Two uses for Single Board Computers

Abdun Nihaal
https://nihaal.me
11 September 2021 at ILUGC
Creative Commons License

Single Board Computers

  • Low power computers
  • Can run Linux
  • Eg: Raspberry Pi, Beagle Bone, etc
  • IoT applications, Home servers

Image by Kevin Partner from Pixabay

Setup Static IP

  • Need Static IP to connect

  • Add to /etc/dhcpcd.conf 

    interface wlan0
static ip_address=192.168.0.200/24
static routers=192.168.0.1
static domain_name_servers=192.168.0.1

Reducing power consumption

  • Setup SSH and run headless (without monitor)

  • Power off HDMI ports 

    /bin/tvservice -o
  • Unplug peripherals
  • Turn off LEDs

Extending SD card life

  • Disable Swap (try zram instead)
  • Disable Journalling in Ext4 filesystems
  • Frequently written to directories
    1. Mount them from USB drive (/home)
    2. Use tmpfs (/var/log, /tmp)

1. IRC Bounce server with ZNC

znc.png

What is IRC Bounce server?

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ZNC Installation

  • Installing and configuring ZNC 

    sudo apt-get install znc
znc --makeconf

  • Making it start at boot 

    crontab -e
# Add "@reboot znc" to the end

  • Has a Web interface for configuration 

    https://<sbc_ip_address>:<znc_port>

Connecting from an IRC client (Weechat)

  • Add and connect to ZNC server 

    /server add rpi <sbc_ip_address>/<znc_port>
    -username=user -password=pass
    -ssl -autoconnect
/save
/connect rpi

  • Set up SSL fingerprint 

    cat ~/.znc/znc.pem |\
    openssl x509 -sha512 -fingerprint -noout |\
    tr -d ':' | tr 'A-Z' 'a-z' | cut -d = -f 2

2. Pi Hole

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What is Pi Hole?

  • Blocks ads and trackers
  • DNS sinkhole
  • Network wide blocking
  • Blocks in-app ads
  • Uses a list of common tracker URLs

How it works? For normal requests

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How it works? For Ad requests

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Pi hole Installation

  • Installation script 

    curl -sSL https://install.pi-hole.net | bash

  • Change admin password 

    pihole -a -p

  • Has a easy to use web interface 

    https://<ip_address>/admin

Changing DNS to point to Pi Hole (2 ways)

  1. Change DNS on specific devices
    • On Linux
      • /etc/resolv.conf
      • /etc/systemd/resolved.conf
    • On Android
      • Under Advanced WiFi settings
  2. Change DNS on the WiFi router
    • Through your router interface

Thanks

Links