
wikipedia.org. 3600 IN NS ns0.wikimedia.org.
|
|
|
wikipedia.org. 3600 IN NS ns1.wikimedia.org.
|
|
|
wikipedia.org. 3600 IN NS ns2.wikimedia.org.
|
|
|
couldn't get address for 'ns0.wikimedia.org': not found
|
|
|
couldn't get address for 'ns1.wikimedia.org': not found
|
|
|
couldn't get address for 'ns2.wikimedia.org': not found
|
|
|
dig: couldn't get address for 'ns0.wikimedia.org': no more
|
|
|
</pre>
|
|
|
<p>Some of those IPv4 addresses were benign – the respective servers are reachable
|
|
|
both using IPv4 and IPv6 address or there is an alternative server that is
|
|
|
reachable using IPv6. That is the case for the root nameserver – in the second
|
|
|
case, we used C, which has IPv6 address (2001:500:2::c). In fact, the M server
|
|
|
also has IPv6 address, but dig chose the IPv4 one (it should not matter):</p>
|
|
|
<pre class="literal-block">
|
|
|
$ dig m.root-servers.net AAAA
|
|
|
[…]
|
|
|
m.root-servers.net. 77991 IN AAAA 2001:dc3::35
|
|
|
</pre>
|
|
|
<p>But the latter case is the bigger issue. For the domain <tt class="docutils literal">wikipedia.org</tt> there
|
|
|
are three nameservers:</p>
|
|
|
<pre class="literal-block">
|
|
|
$ dig wikipedia.org NS -6
|
|
|
[…]
|
|
|
wikipedia.org. 86400 IN NS ns0.wikimedia.org.
|
|
|
wikipedia.org. 86400 IN NS ns1.wikimedia.org.
|
|
|
wikipedia.org. 86400 IN NS ns2.wikimedia.org.
|
|
|
</pre>
|
|
|
<p>This is the last answer that we could get on an IPv6-only network, because none of
|
|
|
these three servers has AAAA record (some of them may have IPv6 address unknown to us):</p>
|
|
|
<pre class="literal-block">
|
|
|
$ dig ns0.wikimedia.org AAAA
|
|
|
[…]
|
|
|
;; Got answer:
|
|
|
;; -&gt;&gt;HEADER&lt;&lt;- opcode: QUERY, status: NOERROR, id: 59468
|
|
|
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1
|
|
|
</pre>
|
|
|
<p>The NOERROR status says the domain name exists, but we got zero answers for
|
|
|
AAAA records. This is the case for all three nameservers. And here is the
|
|
|
ultimate picture of what is happening and what goes wrong.</p>
|
|
|
<div class="figure">
|
|
|
<object data="https://blog.ledoian.cz/images/forgetting-dns6/image5.svg" style="width: 100%;" type="image/svg+xml"></object>
|
|
|
<p class="caption">The breakage in action</p>
|
|
|
</div>
|
|
|
<p>Also note that the connection from the laptop to the DNS resolver may in fact
|
|
|
consist of a chain of several (caching, non-recursive) DNS resolvers, so that
|
|
|
the final DNS resolver can have dual-stack connectivity.</p>
|
|
|
</div>
|
|
|
<div class="section" id="the-problems-with-this-state">
|
|
|
<h2>The problems with this state</h2>
|
|
|
<p>So, what is the deal. We <em>just</em> need to have a dual-stack DNS resolver
|
|
|
somewhere, and that's it, no? Well, yes but actually yes.</p>
|
|
|
<p>There are two problems with this: First, this means that any new ISP needs to
|
|
|
have <em>at least some</em> IPv4 address, even if they intend to just use IPv6
|
|
|
services. IPv4 addresses are scarce, <a class="reference external" href="https://blog.apnic.net/2021/12/16/opinion-ipv4-address-markets/">expensive</a> and small
|
|
|
blocks <a class="reference external" href="https://labs.ripe.net/author/stephen_strowes/visibility-of-ipv4-and-ipv6-prefix-lengths-in-2019/">don't route well</a>,
|
|
|
which is not great both from the
|
|
|
