Tag Archives: raspberry pi

Domoticz part 5: Grafana, InfluxDB, Telegraf – beautiful and easy graphs

Grafana is the answer to the nagging question we’be been asking ourselves over the years – how to quickly and nicely present our data gathered from devices. InfluxDB on the other hand is the database that is as easy and simple to use, thus making it an ideal candidate for this job.
Let me show you how to quickly and easily put our data from domoticz and other devices to InfluxDB and then using Grafana – display in much more useful way than default domoticz graphs do.

What will we need?


  • InfluxDB
  • Grafana
  • bash scripts


  • Raspberry Pi – 4B+
  • OPTION: Raspberry Pi A/B/B+ lub Zero (armv6)
  • OPTION: A different ARM based micro-computer (i.e.: OPi PC” rel=”noopener” target=”_blank”>Official Store – OrangePi PC using CPU H3/H2/H5) – they could be cheaper. It’s also entirely possible to use x86 computer with Debianem, but it’s going to eat way more than 4-6W when using ARM based. Here I used finally Orange Pi PC with latest armbian distribution, tested first on latest Raspberry Pi 2

Continue reading Domoticz part 5: Grafana, InfluxDB, Telegraf – beautiful and easy graphs

0.96″ OLED SSD1306 display and Raspberry Pi

[Update: 2019-03-30] Our reader, Paweł Kopacz, noticed that pip, setuptools and wheel are also needed
Quick and visually compelling projects don’t come easy ? Naaah, just like last time – let’s get on a very nice and easy project – attaching display onto Raspberry Pi. As we were chating on the Malinowe Pi Group, Hubert Wu pointed me to a OLED 128×64 display, monochrome. With a quite decent resolution of 128×64 and based on OLED technology this is a nice 0.96 inch display. Well, my first computer was running at Hi-Res of 640×400 and monochrome too. Priced at $3-$5 pops-up as: ”0.96″ I2C IIC Serial 128X64” in popular stores and is clearly based on original Adafruit SSD1306 – which would be my first choice!

Wyświetlacz OLED SSD1306 - grafika
A OLED SSD1306 display

Continue reading 0.96″ OLED SSD1306 display and Raspberry Pi

[UPDATED 03-02-2018] SMOG sensor – 2,5 and 10 micro meter particles

[Last changes]:
07-11-2017: Additional data from richer stations, Open-Smog Integration
20-12-2017: USB power control on Raspberry Pi 3, thanks to reader
02-03-2018: New API from GIOŚ Poland

SMOG is common nowadays in big cities. Let’s put together a working, precise own SMOG sensor, first for the 2,5 and 10 μm size particles. There is one issue – the choices are many, but only few are reliable, precise and have affordable price. Finally – after a log searching, I’ve chosen Nova Fitness SDS011:

  • precision is OK
  • fan included
  • ability to mount a small tube to access external air
  • very realiable
  • UART with USB converter included
  • Low Total cost: around $40 (with Orange Pi Zero) up to $60 (with Raspberry Pi)

Continue reading [UPDATED 03-02-2018] SMOG sensor – 2,5 and 10 micro meter particles

Domoticz part 8 – Stable instance of Domoticz, 24/7/365 mode – high availability at home

As a result, a both fresh and advanced user finds himself in a situation where the system – ceases to work at all, or requires frequent restarts, or worse causes quick degradation of the main storage device – which is often (micro) SD card.

Is there a simple and effective solution to increase Domoticz’s availability on Raspberry Pi / Orange Pi?

Sure there is! But first – before you begin – make a copy of your (micro)SD working used in domoticz instance on your Raspberry Pi/Orange Pi.
CAUTION: We will perform operations that may lead to the loss of all data – so make sure you have a copy!

What will you need?


  • monit
  • rsync


  • harddrive either classic HDD or better SSD, small is OK from 32GB up to 128GB
  • heatsinks for Raspberry Pi/Orange Pi
  • USB 2.0 or 3.0 to SATA adapter – so we can connect the harddrive via USB port

Continue reading Domoticz part 8 – Stable instance of Domoticz, 24/7/365 mode – high availability at home

OpenVPN Raspberry Pi – split-tunnel with Internet access

Would you like to connect from any place, usually using open WiFi network in town, at friends or airport – with your’re own home network? Virtual Private Network (VPN) is here to allow you to log-in securely to your home network, with additional perk of using it to get secure Internet access.

