12volt DC Connectors on Narrowboat Papillon

What’s the best and most convenient connector for 12v appliances onboard?

The boat has some of these:

12v ‘Clipsal’ socket

They’re often called ‘Clipsal 12v’ sockets, (Clipsal makes a wide range of electrical gear); sometimes called a ‘2 pin parallel’ connector. I suspect they originate from caravanning. Note the neutral blade is wider than the live, for a polarised connection. Not to be confused with what I think is an older caravan 12v connector often called a ‘W4’, where the blades are the same size and angled:

12v ‘W4’ socket

Both of the above can handle 10amps. Other common 12v connectors found are the ubiquitous cigar/cigarette connector:

12v ‘Cigarette’ socket

Many 12v appliances come with a plug to fit they above. They’re not great connectors because they are an adaptation of the cigar lighter, and were not designed to be a DC connector.

I’ve also used a 12v ‘Hella’ plug (a nickname after the German brand that makes them). I first encountered this on our 1975 John Deere 2120. Hardly any tractors at that point had any kind of 12v outlet; it was probably fitted because the tractors were German made (Mannheim), where this connector is popular. It’s quite a good connector, but only 8amp (at 12v; can also be used for 24v)

‘Hella’ – aka Bosch, ‘BMW Accessory’ ‘Powerlet’, but properly ISO 4165

Proxmox VE 5.1 Setup Notes

Remove nag screen re: subscription: https://blog.briantruscott.com/how-to-remove-subscription-notification-from-proxmox-ve-5/

comment out the subscription repository. implement the ‘no-subscription’ repo instead.

guest vlan number works as expected.

To allow vm screen to be any resolution set the display properties in the vm settings to: https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=2ahUKEwjh5ZL8qJfmAhXLxYUKHcriC0YQjRx6BAgBEAQ&url=https%3A%2F%2Fpve.proxmox.com%2Fpve-docs%2Fpve-admin-guide.html&psig=AOvVaw2KNdlUnJ0XdafS2NLDLr7W&ust=1575388316614606

OpenLP throws error on startup with new installation on Xubuntu 18.04

markp@markp-OptiPlex-5040:~$ openlp
Traceback (most recent call last):
File "/usr/bin/openlp", line 27, in
from openlp.core.common import is_win, is_macosx
File "/usr/share/openlp/openlp/init__.py", line 26, in from openlp import core, plugins File "/usr/share/openlp/openlp/core/__init.py", line 43, in
from openlp.core.ui.mainwindow import MainWindow
File "/usr/share/openlp/openlp/core/ui/mainwindow.py", line 29, in
from distutils import dir_util
ImportError: cannot import name 'dir_util'

sudo apt install python3-distutils

system-config-samba

bit outdated in that the gksu command in the shortcut needs amending, but a very simple tool for creating smb shares that other can see. don’t forget to create users as well as define the windows shares. You need to:

sudo touch /etc/libuser.conf

.The gui shortcut can be made to work if you fiddle around and sort out gksu, but hardly worth the bother. Simply:

sudo system-config-samba

Drivers for AC1200MBS on xubuntu 18.04

promised my lovely ‘no wires in the new house’, so trying to get some 5ghz wifi sorted. Doesn’t work out the box. Try this:

sudo apt-get install rtl8812au-dkms

A previous dkms git install that used to work has ceased to (maybe with v5 kernel?). dkms status shows which modules installed this way and for which kernel:

markp@markp-ThinkCentre-M91p:~$ sudo dkms status
nvidia-340, 340.107, 5.0.0-23-generic, x86_64: installed
nvidia-340, 340.107, 5.0.0-32-generic, x86_64: installed
rtl8812au, 4.3.14, 5.0.0-32-generic, x86_64: installed

This command will remove the above to ensure clean system for next attempt:

sudo dkms remove rtl8812au/4.3.14 --all

Backing Up using cron and rsync

The rsync script for this is in /home/markp/Documents/scripts: rsync-shell.sh
it creates a log file in /home/markp/Documents/backups
it backs up to an external e-sata hdd mounted at /external in fstab
it needs to be copied to /root so that it can run as a sudo cron jon
ensure chmod 744 so file is executable

in root, crontab -l lists all cron jobs; if no crontab exists yet create one with:

sudo crontab -e 

then add:
0 2 * * * /root/rsync-shell.sh

the five cron parameters above are:
minute (of the hour)
hour (of the day)
day (of the month)
month
day (of the week)
* = any value. So, the above job runs every day at 2.00 (am).

Issues: need to find a way of flagging when the cronjob doesn’t run, although the log reveals that. 2. need to find a way of bringing the PC out of suspend, now that I’m trying to be more power saving.

For 2. see here: https://www.dedoimedo.com/computers/wake-cron.html

LTSP Public Lab – 2019

LTSP has the ability to offer thin or fat clients which boot from a centrally controlled image from a server using tftp network boot.

The following guide uses Xubuntu 18.04 (LTS desktop 64bit version), using a ‘chrootless’ (aka PNP ltsp) setup, which unlike the more common chroot-ed ltsp setups, uses the configuration of the server’s desktop to create the image the clients will boot from. The reason for not doing this in the past was related to the DHCP setups for such networks, but dnsmasq used in conjunction with a separate dhcp server makes for a simpler setup, as long as using the server’s desktop to create the client desktop is not an issue. With a chroot setup (my first attempt) a server can have no gui and multiple desktop environments can be deployed, independently of how the server is setup, if required. I found it more complex to administer and the script for resetting the clients upon each boot I found never worked.

