iiab/roles/2-common/tasks/network.yml

# 2022-03-16: 'apt show <pkg> | grep Size' revealed download sizes, on 64-bit RasPiOS with desktop.

- name: Install package networkd-dispatcher (OS's other than RasPiOS)
  package:
    name: networkd-dispatcher    # 15kB download: Dispatcher service for systemd-networkd connection status changes
    state: present
  when: not is_raspbian

# 2021-07-27 from @jvonau: 3 apt packages BELOW (iw, rfkill, wireless-tools)
# are provided by RasPiOS.  Ubuntu|Debian on the other hand are hit or miss:
# desktops might have some/all 3 preinstalled, while servers tend not to have
# these present at all, but need to be installed if you want to take full
# advantage of WiFi on Ubuntu and friends.
#
# 2022-03-16 update: Let's make these 3 mandatory as they're only 300kB (grand
# total download size) and they can help IIAB field operators with BOTH
# (1) internal WiFi AND (2) USB WiFi devices inserted anytime/later.

- name: 'Install 11 network packages: avahi-daemon, hostapd, iproute2, iptables-persistent, iw, libnss-mdns, netmask, net-tools, rfkill, wpasupplicant, wpasupplicant -- later used by https://github.com/iiab/iiab/tree/master/roles/network'
  package:
    name:
      - avahi-daemon           #   97kB download: RasPiOS (and package libnss-mnds, below) install this regardless -- holdover from the XO days and used to advertise ssh/admin-console being available via avahi-daemon -- used with https://github.com/iiab/iiab/blob/master/roles/network/tasks/avahi.yml
      #- avahi-discover        #   46kB download: 2021-07-27: Commented out long ago
      - hostapd                #  764kB download: IEEE 802.11 AP and IEEE 802.1X/WPA/WPA2/EAP Authenticator -- has its service masked out of the box, and only used when IIAB's network roles detects the presence of WiFi and an AP is desired
      #- inetutils-syslogd     #  240kB download: 2021-07-27: Error logging facility -- holdover from the XO days, journalctl has replaced this in newer distros
      - iproute2               #  902kB download: RasPiOS installs this regardless -- the new networking and traffic control tools, meant to replace net-tools
      - iptables-persistent    #   12kB download: Boot-time loader for netfilter rules, iptables (firewall) plugin -- however Netfilter / nftables is ever moving forward so keep an eye on it!
      - iw                     #   97kB download: RasPiOS installs this regardless -- configure Linux wireless devices -- hard dependence for ap0 creation, SEE https://github.com/iiab/iiab/blob/master/roles/network/templates/hostapd/iiab-clone-wifi.service.j2
      - libnss-mdns            #   27kB download: RasPiOS (and package avahi-daemon, above) install this regardless -- client-side library -- provides name resolution via mDNS (Multicast DNS) using Zeroconf/Bonjour e.g. Avahi
      - netmask                #   25kB download: Handy utility -- helps determine network masks
      - net-tools              #  248kB download: RasPiOS installs this regardless -- @jvonau suggests possibly deleting this...unless oldtimers really want these older commands in iiab-diagnostics output?
      - rfkill                 #   87kB download: RasPiOS installs this regardless -- enable & disable wireless devices
      - wireless-tools         #  112kB download: RasPiOS installs this regardless -- manipulate Linux Wireless Extensions
      - wpasupplicant          # 1188kB download: RasPiOS installs this regardless -- client library for connections to a WiFi AP
    state: present

# 2021-08-17: Debian ignores this, according to 2013 post:
# https://serverfault.com/questions/511099/debian-ignores-etc-network-if-pre-up-d-iptables
# - name: Install /etc/network/if-pre-up.d/iptables from template (0755)
#   template:
#     src: iptables
#     dest: /etc/network/if-pre-up.d/iptables
#     mode: '0755'


# Ongoing rework (e.g. PR #2652) arising from ansible.posix collection changes:
- name: "Use 'sysctl' to set 'kernel.core_uses_pid: 1' + 4 network settings in /etc/sysctl.conf -- e.g. disabling IPv6 (this might be overkill, as IPv6 should really only be disabled on the LAN side, i.e. br0)"
  sysctl:    # Places these settings in /etc/sysctl.conf, to survive reboot
    name: "{{ item.name }}"
    value: "{{ item.value }}"
  with_items:
    - { name: 'net.ipv4.ip_forward', value: '1' }  # Masquerading LAN->Internet
    - { name: 'net.ipv4.conf.default.rp_filter', value: '1' }
    - { name: 'net.ipv4.conf.default.accept_source_route', value: '0' }
    #- { name: 'kernel.sysrq', value: '1' }             # OS values differ, Ok?
    - { name: 'kernel.core_uses_pid', value: '1' }
    #- { name: 'net.ipv4.tcp_syncookies', value: '1' }  # Very standard in 2020
    #- { name: 'kernel.shmmax', value: '268435456' }    # OS values differ, Ok?
    - { name: 'net.ipv6.conf.all.disable_ipv6', value: '1' }    # IPv6 disabled
    #- { name: 'net.ipv6.conf.default.disable_ipv6', value: '1' }    # AUTO-SET
    #- { name: 'net.ipv6.conf.lo.disable_ipv6', value: '1' }         # BY ABOVE