Raspberyy Pi B+
Raspberyy Pi B+

What will you need?


  • Rapberry Pi (A, A+ or B, B+, 2, Zero)
  • Home Router with Port Forwarding or Virtual Server support – any will do


  • Raspbian – standard Linux distribution for Raspberry Pi
  • OpenVPN – free OpenVPN server
  • OpenVPN – clients – different for Linux, Android, MS Windows etc.

As you see nothing fancy.


Let’s talk about how we should secure our access:

  • physical access to your Raspberry Pi should be controlled (only you)
  • access to /etc should be restricted to the user that OpenVPN is running under
  • the files with .key are TOTALLY SECRET
  • the certificate .crt or .crs – are to be sent, lost, revoked – could be always renewed.
  • each device connecting to OpenVPN server (PC, tablet, smartphone) has it’s own key/certificate pair

Let’s do it

Well, as always the first thing is to update out RPi – let’s login via ssh or console:

sudo apt-get update && sudo apt-get upgrade

Now, lets install OpenVPN package:
sudo apt-get install openvpn

All commands used require root privileges, so I suggest to enter:
sudo su -

Next we should configure the server, first to generate SSL certificates, that allow securing of the connection and also – authentication.
All files should be stored in /etc, let’s create appropriate folder and copy over the example files to create certs, which reside in Raspbianie Wheezy here:
cd /etc/openvpn
mkdir easy-rsa
cp -R /usr/share/doc/openvpn/examples/easy-rsa/2.0/* easy-rsa/

If you’re on the newer Jessie, as noted in comments by Dom/OloX – folder with examples is located in /usr/share:
cd /etc/openvpn
mkdir easy-rsa
cp -R /usr/share/easy-rsa/* /etc/openvpn/easy-rsa/

Examples provided by easy-rsa package default to USA based data. Wait, what ? It’s all about the fact that the certificate has to have identification – who’s the authority that issued it. Since it’s going to be ours – we should put some familiar data here to identify it later.

Let’s edit the file ( or accept the fact that all certificates are from San Francisco…):

sudo nano /etc/openvpn/easy-rsa/vars

The changes are about the folder where we store the certs and keys, length of the asymetrical key – it’s usually1024 – but 2048 might be too much from RPi 1, or even 2 or 3. Let’s use the value of 1024:
export EASY_RSA=”/etc/openvpn/easy-rsa”
export KEY_SIZE=1024
export KEY_CITY="SanFrancisco"
export KEY_ORG="Fort-Funston"
export KEY_CN=SerwerOVPN

Country code – PL,  county/voivodeship: WA and so on – use what you like or don’t, but the KEY_CN – this should be changed.
Let’s prepare to create the keys:
cd /etc/openvpn/easy-rsa
touch keys/index.txt
echo 01 > keys/serial
. ./vars  # set environment variables

Now we will build a certificate authority::

All you need to do is to confirm values previously entered in vars:
Generating a 1024 bit RSA private key
writing new private key to 'ca.key'
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
Country Name (2 letter code) [PL]

The folder keys will now have ca.key and ca.cert.

Now, important port – generating the key to our system:

./build-key-server server

We will be asked to provide password. STOP. OK, enter a password – but then you will also have to enter it with each connection. We can remove the password and lower our security – the choice is yours!
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:

Answer yes to remaining questions and you will get in folder keys new files: server.crt and server.key in (/etc/openvpn/easy-rsa/keys/), they will be signed with your root certificate.
Now let’s build the Diffie-Hellmann parameters required for client and server to talk to each other. The process is quite interesting – check out  https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange 

This produces 1024.pem file, change the name to dh1024.pem
Now lets build the pairs – files – for a client:
./build-key client1

…along with the password:
./build-key-pass client1

That’s nearly the end – now let’s generate common HMAC key for TLS:
openvpn --genkey --secret /etc/openvpn/easy-rsa/keys/tls.key

Let’s copy all the files /etc/openvpn/mykeys/
cd /etc/openvpn/easy-rsa/keys
mkdir -p /etc/openvpn/mykeys
cp dh1024.pem /etc/openvpn/mojeklucze
cp ca.crt /etc/openvpn/mojeklucze
cp server.crt /etc/openvpn/mojeklucze
cp server.key /etc/openvpn/mojeklucze
cp tls.key /etc/openvpn/mojeklucze