The following is based on this guide, which in my opinion breathes new life into ltsp after what looked to me like it not being developed much recently. For those wanting to create public lab/ICT suite setups on a budget there is still much to be gained from using this approach, especially when combined with the possibilities that Dashamir Hoxha suggests. LTSP can offer normal user accounts for many users, but in the public lab situation clients that auto login and then reset themselves clean upon logging out is a real administrative boon. All the clients have a single point of control: updating, maintaining and adding new software for the lab is done once on the server using a template ‘guest’ account. This creates the settings for the all the individual client accounts to clone when they boot.

Create a clean Xubuntu 18.04 server

apt install --yes synaptic

add-apt-repository --yes ppa:ts.sch.gr

apt update

Choose the ‘chrootless’ option

apt install --yes --install-recommends ltsp-server-standalone ltsp-client epoptes
gpasswd -a ${SUDO_USER:-$USER} epoptes
ltsp-update-image --cleanup /

Choose the single NIC option

ltsp-config dnsmasq

Create the lts.conf

ltsp-config lts.conf

Auto-create ‘guest’ accounts using Dashmar’s script: https://gitlab.com/Virtual-LTSP/VirtualBox/blob/bionic/scripts/create-guest-accounts.sh

Suggested location for the creation of this file: /usr/local/bin Then: chmod 0700 create-guest-accounts.sh and execute the file (as root) from within that folder with: ./create-guest-accounts.sh

This creates 254 users: ltsp1 – ltsp254. These user accounts will be allocated per client machine based on the IP address given to each client by (in my case) the pfSense DHCP server. ie 192.168.14.100 will login with user ltsp100 . Nb. in pfSense DHCP server must be running for the ‘LTSP’ subnet, and the Ignore BOOTP queries option must be checked, becasue the LTSP server must respond to the bootp queries.

The script also does a number of other things: it creates a user called ‘guest’ which acts as a template master for all the client guest accounts. Any changes to the configuration of that account/desktop are replicated to all the ‘ltspxxx’ accounts. When those accounts logout they are reset to the guest account template each time (brill), means all the usual detritus of people logging in and using a pc is eliminated. Serious kudos to Dashamir Hoxha for this work. Strangely I had thought that this setup would be ltsp default, but it’s taken some time to find the solution and deploy it.

Adding:

[Default] 
LDM_GUESTLOGIN=True[00:25:64:e6:b5:0a]
LDM_AUTOLOGIN = True
LDM_USERNAME = wesleyonline1
LDM_PASSWORD = wesley

to the lts.conf file, (on the chrootless setup it’s at /var/lib/tftpboot/ltsp/amd64/lts.conf ) adds a ‘Login as Guest’ button to the LTSP client login screen. Ideal for very large deployments. In my smaller lab I’ve edited the lts.conf file adding:

[00:25:64:e6:b5:0a]
LDM_AUTOLOGIN = True
LDM_USERNAME = ltsp100
LDM_PASSWORD = ltsp100

… for each pc. This is allows clients, per mac address, to be automatically logged in with a particular account number. In our context we are often dealing with people who have never used a PC before, so not requiring them to use a username and password as the first thing they have to do is advantageous.

Issue re: “Configured directory for incoming files does not exist Please make sure that directory “/home/guest/Downloads” exists or configure it with blueman-services”

remove the applications related with bluetooth because the ltsp123 client accounts cannot access the absolute path from the template ‘guest’ account. On the xfce desktop the ‘Application Autostart’ list is found in the ‘Session and Startup’ section of Settings Manager. Remove the ‘Blueman Applet (Blueman Bluetooth manager)’ on your guest template account from this list.

Ubuntu and the XFCE desktop which Xubuntu uses is usually not greeted with the excitement I get when logging into it. ‘Oh it’s not windows’ is often the fearful or dissapointed reaction. Users have soon realised that navigating a slightly different desktop isn’t as hard as they might have thought – not as hard as adapting to Windows 10 in my experience, however, to make things less fearful I have ‘made it look like windows’ (a bit!)

There are several places to get themes and icon sets to make the xfce desktop environment look a bit like windoze. I have used boomerang (google for it). To make them available (for all users) on a pc add the theme folder to: /usr/share/themes . Add the icons to /usr/share/icons . Add the win10 wall paper to /usr/share/xfce/backdrops/ ensure the file has permission set: 0644

You might need to create the icon cache: sudo gtk-update-icon-cache /usr/share/icons/Windows-10-Icons/

Printer:

To get the Xerox printer working with the LTSP clients use CUPS. This connects using ipps. On the guest login (template master) browse to: localhost:631 and the CUPS admin page appears. Although the Xerox C405 might be listed, I’ve had better success with adding the printer as a new one (couldn’t share the automatically detected ones); no need to install drivers for an ipp printer (which prints using http). Within the control webpage go to: Administration and choose: ‘Share printers connected to this system’ this allows the client PCs to see the printer. Only a sudo account can authorise these changes, not the guest account itself.