blog.johanv.org (Posts about tips)

Working around a Pop!_OS networking issue

Johan Vervloet — Thu, 18 Nov 2021 18:01:00 GMT

Update (2021-11-26):

The solution I describe in the original post, did work for a while, and then stopped working. Then I got it working again by removing the kernel modules iwlmvm and iwlwifi, and modprobing iwlwifi again. Worked for a day, and stopped working again. So I guess it just sometimes worked, and sometimes, it didn't.

I think it was just the router. It's a TP-LINK TL-WR1043ND v2, and I installed OpenWrt on it (v19.something), a couple of years ago. Now I upgraded it to v 20.02.1, and I think - hope - that that will finally have solved the problem. I was a little reluctant to flash a firmware update, but it turned out to be very easy. The page for my device on the openWRT wiki had a direct link to the 'upgrade firmware', which I could easily flash using the openWRT web interface (using another device than my laptop, of course).

How to use a tablet as a third screen for your Ubuntu system

Johan Vervloet — Sat, 01 Sep 2018 20:22:14 GMT

At work I have a docking station, that allows me to use two external screens with my laptop. And I find this extremely useful. I put a terminal window here, some source doe there, a similar source file over there, and I need to write a unit test while looking up things on Stack Overflow. So those three screens are easily filled.

Sometimes I work from home. I don't have a docking station at my place, and I can use only one external screen. This works as well, but often I miss the extra screen real estate. We do have a tablet though, mainly used by our children. Those are typically away or asleep when I code... So how difficult could it be to use the tablet as an external screen?

Wireless networking on a Samsung Series 5 laptop with Linux Mint

Johan Vervloet — Mon, 17 Jun 2013 19:19:19 GMT

Wireless networking on a Samsung Series 5 laptop with Linux Mint

Last weekend, I installed Linux Mint 15 (Olivia) on a collegue's Samsung notebook. (I did a lshw, and it showed me '535U34C, Samsung SENS').

At my place, everything seemed to work OK (WPA2 and all), but when I tried it at work, the wireless connection dropped every x seconds, and needed to reauthenticate.

So I guess the problem depends on the type of wireless router.

I did some googling, and often I read that I had to pass the nohwcrypt=1 option to the ath9k kernel module. Which did not work. So I cluelessly tried some more suggestions, and finally I found a set of options that do work: nohwcrypt=1 blink=1 btcoex_enable=1 enable_diversity=1.

To try this out, you can do the following:

rmmod ath9k
modprobe ath9k nohwcrypt=1 blink=1 btcoex_enable=1 enable_diversity=1

(Maybe you have to log out and log on again after this command).

If it works, you can persist the settings, adding the following line to /etc/modprobe.d/ath9k.conf

options ath9k nohwcrypt=1 blink=1 btcoex_enable=1 enable_diversity=1

That worked for me. So I hope this information is useful for someone else as wel.

Many thanks to Sergei Winitzki, who posted the comment that saved my day.

Sending e-mail from mutt using an Exchange server

Johan Vervloet — Mon, 10 Jun 2013 18:01:51 GMT

My favourite mail client is mutt. At work we have an Exchange mail server, and I wanted to use mutt for my work e-mail. Today it works. (I am using Fedora 19 beta)

Our mail server supports IMAP access, so reading mail is easy. But the difficult part, is sending e-mails.

In a first attempt, I tried this in the mutt configuration:

set smtp_url="smtp://mylogin@our.local.mailserver:587"
set smtp_pass="mySecretPassword"

I think this has worked for me somewhere in the past, but now I get the error message 'No authenticators available.' So I had to try something else.

