Brainstorm's snippets (1/239)

  Raspberry PI setup guide

1   Initial setup

Eventually expand file system if part of the SD is unused:

raspi-config --expand-rootfs

2   Enable SSH connections

Connect with a keyboard, then issue these commands from terminal:

systemctl enable ssh.service
systemctl start ssh.service

3   Set locale

sudo -s
export LANGUAGE=en_US.UTF-8
export LANG=en_US.UTF-8
export LC_ALL=en_US.UTF-8
locale-gen en_US.UTF-8
dpkg-reconfigure locales

5   Expand swap partition ...

100 Mb (the default) is too small, and if you are doing memory intensive stuff (e.g., web surfing), you can easily max it out.

The recommended swap size is 2*physical RAM - in the case of the Pi (modern/current versions of), this is 2G.

You can increase the swap size by changing the CONF_SWAPSIZE or the CONF_SWAPFACTOR parameter in /etc/dphys-swapfile followed by a reboot:

cat /etc/dphys-swapfile

[...]
CONF_SWAPFACTOR=2
[...]

Test after reboot:

# free -h
              total        used        free      shared  buff/cache   available
Mem:           927M        259M        425M         30M        242M        585M
Swap:          1.8G          0B        1.8G

6   ... or remove it !

On the other hand, you might want to turn off swap entirely in order to reduce the amount of write operations on the SD card – because SD cards have their life limited to the amount of write operations:

sudo systemctl disable dphys-swapfile

Test after reboot:

# free -h
              total        used        free      shared  buff/cache   available
Mem:           927M        257M        437M         24M        232M        593M
Swap:            0B          0B          0B

Another option is to move swap to an external device (for example a USB key).

References:

7   Setup SMTP

TODO; vedere:

Installazione e Configurazione di Postfix su Raspberry usando come Smarthost GMAIL:

https://www.raffaelechiatto.com/installazione-configurazione-postfix-raspberry-usando-smarthost-gmail/

NULLMAILER – IL POSTINO MINIMALISTA:

https://hamradio.fe.linux.it/nullmailer-il-postino-minimalista/

8   Start chromium in Kiosk mode on raspbian jessie

file ~/Desktop/runChromium.desktop:

[Desktop Entry]
Type=Application
Exec=/usr/bin/chromium-browser --noerrdialogs --disable-session-crashed-bubble --disable-infobars --kiosk http://127.0.0.1
Hidden=false
X-GNOME-Autostart-enabled=true
Name[en_US]=RunChromium
Name=RunChromium
Comment=Start Chromium in kiosk mode; copy int ~/.config/autostart to have it run automatically

References:

9   Pi display

How to hide the cursor in the kiosk mode automatically:

sudo apt-get install unclutter

then add this to file /etc/xdg/lxsession/LXDE/autostart:

@unclutter -idle 0.1 -root

10   Display rotation

file "/boot/config.txt":

# LCD Rotation
lcd_rotate=2

# Display Rotate (HDMI)
#display_rotate=2

11   Disable screen sleep

file "/etc/lightdm/lightdm.conf":

[Seat:*]
...
# don't sleep the screen
xserver-command=X -s 0 dpms

or:

sudo apt-get install xscreensaver

then configure the screensaver application under the Preferences option on the main desktop menu.

12   How to up a Static IP on Your Ethernet or Wireless Network Connection

file /etc/dhcpcd.conf:

# setup ethernet static ip
interface eth0
inform 192.168.1.18
static routers=255.255.255.0

# setup wireless static ip
interface wlan0
inform 192.168.1.19
static routers=255.255.255.0

or:

# setup ethernet static ip
interface eth0
static ip_address=172.26.11.85/24
static routers=172.26.11.100
static domain_name_servers=8.8.8.8 8.8.4.4

then:

#sudo /etc/init.d/networking restart
sudo reboot

https://projects.raspberrypi.org/en/projects/getting-started-with-picamera

13   Setting up a Raspberry Pi as an access point in a standalone network (NAT)

Brief summary:

