by A (very) quick ‘howto’ to make a wireless access point from a Linux machine (should also with with Raspberry Pi with some modifications to the config files)
NOTE: This howto assumes you already have a supported wireless network adaptor – not all adaptors support AP mode.
Requirements: ifupdown / bridge-utils/ crda / wireless-regdb / hostapd / aircrack-ng
Apt commands to remove / install the software as required.
apt purge nplan netplan.io apt install ifupdown apt install bridge-utils apt install wireless-regdb apt install crda apt install hostapd apt install aircrack-ng
My wireless adaptor is wlp2s0 – airmon-ng creates wlp2s0mon (you will need to change wlp2s0 for your adaptor, and airmon-ng will create an adaptor based on that name – you will need to adjust the info below accordingly)
Network configuration: (/etc/network/interfaces) – create the bridge br0 and assign the Ethernet and wireless interfaces to it.
allow-hotplug wlp2s0
auto br0
iface br0 inet static
pre-up { brctl addbr br0 && brctl addif enp3s0 wlp2s0; } || true
bridge_ports enp3s0
address 192.168.1.1
network 192.168.1.0
netmask 255.255.255.0
broadcast 192.168.1.255
gateway 192.168.1.254
Create configs in /etc/default
/etc/default/airmong
# airmon options ARG1='start' ARG2='wlp2s0'
/etc/default/hostapd
ARG1='-i' ARG2='wlp2s0mon' ARG3='/etc/hostapd/hostapd-simple.conf'
hostapd config
/etc/hostapd/hostapd-simple.conf
#### Interface configuration #### interface=wlp2s0mon # interface=wlp2s0 bridge=br0 driver=nl80211 ##### IEEE 802.11 related configuration ##### ssid=linux-ap hw_mode=g # hw_mode=n # unsupported (for me) channel=4 wmm_enabled=1 country_code=GB ieee80211d=1 ieee80211h=0 ##### IEEE 802.11n related configuration ##### ieee80211n=1 ##### WPA/IEEE 802.11i configuration ##### auth_algs=1 # wpa only # wpa2 only wpa=2 wpa_key_mgmt=WPA-PSK wpa_pairwise=CCMP wpa_passphrase=[your passphrase] macaddr_acl=0
Create systemd unit files in /etc/systemd/system
airmon.service
[Unit] Description=Airmon service After=network.target StartLimitIntervalSec=0 [Service] Type=simple # Restart= # RestartSec=1 EnvironmentFile=/etc/default/airmong User=root ExecStart=/usr/sbin/airmon-ng $ARG1 $ARG2 [Install] WantedBy=multi-user.target
hostapd.service
[Unit] Description=Hostapd service After=sys-class-net-wlp2s0mon.device airmon.service StartLimitIntervalSec=0 [Service] Type=simple EnvironmentFile=/etc/default/hostapd User=root ExecStartPre=/usr/bin/sleep 3 ExecStart=/usr/sbin/hostapd $ARG1 $ARG2 $ARG3 [Install] WantedBy=multi-user.target
NOTE: Some of the sites below recommend installing dnsmasq – but I already have DHCP and DNS servers on my network so dnsmasq was not required in my case. As always, your use case might differ.
Sources:
https://stackoverflow.com/questions/70944393/hostapd-free-hapd-data-interface-wlan0-wasnt-started
https://forum.doozan.com/read.php?2,6300
https://www.shubhamdipt.com/blog/how-to-create-a-systemd-service-in-linux/
https://unix.stackexchange.com/questions/257888/systemd-wait-for-network-interface-to-be-up-before-running-service
https://pychao.com/2021/02/24/difference-between-partof-and-bindsto-in-a-systemd-unit/
https://stackoverflow.com/questions/43001223/how-to-ensure-that-there-is-a-delay-before-a-service-is-started-in-systemd
https://wiki.gentoo.org/wiki/Hostapd#802.11b.2Fg.2Fn_with_WPA2-PSK_and_CCMP
https://superuser.com/questions/728951/systemd-giving-my-service-multiple-arguments
https://askubuntu.com/questions/472794/hostapd-error-nl80211-could-not-configure-driver-mode
https://medium.com/@renaudcerrato/how-to-build-your-own-wireless-router-from-scratch-part-3-d54eecce157f