Linux on Nico Maas

labSentinel 2

Mon, 19 Sep 2022 09:35:01 +0000

About nearly a year ago, I wrote the labSentinel project for my Nvidia Jetson AI Specialist certification. The basic idea of the project is to be able to supervise old Lab Equipment which does not poses any kind of log output or interface other than a graphical user interface, running on an Windows 3.11 / 95 / NT - maybe even XP system.

I solved this issue by using a video grabber attached to a Jetson Nano and “out-of-band” grabbing the screen output of the experiment computer. I then learned good and bad system states via Nvidias Inference tools and finally got the system to report via MQTT as soon as something did go wrong.

WD My Cloud Mirror Gen2 with Debian 11 and Linux Kernel 5.15 LTS

Sun, 12 Jun 2022 18:05:32 +0000

Intro

Since 2017 I have been using an Western Digital My Cloud Mirror Gen 2 which I bought at Amazons Black Friday (or similar) - because the included 2x 8 TB WD Red were even cheaper with the NAS than standalone. Using the NAS had been quite ok, especially the included Docker Engine and Plex Support were a nice to have, the included Backdoor in older Versions - not so much. Recently WD had their new “My Cloud OS 5” replace the old My Cloud OS 3 - and made things worse for a lot of people. As I don’t want any more surprises - and more control over my hardware - I decided to finally go down the road and get Debian 11 with an LTS (5.15) Kernel running on the hardware. This is how it went.

fail2ban Cheat Sheet

Wed, 17 Feb 2021 10:22:00 +0000

Just the commands I always need to look up, because I forgot again…

Overview over fail2ban status and jails

fail2ban-client status

See which e.g. IPs are banned for sshd jail

fail2ban-client status sshd

Unban an IP from sshd jail

fail2ban-client set sshd unbanip IPADDRESSHERE

See which systems are actually banned

zgrep 'Ban' /var/log/fail2ban.log*

Bash for sending and receiving raw IP packets

Fri, 03 Apr 2020 07:35:12 +0000

I stumbled across this feature during my bachelor studies:

echo "Hello World" > /dev/tcp/127.0.0.1/5000
echo "Hello World" > /dev/udp/127.0.0.1/5000

You need to be root (obviously) and its supported in bash environment - but not on all systems. You can also cat on the ports and use dns adresses. Its neat to just get a byte out :). And if you need something more sophisicated, be sure to use the good old netcat (nc).

MacType - A better font rasterizer for Windows

Mon, 13 Feb 2017 13:00:24 +0000

If you’re tired of the ClearType Fonts in Windows and long for a more Unix/Mac Style Font Rasterizer, you most probably have heard GDI++ and GDIPP. And as both projects are somehow dead (for 6+ years), someone started a new one, called MacType.

How to install the latest version?

Download and Install MacType (chose English!): http://www.mactype.net/
Download the latest patch: http://silight.hatenablog.jp/entry/MacTypePatch currently the latest version is MacTypePatch_1.19.zip (2016/11/17).
Unpack the patch and copy EasyHK32.dll, EasyHK64.dll and UserParams.ini (from win8.1_or_later folder) to the C:\Program Files\MacType folder
Copy EasyHK32.dll, EasyHK64.dll to C:\Windows\System32
Start MacType as Tray Version and chose an default settings, i.e. FT Opt

Here you can see an example - left without, right with MacType:

Gitkraken - your next Git Client

Sat, 24 Dec 2016 15:00:28 +0000

If you’re in the NetOps/DevOps Teams, chances are high you need to develop code and use git. Well, on Windows Clients, I tended to use Atlassians Source Tree - however, that client became more and more buggy and unstable - unusable to say. Especially if I had to do an really big merge of my main to my deploy tag - it tended to crash most of the time.

So, without further ado: Enter Gitkranken. A nice, free, good looking and fast git client. Without dependencies.