Install required software:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install dnsmasq hostapd

then stop the services and reboot:

sudo systemctl stop dnsmasq
sudo systemctl stop hostapd
sudo reboot

Configuring a static IP for wlan0:

add this to /etc/dhcpcd.conf:

interface wlan0
    static ip_address=192.168.4.1/24
    nohook wpa_supplicant

then:

sudo service dhcpcd restart

Configuring the DHCP server (dnsmasq):

sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.orig
sudo vim /etc/dnsmasq.conf

and add:

interface=wlan0      # Use the require wireless interface - usually wlan0
    dhcp-range=192.168.4.2,192.168.4.20,255.255.255.0,24h

Configuring the access point host software (hostapd):

add this to /etc/hostapd/hostapd.conf:

interface=wlan0
driver=nl80211
ssid=NETWORK_NAME
hw_mode=g
channel=7
wmm_enabled=0
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=NETWORK_PASSPHRASE
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

where:

  • NETWORK_PASSPHRASE: between 8 and 64 characters

  • hw_mode:

    • a = IEEE 802.11a (5 GHz)
    • b = IEEE 802.11b (2.4 GHz)
    • g = IEEE 802.11g (2.4 GHz)
    • ad = IEEE 802.11ad (60 GHz)

Add this to /etc/default/hostapd:

DAEMON_CONF="/etc/hostapd/hostapd.conf"

Start the access point host software:

sudo systemctl start hostapd
sudo systemctl start dnsmasq

if necessary:

sudo systemctl unmask hostapd
sudo systemctl enable hostapd
sudo systemctl start hostapd

Add routing and masquerade:

Uncomment this line in /etc/sysctl.conf:

net.ipv4.ip_forward=1

Add a masquerade for outbound traffic on eth0:

sudo iptables -t nat -A  POSTROUTING -o eth0 -j MASQUERADE

Save the iptables rule:

sudo sh -c "iptables-save > /etc/iptables.ipv4.nat"

Edit /etc/rc.local and add this just above "exit 0" to install these rules on boot:

iptables-restore < /etc/iptables.ipv4.nat

Reboot and done !

References:

Setting up a Raspberry Pi as an access point in a standalone network (NAT)

15   Installing Python 3.7.x on Raspbian

sudo su
cd
mkdir downloads
cd downloads

apt-get update -y
apt-get install build-essential tk-dev libncurses5-dev libncursesw5-dev libreadline6-dev libdb5.3-dev libgdbm-dev libsqlite3-dev libssl-dev libbz2-dev libexpat1-dev liblzma-dev zlib1g-dev libffi-dev -y
wget https://www.python.org/ftp/python/3.7.2/Python-3.7.2.tar.xz
tar xf Python-3.7.2.tar.xz
cd Python-3.7.2
./configure
make -j 4
make altinstall
cd ..
rm -r Python-3.7.2
rm Python-3.7.2.tar.xz
apt-get --purge remove build-essential tk-dev libncurses5-dev libncursesw5-dev libreadline6-dev libdb5.3-dev libgdbm-dev libsqlite3-dev libssl-dev libbz2-dev libexpat1-dev liblzma-dev zlib1g-dev libffi-dev -y
apt-get autoremove -y
apt-get clean

References:

16   todo

All my Pi's (including Pi Zero's) have these two lines added to /etc/fstab:

tmpfs /tmp tmpfs defaults,noatime,nosuid 0 0
tmpfs /var/log tmpfs defaults,noatime,nosuid,size=16m 0 0

The default maximum size is half the memory, but of course tmpfs only takes as much memory as the files need.

While you are in /etc/fstab, if you want to reduce writes to the SD then the other simple change is the flush rate.

For the ext4 / mount make sure the options include "commit=600" That is, for example:

PARTUUID=e96d960e-02 / ext4 defaults,noatime,commit=600,errors=remount-ro 0 1

Obviously do not do this if your site is prone to power cuts or other unexpected outages. (dirty pages in the disk cache are written out every ten minutes instead of every five seconds which is the default). This improves performance as well.