Now I am using msmtp to send my e-mails. I installed it from the repositories:

yum install msmtp

I created a configuration file: ~/.msmtprc:

account myaccount
host webmail.our.domain
from my.email@our.domain
auth ntlm
tls on
tls_trust_file /etc/ssl/certs/ca-bundle.crt
user mylogin
ntlmdomain MYDOMAIN
password "mySecretPassword"
port 587
account default : myaccount

In the mutt configuration, I removed the smtp-setttings, and added

set sendmail="/usr/bin/msmtp"

And guess what. It just worked (TM) :-)

Screencasts, Istanbul and Youtube

Johan Vervloet — Fri, 13 Apr 2012 08:19:23 GMT

Suppose you want to make a screencast, and upload the video to Youtube. This doesn't sound to hard to do. But I went through a lot of troubles before it actually worked. So I decided to write this down, in case someone else runs into the same problems. I am using Debian Sid.

There are several packages available for creating a screencast, and I first tried xvidcap. But when trying to record the sound as well, I got the message ‘Error accessing sound input from /dev/dsp’. I did some Googling, but I couldn't find an easy workaround.

So for my next attempt, I used Istanbul. This allowed me to create screencasts with sound, but when uploading the file to Youtube, Youtube complained about an unrecognized file format. Damn.

Again, if you Google the problem, you will find some tips, but none of them worked for me.

At last, after some trial and error, it seems that openshot can do the trick. Create a video project with openshot, import the ogg-video from Istanbul, put the video on the first track, and export the result again with the predefined web template. This creates a .mov-file, which youtube will happily show.

Fedora/NVidia font problem

Johan Vervloet — Tue, 01 Mar 2011 16:14:17 GMT

A quick fedora/nvidia tip:

After installing the evil and freedom hating nvidia-drivers on my Fedora system, a lot of font sizes magically increased. It seems you can fix this (per user) by clicking ‘System’, ‘Preferences’, ‘Appearance’. Click the ‘fonts’ tab, then the ‘details’ button, and change the resolution back to 96 dpi.

You can probably change this in some configuration file as well. If you know how, please let me know.

Filmpjes downloaden van Youtube

Johan Vervloet — Mon, 23 Nov 2009 19:31:13 GMT

Omdat dit enigszins valt onder veelgestelde vragen, is dit wel een blogpost waard. Hoe kan je filmpjes van Youtube downloaden, zodat je ze ook kan tonen als er geen internetverbinding meer is?

Je hebt twee dingen nodig.

1. Firefox. Firefox is een webbrowser, zoals Internet Explorer, maar dan anders. Als Firefox nog niet op je computer geïnstalleerd is, dan gebruik je waarschijnlijk Windows. Je dan hier een installatieprogramma downloaden, en het uitvoeren om Firefox te installeren.

2. De ‘Video DownloadHelper add-on’. Firefox is een uitbreidbare web browser, Video DownloadHelper is een uitbreiding van Firefox die toelaat om filmpjes van een webpagina als bestand te downloaden. Om het te installeren, surf je met Firefox naar https://addons.mozilla.org/en-US/firefox/addon/3006. Klik daar op de knop ‘Add to Firefox’. Het kan zijn dat er bovenaan een balk verschijnt, waarin je toestemming moet geven voor het downloaden van add-ons. Als dat gebeurd is, verschijnt er een ander kadertje, waarin je na 5 seconden op ‘Installeren’ kan klikken. Na de installatie zal Firefox voorstellen om zichzelf te herstarten. Klik op ‘Firefox herstarten’, en de installatie is rond. Bij de herstart van Firefox krijg je nog eens in een kadertje te zien dat de add-on geïnstalleerd is.

Als je nu naar een Youtubefilmpje surft (of eender welke webpagina met een filmpje erop), zal je naast de adresbalk het dansende icoontje van DownloadHelper zien. Naast dat icoontje staat een pijltje-omlaag. Als je daarop klikt, zie je de videobestanden die je kan downloaden. In het geval van Youtube zijn dat er meestal twee of drie. Geen idee waarom, maar meestal is het onderste bestand het meest bruikbaar. Klik dat dus aan, en de download zal beginnen.

Ik denk dat Firefox standaard naar je bureaublad downloadt. Maar als dat niet het geval is, kan je in het venster met de downloads rechts op de naam van het filmpje klikken, en vervolgens op ‘Map openen’