Ondřej Caletka

Technical expert at RIPE NCC Learning and Development. Interested in open source software, the Internet and public transportation.

Personal website: https://ondřej.caletka.cz
Blog: https://ondřej.v.nizozemsku.nl

Last Notes

2026-06-02 08:53:59 GMT

Nikdy jsem aktivně neinstaloval blokovače reklam. Opravdové reklamy mi vlastně ani tolik nevadí. Nevadí mi ani nabídky na evidentně falešné zboží.
Pokud se ale rodičům zobrazuje pod videem na YouTube nebo mezi jízdními řády reklamní banner imitující systémový dialog, obsahující varování že „prohlížeč PDF je zastaralý a je potřeba ho aktualizovat,“ začíná mi s reklamou docházet trpělivost.
#malwaretising

2026-04-28 08:52:37 GMT

Už jen dva dny zbývají pro přihlašování přednášek na #DenIPv6, který se letos koná 4. června 2026
https://denipv6.cz/cs/#prednasky
https://files.mastodon.social/media_attachments/files/116/481/467/015/103/710/original/887e6578b42a9b7c.gif

2026-03-05 10:10:51 GMT

TIL: There is a book called "Unicode," which encodes standard life situations into rarely used latin words so you can save money on telegrams that are charged per word.
https://archive.org/details/unicodeuniversa00unkngoog/page/n35/mode/2up
https://files.mastodon.social/media_attachments/files/116/176/021/489/079/988/original/063da1eb41523ff3.png

2025-11-17 15:51:33 GMT

Them: please make sure your name is the same as on your ID card. Pay attention to diacritics like é, ë, ß or œ.
Me: fixed my name to Ondřej
Them: only letters and dashes are allowed. 🙄🤡
#Rabobank
https://files.mastodon.social/media_attachments/files/115/565/824/907/750/485/original/2b43fefe23307426.jpg
https://files.mastodon.social/media_attachments/files/115/565/826/101/620/569/original/0a6344688a1cbb03.jpg

2025-10-18 06:14:11 GMT

- reply

sure, it is linked in the yellow field of the draft: https://github.com/oskar456/ietf-aaaa-filtering
(I cannot seem to be able to add the link to the Datatracker page of the WG document)

2025-10-17 18:18:49 GMT

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We just got the same news yesterday: https://support.okta.com/help/s/article/upcoming-ipv6-enablement-for-the-okta-cdn?language=en_US
Hopefully it will work well. But other than that, there's nothing much to talk about. Except that I'm trying to fix the other issue in the IETF:
https://datatracker.ietf.org/doc/draft-ietf-v6ops-aaaa-filtering/
@npub1srq…rkt8 @npub1a94…n8hn

2025-07-30 20:09:28 GMT

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option 108 with value of 0 🤔
That does not look right 😮
> MIN_V6ONLY_WAIT:
> The lower boundary for V6ONLY_WAIT. Value: 300 seconds

2025-05-16 10:36:17 GMT

The most important presentation of #RIPE90 is going to start soon: RIPE 90 Technical Report.
https://ripe90.ripe.net/programme/meeting-plan/plenary/#fri2

2025-04-14 08:49:08 GMT

Už jen pár posledních dnů je možné přihlásit přednášku na letošní Den #IPv6, který se uskuteční v tradičním termínu 6. června 2025 v NTK v Praze.
https://denipv6.cz/cs/

2025-04-02 07:39:58 GMT

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Oh, is there IPvFoo for Android?

2025-02-24 08:44:21 GMT

„For more than 20 years, we’ve been buying nothing else; our own industry has withered. We regret that the local baker, butcher, and poulterer have disappeared from the shopping street. But we never bought anything from them anymore, so it’s our own fault.“ - [@bert_hubert](https://fosstodon.org/@bert_hubert )
#cloud
https://berthub.eu/articles/posts/communicating-without-musk-and-trump-cloud-kootwijk/

2025-01-31 09:45:28 GMT

Also, who would have expected that when travelling between Amsterdam and Paris, one needs to bring a BS 1363 socket adapter.
Half of the seats is equipped with Schuko sockets though so this is a matter of luck.
https://files.mastodon.social/media_attachments/files/113/922/313/741/028/355/original/b1a1a29464ecfe18.jpg