Configuring Wi-Fi
The Raspberry Pi Wi-Fi adapter has two main operating modes:
- Client mode – RPi connects to an existing Wi-Fi network.
- Access point mode – RPi creates a Wi-Fi network that you can connect to.
On our RPi image the Wi-Fi adapter is configured to use the access point mode by default.
Changing the password or SSID (of the network name)
Edit the
/etc/wpa_supplicant/wpa_supplicant.conf
file (using SSH connection):sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
In order to change the name of the Wi-Fi network, change the value of the
ssid
parameter; to change the password, change thepsk
parameter. For example:network={ ssid="my-super-ssid" psk="cloverwifi123" mode=2 proto=RSN key_mgmt=WPA-PSK pairwise=CCMP group=CCMP auth_alg=OPEN }
Restart Raspberry Pi.
WARNING
The Wi-Fi network password should be at least 8 characters.
If your wpa_supplicant.conf
is not valid, Raspberry Pi will not allow Wi-Fi connections!
Switching adapter to the client mode
Disable the
dnsmasq
service.sudo systemctl stop dnsmasq sudo systemctl disable dnsmasq
Enable DHCP client on the wireless interface to obtain IP address. In order to do this, remove the following lines from the
etc/dhcpcd.conf
file:interface wlan0 static ip_address=192.168.11.1/24
Configure
wpa_supplicant
to connect to an existing access point. Change your/etc/wpa_supplicant/wpa_supplicant.conf
to contain the following:ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev update_config=1 country=GB network={ ssid="SSID" psk="password" }
where
SSID
is the name of the network, andpassword
is its password.Restart the
dhcpcd
service.sudo systemctl restart dhcpcd
Switching the adapter to the access point mode
Enable the static IP address in the wireless interface. Add the following lines to your
/etc/dhcpcd.conf
file:interface wlan0 static ip_address=192.168.11.1/24
Configure wpa_supplicant to work in the access point mode. Change your
/etc/wpa_supplicant/wpa_supplicant.conf
file to contain the following:ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev update_config=1 country=GB network={ ssid="clover-1234" psk="cloverwifi" mode=2 proto=RSN key_mgmt=WPA-PSK pairwise=CCMP group=CCMP auth_alg=OPEN }
where
clover-1234
is the network name andcloverwifi
is the password.Enable the
dnsmasq
service.sudo systemctl enable dnsmasq sudo systemctl start dnsmasq
Restart the
dhcpcd
service.sudo systemctl restart dhcpcd
Below you can read more about how RPi networking is organized.
RPi network organization
Network operation in the image is supported by two pre-installed services:
- networking — the service enables all network interfaces at startup [5].
- dhcpcd — the service ensures that configuration of addressing and routing on the interfaces is obtained dynamically or specified statically in the config file.
To work in the router (access point) mode, RPi requires a DHCP server. It is used to automatically send the settings of the current network to connected clients. isc-dhcp-server
or dnsmasq
may be used for this.
dhcpcd
Starting with Raspbian Jessie, network settings are no longer defined in the /etc/network/interfaces
file. Now dhcpcd
is used for sending addressing and routing settings[4].
By default, a dhcp client is enabled in all interfaces. Settings for network interfaces are changed in the /etc/dhcpcd.conf
file. An access point should have a static IP address. To specify one, add the following lines to the end of the file:
interface wlan0
static ip_address=192.168.11.1/24
TIP
If the interface is wireless (wlan), the dhcpcd
service triggers wpa_supplicant
[13], which in turn works directly with the Wi-Fi adapter, and sets it to the specified state.
wpa_supplicant
wpa_supplicant — the service configures the Wi-Fi adapter. The wpa_supplicant
service does not run as a standalone service (although it exists as such), but is instead launched as a dhcpcd
child process.
By default the config file is /etc/wpa_supplicant/wpa_supplicant.conf
. An example of the configuration file:
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=GB
network={
ssid=\"my-clover\"
psk=\"cloverwifi\"
mode=2
proto=RSN
key_mgmt=WPA-PSK
pairwise=CCMP
group=CCMP
auth_alg=OPEN
}
Inside the config file, general wpa_supplicant
settings, and the settings for the adapter configuration are specified. The configuration file also contains network
section with the basic settings of the Wi-Fi network, such as network SSID, password, adapter operating mode. There may be several network
sections, but only the first valid one is used. For example, if the first section contains a connection to an unavailable network, the adapter will be configured according to a next valid section, if there is one. Read more about the syntax of wpa_supplicant.conf
[TODO WIKI].
wpa_passphrase
wpa_passphrase
— a utility for creating the network
section.
wpa_passphrase SSID PASSWORD
After running the command, copy the resulting section to your config file. You may remove the commented field psk
, and leave only the field with the password hash, or vice versa.
network={
ssid="SSID"
#psk="PASSWORD"
psk=c2161655c6ba444d8df94cbbf4e9c5c4c61fc37702b9c66ed37aee1545a5a333
}
Multiple Wi-Fi adapters
The system may use multiple Wi-Fi adapters. If drivers are properly connected to them, they may be viewed by calling ifconfig
(e.g. wlan0
and wlan1
).