new ISP's and from overal routing's point of view. It also hinders IPv6
|
|
|
deployment and postpones IPv4 abandonment, needlessly.</p>
|
|
|
<p>The second issue is that this is not very visible. We are building IPv6 world,
|
|
|
but deep inside it still relies on IPv4, which might lead to great surprise
|
|
|
when we start cutting off IPv4 internet. And it might lead to false sense of
|
|
|
having IPv6 deployed, which is not true to the whole extent.</p>
|
|
|
<p>Insert &quot;It was DNS&quot; meme here.</p>
|
|
|
</div>
|
|
|
<div class="section" id="solution">
|
|
|
<h2>Solution</h2>
|
|
|
<p>The solution of this state is simple: get IPv6 connectivity to your
|
|
|
authoritative DNS server (or use another) and do not forget to add an AAAA
|
|
|
record for it in DNS. If the DNS server already has IPv6 it is probably just
|
|
|
a matter of adding a single line to the zone file (and a second one for the DNSSEC
|
|
|
signature), which should not be a big deal.</p>
|
|
|
<p>Unfortunately, this needs to be done for the whole DNS chain.
|
|
|
Especially domain names at universities are infamous for very nested domains.
|
|
|
A domain name may look like
|
|
|
<tt class="docutils literal"><span class="pre">machine.department.location.faculty.university.some-common.suffix</span></tt>. That
|
|
|
tree is deep and so is the resolution of this problem.</p>
|
|
|
</div>
|
|
|
<div class="section" id="amusing-bug-of-almost-good-deployment">
|
|
|
<h2>Amusing bug of almost good deployment</h2>
|
|
|
<p>We have seen there may be multiple NS records for a domain and thus
|
|
|
multiple nameservers. This is good for redundancy. But this does not mean that
|
|
|
the servers will have the same records – they are only supposed to give
|
|
|
equivalent answers (as far as I know).</p>
|
|
|
<p>I have come across a silly misconfiguration: a domain which has several
|
|
|
nameservers, which serve a <em>slightly</em> different set of NS records for its
|
|
|
subdomain. Specifically, the servers which were only reachable using IPv4 were
|
|
|
<em>exactly</em> the servers that knew about one additional nameserver for the
|
|
|
subdomain, which, incidentally, was the <em>only</em> one that was IPv6-capable.</p>
|
|
|
<p>So, while all the correct records were present in DNS (somewhat/somewhere), this still
|
|
|
meant that IPv6-only resolution was doomed to fail because the IPv6 nameserver
|
|
|
chain was broken. (This has already been fixed.)</p>
|
|
|
<hr class="docutils" />
|
|
|
<table class="docutils footnote" frame="void" id="nat44" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-1">[1]</a></td><td>This is very much the same as when you try to reach the
|
|
|
IPv4-public-land from IPv4-private-land, that is, from a private range of IP
|
|
|
addresses. This is called either just NAT, or NAT44 to denote IPv4-to-IPv4 NAT.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="test-aaaa" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-2">[2]</a></td><td>There are several more tests that do not even have the AAAA
|
|
|
record, lol.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="dns-simplification" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-3">[3]</a></td><td>In my example, there is a single recursive DNS
|
|
|
resolver external to my machine in order not to complicate it too much.
