Screencasts on Ubuntu

For a colleague I just made a screencast of a problem we were discussing. I was trying to use the minimum amount of tools in Gnome/Ubuntu and wanted to share the proces with you all.

Goal: Create a screencast recording of my desktop with narrated (recorded) audio at the same time.

If you are very curious and want to see the result immediately, look at the video below:

“Apache Kafka files store data without encryption”

I use Pop!_OS 21.04, which is based of Ubuntu. In Pop!_OS I use Gnome with Wayland.
All the instructions below will work with Ubuntu and any Ubuntu based distribution as well.

This howto is divided in several sections:

  • Desktop (Video) recording
  • Audio recording
  • Putting the video and audio recording together

Additional tools used in the video:

  • Show the webcam (guvcview)
  • Written annotation on a page (xournal++)
  • Written annotation on screen (Draw On You Screen)

Video recording:

Since I want to use the most simple method, my approach is to use the built-in screen cast ability in Gnome.

Press Ctrl+Alt+R to start the screen cast recording.

When the recording is in progress, you see a red filled circle in your notification area:

When you press Ctrl+Alt+R again, the circle disappears and the recording is saved to the Videos folder in your home folder:

Note: This video file is without audio.

Audio recording

As the most simple solution I used the builtin Sound Recorder in Gnome:

Press “Record” to start your recording and click “Done” when you would like to end your recording. You can see me pressing the buttons in the recorded screen cast.

Important: You need to press the screencast start keyboard command Ctrl+Alt+R and the Record button at the same time, or your video and audio will be out of sync.

When you stop the recording, the Ogg Vorbis file will be saved in the default location in your home folder, which is: ~/Recordings.

Combine the video and audio

Right now you have two separate files, not really useful when they are not combined.

To combine them, I used the following command:

ffmpeg -y -i Videos/Screencast\ from\ 05-12-2021\ 02:51:06\ PM.webm -i Recordings/Clip\ 5 -map 0:v -map 1:a -c copy file.webm

Explanation of the command:

ffmpeg
 this is the command itself
-y
 overwrite output files without asking
-i {file location}
 input file + file location
 Note that there are two input files (video & audio)
-map
 Designate one or more input streams as a source for the output file. The number is the first (0) or second (1) input file. The map itself shows what we are using in the output. In this case it is 0:v to use the video for the first input file and 1:a to use the audio of the second input file
-c copy file.webm
 Specify the output file, in this case it will be copied to file.webm in the same directory as where you run the command.

The result is what happens here:

GIF recording of putting the video and audio together (Recorded with Peek GIF Recorder)

This is the minimum necessary to create a screencast!

For example, you can send this webm video output file to people over email / file share / whatever you’d like. You can also upload it to Youtube, which can process the output file and you are done to spread some knowledge!

Add some extra spice to your screencast

To add some engagement with whoever will view your screencast, you can show your own webcam in the screen. You can use the built in program Cheese

Another option is to use guvcview, which has a cleaner interface (no buttons on the webcam output window)

Install with sudo apt install guvcview , start the program with guvcview.

Then select your video input device. You can minimize the settings pane so that you’re left with only the video of your webcam for the introduction/conclusion of your video.

Annotation

For annotation I use Xournalpp (xournal++) which helps me in drawing with my XP-Pen drawing tablet. I think it makes the screen cast a bit more entertaining compared to showing plain text but you can decide for yourself.

You can also use a Gnome Extension called Draw on You Screen by Abakkk, with this extension you can do annotations directly on the screen and thus show your thoughts / comments / pointers on screen directly.

Note: I don’t use this extension in my example video though.

Conclusion

I hope this blog post helps you in creating screen casts with the simplest possible tools. Good luck and hope to see your videos around on the web!

Update HP Proliant Microserver BIOS without Windows

I wanted to update my MicroServer Gen8 bios to the latest version but the download site on HPE only showed .EXE files. Since I’m only running Linux on my machines it was not possible to execute that file.