If you have multiple adapters, the same working network
section will be used for all of them. This is due to the fact that for each interface, dhcpcd
separately creates a child wpa_supplicant
process, which runs the same code ( since the config is the same).
To make multiple adapters work with individual settings, the mechanism for running different configuration scripts is implemented in the called standard dhcpcd
script. To use it, rename the standard config file as follows: wpa_supplicant-<interface name>.conf
, for example wpa_supplicant-wlan0.conf
.
To apply the settings, restart the parent process — the dhcpcd
service. This can be done by running the following command:
sudo systemctl restart dhcpcd
DHCP server
dnsmasq-base
dnsmasq-base
— a command-line utility, which is not a service. To use dnsmasq as a service, install the dnsmasq
package.
sudo apt install dnsmasq-base
# Calling dnsmasq-base
sudo dnsmasq --interface=wlan0 --address=/clover/coex/192.168.11.1 --no-daemon --dhcp-range=192.168.11.100,192.168.11.200,12h --no-hosts --filterwin2k --bogus-priv --domain-needed --quiet-dhcp6 --log-queries
# More about dnsmasq-base
dnsmasq --help
# or
man dnsmasq
dnsmasq
sudo apt install dnsmasq
cat << EOF | sudo tee -a /etc/dnsmasq.conf
interface=wlan0
address=/clover/coex/192.168.11.1
dhcp-range=192.168.11.100,192.168.11.200,12h
no-hosts
filterwin2k
bogus-priv
domain-needed
quiet-dhcp6
EOF
isc-dhcp-server
sudo apt install isc-dhcp-server
# https://www.shellhacks.com/ru/sed-find-replace-string-in-file/
sed -i 's/INTERFACESv4=\"\"/INTERFACESv4=\"wlan0\"/' /etc/default/isc-dhcp-server
cat << EOF | sudo tee /etc/dhcp/dhcpd.conf
subnet 192.168.11.0 netmask 255.255.255.0 {
range 192.168.11.11 192.168.11.254;
#option domain-name-servers 8.8.8.8;
#option domain-name "rpi.local";
option routers 192.168.11.1;
option broadcast-address 192.168.11.255;
default-lease-time 600;
max-lease-time 7200;
}
EOF
cat << EOF | sudo tee /etc/network/if-up.d/isc-dhcp-server && sudo chmod +x /etc/network/if-up.d/isc-dhcp-server
#!/bin/sh
if [ "\$IFACE" = "--all" ];
then sleep 10 && systemctl start isc-dhcp-server.service &
fi
EOF
Links
- habr.com Linux WiFi from the command line with wpa_supplicant
- wiki.archlinux.org WPA supplicant (Russian)
- blog.hoxnox.com: WiFi access point with wpa_supplicant
- dmitrysnotes.ru: Raspberry Pi 3. Assigning a static IP addresses
- thegeekdiary.com: Linux OS Service ‘network’
- frillip.com: Using your new Raspberry Pi 3 as a Wi-Fi access point with hostapt (it also contains instructions for setting up forwarding for using RPi as an Internet gateway)
- habr.com: Configuring a ddns server on a GNU/Linux Debian 6 (Good article on configuring a ddns server based on
bind
andisc-dhcp-server
) - pro-gram.ru to: Setting up and configuring a DHCP server in Ubuntu 16.04. (setup isc-dhcp-server)
- expert-orda.ru: Configuring a DHCP server in Ubuntu (setup isc-dhcp-server)
- academicfox.com: A Raspberry Pi wireless access point (WiFi access point) (setting the routes, hostapd, isc-dhcp-server)
- weworkweplay.com: Automatically connect a Raspberry Pi to a Wifi network (Contains settings for creating an open access point)
- wiki.archlinux.org: WPA supplicant
- wiki.archlinux.org: dhcpcd (dhcpcd hook wpa_supplicant)