|
|
|
The real deployment is often trickier.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="dns-behind-nat64" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-4">[4]</a></td><td>I have not yet tried to run a recursive DNS in a network
|
|
|
with DNS64 and NAT64. Could be fun :-D My wild guess is that I would need
|
|
|
CLAT (i.e. the full 464XLAT deployment) to make that work, since the
|
|
|
resolver is connecting directly to IPv4 addresses and would need to learn to
|
|
|
use NAT64 to resolve them. (The CLAT could be built right into the resolver,
|
|
|
though).</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
</div>
|
|
|
</content><category term="networking"></category><category term="ipv6-only"></category><category term="dns"></category></entry><entry><title>About this blog</title><link href="https://blog.ledoian.cz/about-blog.html" rel="alternate"></link><published>2024-01-10T16:47:00+01:00</published><updated>2024-01-10T16:47:00+01:00</updated><author><name>LEdoian</name></author><id>tag:blog.ledoian.cz,2024-01-10:/about-blog.html</id><summary type="html"><p>This is my blog and this article describes its setup and other details about my
|
|
|
intentions. The actual <a class="reference internal" href="#the-setup">setup</a> is probably the most
|
|
|
interesting tech-wise.</p>
|
|
|
<div class="section" id="what-is-this">
|
|
|
<h2>What is this?</h2>
|
|
|
<p>My own space on the internet where I can post whatever and link others to it.
|
|
|
It might end up containing rants …</p></div></summary><content type="html"><p>This is my blog and this article describes its setup and other details about my
|
|
|
intentions. The actual <a class="reference internal" href="#the-setup">setup</a> is probably the most
|
|
|
interesting tech-wise.</p>
|
|
|
<div class="section" id="what-is-this">
|
|
|
<h2>What is this?</h2>
|
|
|
<p>My own space on the internet where I can post whatever and link others to it.
|
|
|
It might end up containing rants, guides, ideas, or maybe nothing at all in the
|
|
|
end. Only the future will tell.</p>
|
|
|
<p>The blog might even serve as my personal web page/introduction. Maybe. Maybe not…</p>
|
|
|
<p>The main motivation is to have low-effort way to post random stuff. Which leads
|
|
|
to my requirements for this thing.</p>
|
|
|
</div>
|
|
|
<div class="section" id="requirements">
|
|
|
<h2>Requirements</h2>
|
|
|
<p>(The requirements are a bit too idealistic, so not all of them were satisfied…)</p>
|
|
|
<ul class="simple">
|
|
|
<li>low-effort, me-friendly, low-maintenance – I don't want to have to learn too
|
|
|
many new technologies to use this. This includes the required technologies:
|
|
|
Python, Markdown/reStructuredText, Jinja2, git, …</li>
|
|
|
<li>Technical and math content ~~friendly~~ compatible – I expect that to appear
|
|
|
here.</li>
|
|
|
<li>Static site – for security, coolness factor and control. Also static on the
|
|
|
front-end, because I don't like JavaScript and/or running untrusted code on
|
|
|
my machine (even when in a sandbox). The SSG should likely be aimed at
|
|
|
creating blogs, not documentation. Also, self-contained, as in not depending
|
|
|
on third-party sites.</li>
|
|
|
<li>No moving parts in the infrastructure (or as few as possible) – if it works
|
|
|
on my machine, it should just get mirrored to the public site with as few
|
|
|
modifications as possible.</li>
|
|
|
<li>Transparent – I should be able to understand it, maybe others could also use
|
|
|
it as a resource or take inspiration. (At one point, this deployment itself
|
|
|
started being interesting, so if I can share the background as well as the
|
|
|
final webpage, it would be cool.)</li>
|
|
|
<li>Followable – I know you internet guys like to ~~stalk~~ follow people :-)</li>
|
|
|
<li>Aligned with my values: minimalist, simple, extensible/hackable, FLOSS</li>
|
|
|
<li>If the platform could distinguish translations and do strikethroughs, it would
|
|
|
be nice, but that is not a hard requirement.</li>
|
|
|
</ul>
|
|
|
<p>There are several features of conventional blogs that I consider to be a
|
|
|
non-goals or even anti-goals. Mostly it is about interactivity – I don't aim
|
|
|
for having any kind of comments here, or really anything that would require
|
|
|
JavaScript or complex HTML/CSS. And appearance goes past me as well, I instead
