Linux related stuff

Bandwidth monitoring

Useful console programs

To install them all:

sudo apt install bwm-ng iftop nethogs nload

Useful gui programs

SSH load key error in libcrypto

Occasionally on Ubuntu 22.04 I've experienced the error message shown below when trying to connect to a server using an ssh key:

$ ssh -i ~/.ssh/id_ed25519 
Load key "id_ed25519": error in libcrypto

I finally realized the problem was the presence of DOS style CRLF end of line designators. Using dos2unix to convert the end of line designators resolved the issue.

$ dos2unix ~/.ssh/id_ed25519


Useful system commands


# Show maximum capacity and number of RAM slots
sudo dmidecode -t 16
# Show information on RAM in slots
sudo dmidecode -t 17

# Shows all memory related information in the system. Slow as it polls all hardware first.
sudo lshw -class memory

VBAN for Linux

I've used Voicemeeter Banana and Potato for a long time to do advanced audio management on my various computers, including streaming audio from various computers in the house to my laptop and vice versa.

VBAN for Linux allows me to incorporate some older laptops (that have trouble running Windows but no problem running Ubuntu Desktop) into my various setups. Primarily I use a second laptop to stream Youtube or Udemy videos while I'm using my primary Windows laptop. Bluetooth headset is connected to the primary laptop and all other audio sources are sinked to it. 👍

Configuring Ubuntu 20.04 to sink audio and use vban_emitter to stream to a VBAN receiver

Preparing Pulseaudio

pactl load-module module-null-sink sink_name=vbanmix

# use "pactl info" or "pactl list" to find the proper alsa_output interface
pactl load-module module-combine-sink channels=2 slaves=vbanmix,alsa_output.pci-0000_00_1b.0.analog-stereo

pactl set-default-source vbanmix.monitor


Running vban_emitter



vban_emitter --ipaddress=$IPADDR --port=$UDPPORT --streamname=$STREAMNAME --backend=$AUDIOBACKEND --rate=$SAMPLERATE

Running on a headless system

After banging my head against the wall for weeks trying to figure out how to get vban_emitter working on a Raspberry Pi and an f80a, here's what I found.

By default, Pulseaudio only works with a user logged in directly to the system. After trying to get Pulseaudio setup to run in system mode, I realized it's much easier to just leverage ALSA directly.

The default ALSA configuration is set to use CARD 0. When using USB devices, these are inserted as CARD 1. In order to use this, you need to either update or create the /etc/asound.conf file with the information below:

# /etc/asound.conf
defaults.pcm.card 1
defaults.ctl.card 1

Here's the vban_emitter command to use:

vban_emitter -i IP_ADDRESS -p 6789 -s STREAM_NAME -b alsa