[Linux] Delete old SSH Keys and recreate them

Sat, 14 Mar 2015 13:07:08 +0000

If you are downloading an Linux Image for i.e. Embedded Systems like Raspberry Pi, sometimes, the SSH Keys are still on the system and are not recreated.
To do that manually, just enter:

sudo rm /etc/ssh/ssh_host_*
sudo dpkg-reconfigure openssh-server
sudo service ssh restart

[Linux] Multiplexing Screen

Wed, 09 Mar 2011 07:40:03 +0000

And now an nice tip by Darren Kitchen of Hak5!
( www.hak5.org )

HakTip: Multiplexing Screen Sessions

What’s more wicked than a screen session? Two screen sessions! As we’ve talked about recently the unix command Screen is a great way to maintain bash sessions from multiple SSH clients without losing your work. My favorite shortcut after invoking the “screen” command is CTRL+a followed by “S”, which splits the screen horizontally in two. Use CTRL+a then Tab to switch between the views. Debian users get the added sexyness of vertical split by hitting CTRL+a then Pipe.

[Linux] Screen

Thu, 24 Feb 2011 17:12:50 +0000

Hello there, this a 5 Minute Tutorial to screen.
What Screen is?
Well screen is an old unix / linux terminal programm with which you can create multiple virtual “screens”.
You can switch between these screens and also can disconnect from them.
Especially useful: If you start an daemon within screen and disconnect from it,
you can reconnect anytime and see what its doing.
Or you can setup a screen session, detach and close your SSH.
If you reconnect, it will still be running.
Oh, and it will be also there and running if your connection drops.

Webconverger - Build your own Internetcafé

Tue, 22 Jun 2010 14:18:32 +0000

Install Debian
Add following lines to /etc/apt/sources.list :
deb http://live.debian.net/ sid-snapshots main contrib non-free deb-src http://live.debian.net/ sid-snapshots main contrib non-free
apt-get install live-helper git git-core svn sudo
mkdir /home/webconverger
cd /home/webconverger
git clone git://git.debian.org/git/debian-live/config-webc.git
modify /home/webconverger/config-webc/webconverger/auto/config
( i.e. change
homepage=http://portal.webconverger.com to the one you want,
add Kioskrest every 10 Minutes after last use:
kioskresetstation=10
change bootlogo
change website to the one you want and add an bg.png to the account,
otherwise add noxbg to the boot to make the background blank )
cd /home/webconverger/config-webc/webconverger
lh config
lh build
/home/webconverger/config-webc/webconverger/binary-hybrid.iso

Clean to rebuild:

Shrink VMware Image Files on Linux Appliances

Thu, 16 Jul 2009 13:35:19 +0000

Works only with dynamic HDDs!

Backup!
Remove old / unused Packages
Remove downloaded Packages: sudo apt-get clean, Remove only old downloaded Packages: sudo apt-get autoclean
“ZeroOut” unused Space: cat /dev/zero > zero.dat ; sync ; sleep 1 ; sync ; rm zero.dat
Under GUI: “sudo vmware-toolbox” and use shrink on “/”
Under VIClient: Defrag

Get Ethernetcard working again in Linux under ESXi

Thu, 16 Jul 2009 13:25:10 +0000

After installing Ubuntu Server on Vmware ESXi, I couldn’t find a NIC:

sudo /etc/init.d/networking restart

Reconfiguring network interfaces…

eth0: ERROR while getting interface flags: No such device  
SIOCSIFADDR: No such device  
eth0: ERROR while getting interface flags: No such device  
SIOCSIFNETMASK: No such device  
SIOCSIFBRDADDR: No such device  
eth0: ERROR while getting interface flags: No such device  
eth0: ERROR while getting interface flags: No such device  
Failed to bring up eth0.

Problem is that the ethernet MAC addresses are cached.

Install Vmware Tools on Linux

Thu, 16 Jul 2009 13:21:25 +0000

Under Debian necessary:

apt-get install autoconf automake make psmisc gcc  
apt-get install linux-headers-`uname -r` build-essential

Short:

tar -xzvf VMwareTools-######.tar.gz  
cd vmware-tools-distrib  
./vmware-install.pl  
vmware-tools-config.pl

Long:

Viclient, Connect to VM  
Menu "VM/Install VMware Tools"  
Tools are mounted to Cdrom  
mkdir /mnt/cdrom  
mount /dev/cdrom /mnt/cdrom  
cd /mnt/cdrom  
tar zxvf VMware-Tools-xxxxxx.tar.gz -C /opt/  
cd /opt/vmware-tools-distrib  
./vmware-install.pl