Spinning Up Ubuntu 16.04 on a VPS instance

  • Create keys for SSH (in this case on linux command-line)
    ssh-keygen -t rsa
  • Name server hostname (I used these instructions (archive) for hostname)
  • Set reverse DNS in VPS server console equal to FQDN
  • Change SSH port & disable password authentication with
    sudo nano "/etc/ssh/sshd_config"
    then restart ssh
    sudo systemctl restart ssh
  • create non root user, copy .ssh folder from root to their profile, making sure to chown newuser for the authorized_keys file, and add the user to group sudo – sudo addgroup groupname.
  • Add auto security updates.
    sudo apt-get install unattended-upgrades
    sudo dpkg-reconfigure unattended-upgrades
    sudo nano /etc/apt/apt.conf.d/50unattended-upgrades **requires root email for notifications*
  • Set time zone
    sudo dpkg-reconfigure tzdata

Duty Cycle Protector

I have a solar pool pump inline with a normal pool filter pump. If the pool pump turns off while the solar pump is on.. then the solar pump can’t pump properly. This is an issue since the filter pump sometimes will turn off in hot weather (or if hot water is flowing through it). I built a sensor to require the filter pump to run in order to run the solar pump. Also I ran an external switch for the solar pump.

I will note that working with mains voltages is inherently dangerous, and I’d advise against it for anyone not sufficiently trained.

The circuit consists of a current sensing board ($5.50 with delivery) and a Zero-Cross SSR ($12 delivered…). The sensor is just a coil around one of the conductors in a ‘sensor’ mains extension cable. When current is high enough through the sensor, the SSR is in turn energised, closing the circuit through a second ‘trigger’ extension cable . I put a switch in between the sense output and the SSR. That’s basically it. I thought about a pull-down resistor on the input for the SSR, but since it needs 5v plus a small current to trigger.. I think it should be fine left open.

Initially I used a current sense board with no relay output, although this did not live up to specs delivering 5v digital output and caused a bunch of issues… eventually I gave up trying to implement a transistor/relay and bought a sense board with an inbuilt relay. The components in the system run off 5v and are powered by a USB power adaptor 🙂

It Works!

OpenVPN for Mikrotik client

From this setup for OpenVPN Server on Ubuntu 16.04..

We need to unbolt some of the security features of the server config for Mikrotik compatibility.

I guess this isn’t explained in bright colours on their wiki examples cos they’re not proud of not being up with latest crypto. Which is more annoying cos it took a day, where as getting the server online took 20 minutes on a digital ocean instructional.

Continue reading “OpenVPN for Mikrotik client”

OpenVPN Server on Ubuntu 16.04

Following this guide.

NOTE 1: In the part where they edit /etc/openvpn/server.conf

I edited the server directive to read:
server 192.168.155.0 255.255.255.0

then my UFW rules are

# START OPENVPN RULES
# NAT table rules
*nat
:POSTROUTING ACCEPT [0:0]
# Allow traffic from OpenVPN client to ens3 (change to the interface you discovered!)
-A POSTROUTING -s 192.168.155.0/24 -o ens3 -j MASQUERADE
COMMIT
# END OPENVPN RULES
Continue reading “OpenVPN Server on Ubuntu 16.04”

SAP – refocusing

The Lawnmower Man (1992)
Still from The Lawnmower Man (1992)

It’s been too long since I put some time into this project, so I’m going to outline goals broadly and then narrow into smaller components.

Goals:

  1. Enumerate SIM software options, noting:
    -DK2 compatibility, Retail rift (CV1) compatibility (which has many moderate advantages over DK2), environmental data output capabilities, associated existing environmental data hardware.
  2. Enumerate environmental data hardware options. Most all options are for motion platforms, will these work for my full 3D system?
  3. Options for motion actuation, look into various high torque motor options. Variables include torque, rotation accuracy, rotation speed, control interface and compatibility with environmental data hardware.
  4. Physical design. Design different styles, noting size requirements, mass, portability, aesthetics, structural design and stress tolerance calculations. Construction may need some legal/insurance considerations.

Steps 1-3 represent the bulk of the electronic challenges. Step 4 is the physical challenge Continue reading “SAP – refocusing”

Beaumast Part 2

The main challenge installing guy wires onto a tiled roof was how to make anchor points. I went to a local antenna supplier and they told me the usual method is with these long self tapping o-ring bolts. So that’s what I did, it was much easier than I expected.

I used a diamond hole saw from eBay to make 2 holes in the roof tiles, and made use of an existing satellite dish mast for the final mounting point. I used threaded rod to attach a tapped o ring (or whatever you call it) to the satellite mast. Using a wet finger I was able to mold silicon around the anchor bolts in the roof tiles.

Part 1 ->

From my understanding it’s better to be earthed than not… I tried running conduit through this cement path using only an angle grinder and a chisel. This would have taken waay too long. Ended up buying a jack-hammer from gumtree (cheaper than renting). The second earth wire is from a UBNT Ethernet protector in the roof-space. This goes to a separate earth rod a small distance from the mast earth rod.