What is the size of a letter box?

The EN 13724:2002 “Postal services – Apertures of private letter boxes and letter plates – Requirements and test methods”, European standard for letterboxes specify that:

  • an envelope of C4 (229 mm × 324 mm) size must be deliverable without bending or damage;
  • the internal volume must able to hold at least a 40 mm high bundle of envelopes;
  • the height of an aperture is 30–35 mm;
  • the width of the aperture is either 230–280 mm (for C4 width) or 325–400 mm (for C4 height);
  • the mounting height of the aperture should be between 0,7 and 1,7 m.

Hacking LSS Chronolux

The “required insolation’ sector is added to support in-model decision on the limiting volumes and conditions.

This is not a public software, so please contact the author of the LSS Arch Tools for more questions.

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OpenSSL certificate generation

You must hae the CA configured properly, this no not the scope of this post.

For self-signed certificate

The self-signed certficate is in the <hostname>.crt, the private key is in the <hostname>.key

openssl req -x509 -newkey rsa:4096 -keyout <hostname>.key -out <hostname>.crt -days 365

For CSR (Client Certificate Request)

The request is in the <hostname>.csr, the private key is in the <hostname>.key.

-nodes option will turn off the password request, which is a Bad Idea for personal certificates and is sometimes used for server sertificates.

openssl req -newkey rsa:4096 -sha256 -nodes -out <hostname>.csr -outform PEM

mv mv privkey.pem <hostname>.pem

To generate a DH key

Make sure to adjust the Apache configuration accordingly, https://httpd.apache.org/docs/trunk/ssl/ssl_faq.html and https://raymii.org/s/tutorials/Strong_SSL_Security_On_Apache2.html

sudo openssl dhparam -out /etc/ssl/certs/dhparam.pem 2048

To sign a CSR

The request is in the <hostname>.csr, the signed certificates is in the <hostname>.crt.

openssl ca -policy signing_policy -extensions signing_req -out <hostname>.crt -infiles <hostname>.csr

To verify a certificate or request

The request is in the <hostname>.csr, the certificates is in the <hostname>.crt.

openssl x509 -in <hostname>.crt -text -noout
openssl req -text -noout -verify -in <hostname>.csr

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SSL, Postfix and IMAP

When setting up authenticated SMTP service, be sure your IMAP server is accessible. The reason for this is Postfix will check the username using SASLauth daemon. And SASLauth damon uses “rimap” method for checking the username. Rimap is “remote IMAP”, and it tries to log into the configured IMAP service, which by default is defined as ‘localhost’.

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Video distribution in the classroom

We have a computer room in our local university, ind it’s quite bussy. The main problem it became (this is another story) too long to be usable and there was a strong demand for the screencast view right on the student’s workplace. Yes we do use beamers, but the view was too small to dead the text on the screen.

And so the project was born. There is single seat where the view originates and multiple locations where it should be visible. The system must be easily expandable and upgradeable, no vendor lock-ins. All the points in the systems should be easily adjustable and replaceable.

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Small problem with CFD simulations

Just a tiny hole in the mesh may create a great mess.

The initial wind speed is 10 m/s, laminar aiflow. And the result is small F15+ class tornado int he Fujita scale.

Messing with PHP-ODT

I’m working oh hobby project on a free time, and one of the tasks here is to generate ODT file, containing output from the database. The output library i’ve chosen is PHP-ODT. It’s kind of basic, but allows to create ODT documents on the fly.

And now, lessons learned

Allways provide file size.

This code will create corrupt file, according to LibreOffice: The correct code is:

 header(“Content-Description: File Transfer”);
header(“Content-Type: application/vnd.oasis.opendocument.text”);
header(“Content-Disposition: attachment; filename=\”” . $ODTFile .”\”” );

 header(“Content-Description: File Transfer”);
header(“Content-Type: application/vnd.oasis.opendocument.text”);
header(‘Content-Length: ‘ . filesize($ODTtmpFile));
header(“Content-Disposition: attachment; filename=\”” . $ODTFile .”\”” );

It is possible to add hierarchical styles

Not in the base code yet

$pStyleDate = new ParagraphStyle(‘revDate’);

$pStyleDateStrike = new ParagraphStyle(‘revDate-strike’);

It is possible to add text decorations in the paragraph level

Again, not in the base code yet:


It is possible to merge cells in the table

Well, not in the base code and horizontally only:


$cRow = array($hSpan,$pRev,$pDate,$pMemo);

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My favourite X sceensaver is …


Captured with  ‘$ sleep 120 ; xwd -root -out full-screen.xwd


Replacement belt for Proxxon KS 230 table saw

The belt is B45MXL – MXL (0.08″) pitch, 45 -teeth, 10 mm width.

It will cost around $15 per 10 pack on if you know the pitch and length, or starting $15 for a single one, if you buy it as “KS 230 replacement belt”, part number  27006/57.


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The Power of Pipes

Okay guys, the log if filling with

sshd[20117]: Invalid user pi from port 50416
sshd[20117]: input_userauth_request: invalid user pi [preauth]
sshd[20117]: Received disconnect from port 50416:11: Bye Bye [preauth]
sshd[20117]: Disconnected from port 50416 [preauth]
sshd[20119]: Invalid user cubie from port 39772
sshd[20119]: input_userauth_request: invalid user cubie [preauth]
sshd[20119]: Received disconnect from port 39772:11: Bye Bye [preauth]
sshd[20119]: Disconnected from port 39772 [preauth]
sshd[20121]: Invalid user guest from port 42858

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