|
|
|
try to let the browser decide how to display this page – more on that <a class="reference internal" href="#design-considerations">below</a>.</p>
|
|
|
<p>The workflow I wanted to achieve is something like: Write the content, git it,
|
|
|
build it (locally, no CI/CD), push it, done. Single write, single push, very
|
|
|
simple.</p>
|
|
|
<p>And I managed to achieve something like that, via learning (too much?) about
|
|
|
git.</p>
|
|
|
<!-- TODO: fix the worktree bug already! -->
|
|
|
</div>
|
|
|
<div class="section" id="the-setup">
|
|
|
<h2>The setup</h2>
|
|
|
<p>Naturally for a sysadmin/netadmin, the setup consists of 7 ~~ISO/OSI~~ layers:</p>
|
|
|
<ol class="arabic simple">
|
|
|
<li><strong>Physical layer</strong>: cheap Hetzner VPS. Not physical, but whatever.</li>
|
|
|
<li><strong>Network layer</strong>: Nginx</li>
|
|
|
<li><strong>Persistence layer</strong>: <a class="reference external" href="https://gitea.ledoian.cz/LEdoian/blog">this git repo</a>. I will elaborate below why can
|
|
|
you see this both rendered here and in the source form in Forgejo.</li>
|
|
|
<li><strong>Content layer</strong>: Markdown or reStructuredText files.</li>
|
|
|
<li><strong>Business logic layer</strong>: <a class="reference external" href="https://getpelican.com">Pelican</a>. It's rather
|
|
|
popular and written in Python, I didn't look further.</li>
|
|
|
<li><strong>Presentation layer</strong>: I hacked my own theme, because I didn't like any in
|
|
|
the <a class="reference external" href="https://github.com/getpelican/pelican-themes">pelican-themes repo</a>.
|
|
|
I was a bit inspired by the layout of <a class="reference external" href="https://eev.ee/blog">eevee's blog</a>, but I wanted a dark theme. And as you can see, I
|
|
|
can't do quality frontend, so it ended up horrible… :-D</li>
|
|
|
<li><strong>Stalking layer</strong>: Pelican's built-in RSS and Atom feed generators. Not
|
|
|
linked from anywhere at the moment, but <a class="reference external" href="https://gitea.ledoian.cz/LEdoian/blog/src/branch/blog/output/feeds">the repo will tell you</a> what
|
|
|
hides under the <tt class="docutils literal">/feeds/</tt> path. Or you can utilize the repo (for personal
|
|
|
use – the content's license is not decided at the moment)…</li>
|
|
|
</ol>
|
|
|
<p>Most of this is straightforward, the fancy part is my repo. The repo contains
|
|
|
both source and rendered content, so that I can point Nginx right at a checkout
|
|
|
and have Git solve both persistence and deployment without additional moving
|
|
|
parts.</p>
|
|
|
<p>There are two tricks in the configuration of Git repositories: pushing to a
|
|
|
checked out repo is enabled by configuring <tt class="docutils literal">receive.denyCurrentBranch =
|
|
|
updateInstead</tt> in the target repository (which is just a normal repo, not a
|
|
|
bare one), and then I just told my source repositories <a class="footnote-reference" href="#multiple-src" id="footnote-reference-1">[1]</a> to use
|
|
|
two push targets for the remote (the first line <em>replaces</em> the original push
|
|
|
address for some reason):</p>
|
|
|
<pre class="literal-block">
|
|
|
git remote set-url --add --push blog_remote gitea&#64;gitea.ledoian.cz:LEdoian/blog.git
|
|
|
git remote set-url --add --push blog_remote blog_user&#64;blog.ledoian.cz:blog_dir
|
|
|
</pre>
|
|
|
<p>The blog user is just a user with SSH access via authorized keys, no special
|
|
|
sauce there. Nginx is then pointed to serve <tt class="docutils literal">~blog_user/blog_dir/output/</tt> at
|
|
|
<tt class="docutils literal">blog.ledoian.cz</tt>. (The <tt class="docutils literal"><span class="pre">git-remote(1)</span></tt> manpage requires me to have both
|
|
|
repositories in sync, but as long as I configure all my repositories this way,
|
|
|
I should be safe, and I think I could get away with my blog checkout getting
|
|
|
behind accidentally.)</p>
|
|
|
</div>
|
|
|
<div class="section" id="my-workflow-and-lots-of-drafts">
|
|
|
<h2>My workflow and lots of drafts</h2>
|
|
|
<p>It's Git so it's only natural for me to use various branches and repositories
|
|
|
even for a dumb blog. There are in fact 4 stages an article may go through <a class="footnote-reference" href="#skipping-stages" id="footnote-reference-2">[2]</a>:</p>
|
|
|
<ol class="arabic">