You can however update the BIOS via ILO (Integrated Lights Out) if you extract the BIOS file from the executable.

First download the .EXE from the HPE site: https://support.hpe.com/hpsc/swd/public/detail?swItemId=MTX_e9bfdf20809a426cb16ef9cd81

(Currently the latest version is SP99427.exe. If you want to be sure you’re using the latest BIOS then click the tab “Revision History” to see if there are newer BIOS files available)

Extract the contents of the executable. Have a look at the directory structure below and extract the file marked "CPQJ06xx.xxx"(where “x” might change depending on versions)

.
├── How to Use.txt
├── logo.gif
├── README.1ST
├── rev_hist.txt
├── ROMPaq Flat Files
│   ├── CPQJ0613.684
│   ├── CPQSRVR2.CPU
│   ├── README.1ST
│   ├── Readme.txt
│   └── ROMPAQ.EXE
├── ROMPaq USB Key
│   ├── CPQJ0613.684
│   ├── CPQSRVR2.CPU
│   ├── HPEUSB.exe
│   ├── Readme.txt
│   └── ROMPAQ.EXE
├── Start_files
│   ├── colorschememapping.xml
│   ├── filelist.xml
│   └── themedata.thmx
└── Start.htm
3 directories, 18 files

Then log in to ILO and navigate to the page “Firmware” via the Menu Option “Administrator”

At the bottom of the page select “Browse” to select the CPQJ06 file and then click Upload.

Let the upload complete and reboot your Microserver. When you start the microserver it displays the BIOS version and date in the first line.

You can also see the version in the ILO overview page.

Citrix Receiver on Linux: SSL Error 61 ("You have not chosen to trust")

Important:
If you don’t know or understand certificates / root and intermediate certificate authorities, get someone who understands to follow below instructions.

I tried connecting to the company’s citrix server, but kept hitting the same error when I tried to open the connection:

Contact your help desk with the following information:
You have not chosen to trust "INSERT YOUR CA HERE",
the issuer of the server's security certificate (SSL Error 61)

It seems that Citrix has an alternate directory where it stores it’s trusted cert’s / certificate authorities. Even though you can see that the server’s certificate is trusted (by root CA’s) via a web browser, we need to copy those to the correct directory.
In short: Copy the root and intermediate CA’s to this directory: /opt/Citrix/ICAClient/keystore/cacerts
Continue reading “Citrix Receiver on Linux: SSL Error 61 ("You have not chosen to trust")”

Using SSH to forward the same local port to multiple external hosts

Okay, this is kinda awesome :-), I got my geek on 🙂
My application is connecting to a cluster of external servers but my application can configure hostname but can’t configure port.
So I wanted to connect to a remote cluster using SSH tunneling, but I was unable to forward everything because the port binding to localhost (127.0.0.1) can only be used once.
Then I saw that you can use multiple loopback addresses! See this page: https://en.wikipedia.org/wiki/Loopback
Basically you can bind the portforward to 127.0.0.2, 127.0.0.3 till 127.255.255.254, that should provide enough addresses, right!? 🙂
So I can use multiple port forwards from my localhost(s) to the six remote hosts like this:

ssh somedomain.com \
-L 127.0.0.1:9042:external-node1.somedomain.com:9042 \
-L 127.0.0.2:9042:external-node2.somedomain.com:9042 \
-L 127.0.0.3:9042:external-node3.somedomain.com:9042 \
-L 127.0.0.4:9042:external-node4.somedomain.com:9042 \
-L 127.0.0.5:9042:external-node5.somedomain.com:9042 \
-L 127.0.0.6:9042:external-node6.somedomain.com:9042