It’s time to configure our OpenVPN server using certificates and keys.
First create the /etc/openvpn/openvpn.conf file with following entries:
push "redirect-gateway"
push "dhcp-option DNS"
push "dhcp-option DNS"
dev tun
verb 5
proto udp
keepalive 10 120
port 1194
dh /etc/openvpn/mykeys/dh1024.pem
ca /etc/openvpn/mykeys/ca.crt
cert /etc/openvpn/mykeys/server.crt
key /etc/openvpn/mykeys/server.key

user nobody
group nogroup

status /var/log/openvpn-status.log
verb 3
log-append /var/log/openvpn

The configuration of the server will get all the traffic coming from it (apart from static routes on the client – accessing the other LAN) and steer it to tunnel. Thanks to this we will also have Internet access through our tunnel and VPN (but check below!). The resolvers for DNS operation – let’s use Google and our local as secondary. The important line is ‘server’ this creates a network used only for the actual connection – so use private network you don’t use anywhere. The port is 1194 – we will have to reconfigure our home router for connection – see below for Port Forwading options. The protocol used is UDP.

Port forwarding

The forwarding of the public port from your router to private port on Raspberry Pi is quite easy to configure:

Port Forwarding - Linksys
Port Forwarding – Linksys
Port Forwarding - D-Link DIR
Port Forwarding – D-Link DIR
Port Forwarding - Archer VR900
Port Forwarding – Archer VR900
Port Forwarding - TP-Link
Port Forwarding – TP-Link
Port Forwarding - TP-Link
Port Forwarding – TP-Link

Split-tunnel – safe access to Internet by means of VPN

To allow split-tunnel – we need to add configuration at the end of the /etc/rc.local file.
Do mind that you need to change the example RPi address of to yours, and as mentioned above – choose unused VPN – here:

The file should have following lines:

echo "Enabling routing for proper VPN operation..."
echo 1 > /proc/sys/net/ipv4/ip_forward
echo "Remote port mapping for VPN service..."
iptables -t nat -A INPUT -i eth0 -p udp -m udp --dport 1194 -j ACCEPT
echo "SNAT of the VPN addresses to allow split-tunneling..."
iptables -t nat -A POSTROUTING -s -o eth0 -j SNAT --to-source

exit 0


Let’s configure the client – first mobile devices – Android. Download the OpenVPN (check for fakes!) and after installing – it’s going to ask for .ovpn file. Let’s create it, don’t forget to change the IP_ADDRESS_OR_FQDN_OF_THE_SERVER to your OpenVPN server.

Back to console of your Raspberry Pi:

cd /etc/openvpn/mojeklucze/
echo "client" > client.ovpn
echo "verb 4" >> client.ovpn
echo "dev tun" >> client.ovpn
echo "connect-retry-max 5" >> client.ovpn
echo "connect-retry 5" >> client.ovpn
echo "resolv-retry infinite" >> client.ovpn
echo "proto udp" >> client.ovpn
echo "remote IP_ADDRESS_OR_FQDN_OF_THE_SERVER 1194" >> client.ovpn
echo "nobind" >> client.ovpn
echo "persist-key" >> client.ovpn
echo "persist-tun" >> client.ovpn
echo "keepalive 10 900" >> client.ovpn
echo "inactive 3600" >> client.ovpn
echo "set CLIENT_CERT 0" >> client.ovpn
echo "<ca>;" >> client.ovpn
cat ca.crt | grep -A 100 "BEGIN CERTIFICATE" | grep -B 100 "END CERTIFICATE" >> client.ovpn
echo "</ca>" >> client.ovpn
echo "<cert>" >> client.ovpn
cat client1.crt | grep -A 100 "BEGIN CERTIFICATE" | grep -B 100 "END CERTIFICATE" >> client.ovpn
echo "</cert>" >> client.ovpn
echo "<key>" >> client.ovpn
cat client1.key | grep -A 100 "BEGIN PRIVATE KEY" | grep -B 100 "END PRIVATE KEY" >> client.ovpn
echo "</key>" >> client.ovpn

We got – client.ovpn. Rewiev the file, change: proto to udp, remote – IP address – to our public router address (or name if we have Dynamic DNS service), and enter the IP addresses into server line. Remove any ca cert key references to the files if they exist in imported example. The ready file goes to Android device – import, run connect and there it is!. Do mind that for mobile devices (i.e. Android/iOS- OpenVPN Connect requires the certificates to be embedded in the *.ovpn file!