|
|
|
<li><p class="first">A private draft: lives on a branch <tt class="docutils literal">priv/something</tt>, may contain private
|
|
|
infos (like when I would just copy-paste from terminal without redaction)
|
|
|
and this branch will probably never be merged to the main repo. Nothing
|
|
|
about these branches is guaranteed.</p>
|
|
|
</li>
|
|
|
<li><p class="first">A public WIP draft: uses a branch called <tt class="docutils literal">pub/something</tt> which is pushed
|
|
|
to Forgejo (and in fact also to the blog itself, but that is just an
|
|
|
implementation detail). The draft is either does not build or is very
|
|
|
incomplete and I expect to add stuff in a way that could break the build, so
|
|
|
I put it on a separate branch. The branch will be probably merged to the
|
|
|
main branch (called <tt class="docutils literal">blog</tt>) when it is ready.</p>
|
|
|
<p>The <tt class="docutils literal">pub/…</tt> branches can be created either manually or by cherry-picking
|
|
|
from the respective <tt class="docutils literal">priv/…</tt> branch, but that will likely not be
|
|
|
distinguishable. (I am too lazy to keep the references even in the commit
|
|
|
logs.)</p>
|
|
|
</li>
|
|
|
<li><p class="first">When a draft is almost ready (or the content has simple syntax), it gets
|
|
|
placed on the <tt class="docutils literal">blog</tt> branch. The only thing that designates it as a draft
|
|
|
is <tt class="docutils literal">status: draft</tt> in the frontmatter, which means that the article will
|
|
|
get rendered and put somewhere on the public blog, but not reachable from
|
|
|
the title page (&quot;unlisted&quot;).</p>
|
|
|
</li>
|
|
|
<li><p class="first">Of course, eventually (and hopefully) the article gets published for
|
|
|
everyone to see. At that point, it is complete (or at least that is what I
|
|
|
thought when marking it as published). Possibly it might be updated in the
|
|
|
future, but no such update is anticipated at the moment of publishing. <a class="footnote-reference" href="#update-this" id="footnote-reference-3">[3]</a></p>
|
|
|
</li>
|
|
|
</ol>
|
|
|
<p>I use Git to synchronize my private branches among machines, so there are
|
|
|
actually two &quot;server-side&quot; repositories (private and public one) and thus two
|
|
|
remotes. <a class="footnote-reference" href="#private-branches-wish" id="footnote-reference-4">[4]</a></p>
|
|
|
<p>As for the actual workflow, for the main branch it usually consists of: writing
|
|
|
content, committing it, building the web, checking it locally, committing the
|
|
|
built blog and pushing it. Sometimes I do the commits together, but I always
|
|
|
separate the rendering/building commits from the content-creating ones, so that
|
|
|
I can handle those differently if needed (i.e. there is no point in
|
|
|
cherry-picking the built content, I can generate it). <a class="footnote-reference" href="#git-purists" id="footnote-reference-5">[5]</a></p>
|
|
|
<p>For other branches I use some applicable subset of the steps above, probably.</p>
|
|
|
</div>
|
|
|
<div class="section" id="design-considerations">
|
|
|
<h2>Design considerations</h2>
|
|
|
<p>The appearance of the blog is maybe not nice. That is for two reasons: I don't
|
|
|
have the right idea about how to make it much better and I want to have a
|
|
|
rather simple CSS for the web. The latter wish is because I tend to tweak
|
|
|
appearance of sites I visit using my own styles, so I would like you to be able
|
|
|
to do the same.</p>
|
|
|
<p>And for the former reason, if you have any ideas / improvements (including user
|
|
|
styles), hit me at <a class="reference external" href="mailto:blog&#64;pokemon.ledoian.cz">blog&#64;pokemon.ledoian.cz</a> :-)</p>
|
|
|
<p>My overall idea is a dark-by-default <a class="footnote-reference" href="#light-theme" id="footnote-reference-6">[6]</a> minimalist page with a single menu on the
|
|
|
right containig all the relevant links. The page should not dictate too much
|
|
|
but rather let the user agent decide the rendering (<a class="reference external" href="https://html.spec.whatwg.org/multipage/rendering.html#rendering">it does anyway…</a>).</p>
|
|
|
<p>I want my blog to render similarly in Gecko-, WebKit- and Blink-based browsers
|
|
|
(e.g. Firefox, Badwolf, Qutebrowser). Others should be usable.