Vagrant proxy through CNTLM on Windows using CYGWIN

Wow, talk about a crappy post title, but I just got this working on my corporate network and was quite happy about it.
Reason for this post; Every time I start a new assignment at a (rather big) corporation, I need to follow these steps to be able to access the internet from my vm’s.
(and I keep forgetting the steps, I’m getting old..)
What we’ll use to get this working:

  • Cygwin : https://www.cygwin.com/
  • Vagrant : https://www.vagrantup.com/
  • Virtualbox : https://www.virtualbox.org/
  • Cntlm : http://cntlm.sourceforge.net/

I’m running CentOS vm’s inside Vagrant with Virtualbox provisioning on Cygwin on Windows 7. I’m running Cntlm to create a local proxy for all stuff what I’m doing through cygwin, because I don’t like putting clear text passwords in bashrc or in Win / Bash variables.

Steps:

  1. Get your corporate proxy URL (Via Google Chrome)
  2. Configure Cntlm
  3. Configure Cygwin
  4. Configure Vagrant
  5. Use teh interwebs from your VM, practicing ninja turtle coding skillz and be instantly awesome!!1!

Continue reading “Vagrant proxy through CNTLM on Windows using CYGWIN”

Python pip without internet

The title of this post is a bit misleading. I will not outline the use of pip without internet but I will suspect most people will search for this search string, thus coming here for an alternative.
I’ve been blessed with a very thorough security officer, who decided that CLI internet access is not permitted, even using CNTLM (1)is blocked.
The easiest way to install packages is via pip, but it’s also possible to install them via the commandline.
Using the example of Django, we will first download the tarball from the Django site;
https://www.djangoproject.com/download/
On the right side there’s a link to the latest release.
Unzip and untar the tarball and open a Prompt in that directory.
Then run the following command:
python setup.py install

Next, we’ll check if it is installed correctly:
2015-10-20 13_11_27-Opdrachtprompt

Comparing sed stream output in linux

Sed is very very powerful, which is a good thing to be aware of.
I was looking to compare the output of a sed command to the original file before I wanted to execute the sed command directly on the file and came across this handy trick.
It works by using temporary named pipes inside the diff command.
Contents of file:
[code title=”contents of numbers.txt:”]
One
Two
Three
Four
Five
[/code]
If I just want to remove the line which begins with “Four”, I can check my sed command like this:
[code title=”Terminal output:”]
joris@beanie ~
$ diff <(sed ‘/Four/d’ numbers.txt) numbers.txt
3a4
> Four
[/code]
Awesome possum, now I know my sed command won’t destroy anything.

SSH Remote Execute command, multiple command and with interaction

This article shows how to execute remote commands via ssh, but you’ll send the commands from your own shell.
[code highlight=”1″]
ssh my_server ‘ls -l /home/my_home_dir’
[/code]
This will result in this output:
[code highlight=”1″]
$ ssh ae2 ‘ls -lha ~’
total 36K
drwxr-xr-x 2 joris joris 4.0K Jan 23 11:42 .
drwxr-xr-x. 5 root root 4.0K Jan 23 11:41 ..
-rw-r–r– 1 joris joris 54 Jan 23 11:41 .bash_logout
-rw-r–r– 1 joris joris 507 Jan 23 11:41 .bash_profile
-rw-r–r– 1 joris joris 213 Jan 23 11:41 .bashrc
-rw——- 1 joris joris 51 Jan 23 11:42 .history
-rw-r–r– 1 joris joris 171 Jan 23 11:41 .kshrc
-rw-r–r– 1 joris joris 375 Jan 23 11:41 .profile
-rw-r–r– 1 joris joris 153 Jan 23 11:41 .vimrc
[/code]
What’s even better, is that you can run multiple commands separated with a semi colon, like this:
[code highlight=”1″]
ssh my_server ‘ls -l /home/my_home_dir;whoami’
[/code]
And the best trick is this one, user input with an interactive command, sending input and output back and forth!
[code highlight=”1″]
ssh -t my_server ‘vi ~/.bash_profile’
[/code]