|
|
|
Browser-/engine-specific styles are not welcome – let's keep it simple. And no
|
|
|
JavaScript…</p>
|
|
|
</div>
|
|
|
<div class="section" id="work-in-progress-todos">
|
|
|
<h2>Work in progress / TODOs</h2>
|
|
|
<p>This thing is at the moment very barebones, which is sufficient for the main
|
|
|
purpose. However, I would like to have some features here, one day, hopefully:</p>
|
|
|
<ul class="simple">
|
|
|
<li>Dates in the article headers (and maybe more improvements of the theme, see
|
|
|
above)</li>
|
|
|
<li>Stable category and tag names and a page with a description of them. As of
|
|
|
now I haven't really invented a system of sorting my content, which leads to
|
|
|
a mess… Please don't rely on categories having any particular name / URL for
|
|
|
now.</li>
|
|
|
<li>Link the RSS feeds from somewhere</li>
|
|
|
<li>Personal info with links to my other profiles</li>
|
|
|
<li>Some linking to the Fediverse and using it for comments (since there will be
|
|
|
no comments here)</li>
|
|
|
<li>Sensible translations, maybe (if I/someone ever get to write the same content
|
|
|
again in a different language…)</li>
|
|
|
<li>Improve the list of talks I've given (create some kind of sensible table maybe?)</li>
|
|
|
<li>Decide on a licence for the content (If you want to utilize something here
|
|
|
before I do that, please ask me, I think we can find a way :-))</li>
|
|
|
</ul>
|
|
|
<p>If you are so upset with this blog (or maybe bored) that you want to improve
|
|
|
it, send me patches / ideas. I don't expect anyone to do that, though :-D (And
|
|
|
I do not promise you that I will use the patch, even if it matches all my
|
|
|
opinions above. I also have some gut feelings about what I like…)</p>
|
|
|
<p>Also, tell me if you hate something else about my page. I want to at least know
|
|
|
whom I upset :-D (but I will probably also think about your gripes and whether
|
|
|
I can and should try to avoid them…)</p>
|
|
|
<hr class="docutils" />
|
|
|
<table class="docutils footnote" frame="void" id="multiple-src" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-1">[1]</a></td><td>I also use multiple machines on which I can write stuff.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="skipping-stages" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-2">[2]</a></td><td><p class="first">I am lazy and chaotic (good), so the stages are optional
|
|
|
and non-linear, and sometimes involve paper. This article is a prime
|
|
|
example: parts of it were on two different private branches, but at the end
|
|
|
I wrote it from scratch directly on the main branch. And the requirements
|
|
|
were written on a paper originally.</p>
|
|
|
<p class="last">Nevertheless, the general idea still holds and may inspire others, so it
|
|
|
makes sense to keep this part in the article. (Also, this footnote might not
|
|
|
make sense before reading the definition of the stages, but I didn't find a
|
|
|
better place to put it…)</p>
|
|
|
</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="update-this" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-3">[3]</a></td><td>Well, given this article contains some future plans, I
|
|
|
actually anticipate update of this one, but maybe not in the near future. So
|
|
|
the outline is not really correct, but I make the rules :-) (There
|
|
|
were some build breaks on the main branch, too :-D)</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="private-branches-wish" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-4">[4]</a></td><td>I would love if my Forgejo could have &quot;private
|
|
|
branches&quot;, but I understand that the overhead for doing this is not nice,
|
|
|
since it would need to be able to decide for any object, whether it is
|
|
|
public or not (you can do <tt class="docutils literal">git fetch &lt;remote&gt; <span class="pre">&lt;object-hash&gt;</span></tt>) and somehow
|
|
|
keep track even with rebases, merges, force-pushes, many branches, … Having
|
|
|
a separate private repository is not a big problem in comparison.</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="git-purists" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-5">[5]</a></td><td>Git purists might want to tell me that committing build
|
|
|
artifacts is not good practice. I know and I explicitly don't care in case
|
|
|
of this repo, because here I prioritise my own comfort of being able to
|
|
|
check everything locally and then be reasonably sure the deployed version
|
|
|
will also work, all this with only a single push somewhere. Of course, one
|
|
|
could argue that with that there is no reason to create two commits, but it
|
|
|
does not really bother me to run something like <tt class="docutils literal">git commit <span class="pre">-m&quot;render&quot;</span>
|
|
|
output/</tt> when I am sure it works, and this keeps readable diffs separate
|
|
|
from the non-readable ones (i.e. the changes in generated HTML).</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
<table class="docutils footnote" frame="void" id="light-theme" rules="none">
|
|
|
<colgroup><col class="label" /><col /></colgroup>
|
|
|
<tbody valign="top">
|
|
|
<tr><td class="label"><a class="fn-backref" href="#footnote-reference-6">[6]</a></td><td>Having the page be dark-by-default is my preference, but I
|
|
|
respect that others may prefer light sites. However, I have not yet
|
|
|
determined what colors should be used (probably still cyan / blue / maybe
|
|
|
purple-ish, but I don't know what shade) nor understood how to use
|
|
|
<tt class="docutils literal"><span class="pre">&#64;media(prefers-color-scheme)</span></tt> in a maintainable and simple way (in the
|
|
|
context of my theme). So naturally, this is postponed to the future…</td></tr>
|
|
|
</tbody>
|
|
|
</table>
|
|
|
</div>
|
|
|
</content><category term="technology"></category><category term="meta"></category><category term="infrastructure"></category></entry><entry><title>Smršť 2023 (CZ)</title><link href="https://blog.ledoian.cz/smrst2023-cs.html" rel="alternate"></link><published>2023-12-02T18:00:00+01:00</published><updated>2023-12-02T18:00:00+01:00</updated><author><name>LEdoian</name></author><id>tag:blog.ledoian.cz,2023-12-02:/smrst2023-cs.html</id><content type="html"><p>Na <a class="reference external" href="https://ksp.mff.cuni.cz/akce/smrst/2023/">Smršti</a> jsem přednášel o distribuci SW a o technicky zajímavých železničních neštěstích.</p>
|
|
|
<div class="section" id="materialy">
|
|
|
<h2>Materiály</h2>
|
|
|
<ul class="simple">
|
|
|
<li><a class="reference external" href="https://blog.ledoian.cz/static/talks/smrst2023/talk.pdf">Slidy ke přednášce o neštěstích</a></li>
|
|
|
</ul>
|
|
|
<p>(Pozn.: Možná se ještě změní adresa téhle stránky, protože je to celé WIP…)</p>
|
|
|
</div>
|
|
|
</content><category term="talks"></category><category term="smršť"></category><category term="trains"></category><category term="software-engineering"></category></entry></feed> |