Static IP Address
It is sometimes desirable to provide static IP configuration for network interface instead of relying on DHCP. Below we describe several methods of doing that.
Using ConnMann
ConnMan is the default Yocto network manager. Network manager is a program for providing detection and configuration for systems to automatically connect to network. In the examples below we demonstrate how ConnMan command line tool, connmanctl, can be used create static IP configuration.
Configuring wired interfaces
To get the list of wired interfaces run
# connmanctl services
For example:
root@imx7-var-som:~# connmanctl services *AO Wired ethernet_0eb31468dcc9_cable
Wired interfaces will be shown as ethernet_<mac_address>_cable. Only interfaces physically connected to the network are displayed.
To create static IP configuration run
# connmanctl <service> --ipv4 manual <ip address> <netmask> <gateway> # connmanctl config <service> --nameservers <dns-addr>
For example:
# connmanctl ethernet_0eb31468dcc9_cable --ipv4 manual 192.168.1.100 255.255.255.0 192.168.1.254 # connmanctl config ethernet_0eb31468dcc9_cable --nameservers 8.8.8.8 4.4.4.4
The configuration will be saved in /var/lib/connman/ethernet_0eb31468dcc9_cable/settings.
Configuring wireless interfaces
To check if wifi is enabled run
# connmanctl technologies
and check for the line that says Powered: True/False.
To power the wifi on run
# connmanctl enable wifi
To scan the network connmanctl accepts simple names called technologies. To scan for nearby wifi networks:
# connmanctl scan wifi
To list the available networks found after a scan run (example output):
# connmanctl services
MyNetwork wifi_dc85de828967_68756773616d_managed_psk OtherNET wifi_dc85de828967_38303944616e69656c73_managed_psk AnotherOne wifi_dc85de828967_3257495245363836_managed_wep FourthNetwork wifi_dc85de828967_4d7572706879_managed_wep AnOpenNetwork wifi_dc85de828967_4d6568657272696e_managed_none
Every wifi network is identified by a name composed as
wifi_<hashlocal>_<hashremote>_managed_<encrption>
Connecting to an open network
To connect to an open network, look for wifi networks ending with _managed_none:
# connmanctl connect wifi_dc85de828967_4d6568657272696e_managed_none
You should now be connected to the network. Check using ip addr or run
# connmanctl state.
Connecting to a protected network
Start connmanctl in interactive mode by running
# connmanctl
Now you need to register the agent to handle user requests. The command is:
connmanctl> agent on
You now need to connect to one of the protected services.
To do this easily, just use tab completion for the wifi_ service.
If you were connecting to OtherNET in the example above you would type:
connmanctl> connect wifi_dc85de828967_38303944616e69656c73_managed_psk
The agent will then ask you to provide any information the daemon needs to complete the connection.
The information requested will vary depending on the type of network you are connecting to.
The agent will also print additional data about the information it needs as shown in the example below.
Agent RequestInput wifi_dc85de828967_38303944616e69656c73_managed_psk Passphrase = [ Type=psk, Requirement=mandatory ] Passphrase?
Provide the information requested, in this example the passphrase, and then type:
connmanctl> quit
If the information you provided is correct you should now be connected to the protected access point.
Configuring Static IP
To create static IP configuration run
# connmanctl <service> --ipv4 manual <ip address> <netmask> <gateway> # connmanctl config <service> --nameservers <dns-addr>
For example:
# connmanctl wifi_dc85de828967_38303944616e69656c73_managed_psk --ipv4 manual 192.168.1.100 255.255.255.0 192.168.1.254 # connmanctl config wifi_dc85de828967_38303944616e69656c73_managed_psk --nameservers 8.8.8.8 4.4.4.4
The configuration will be saved in /var/lib/connman/wifi_dc85de828967_38303944616e69656c73_managed_psk/settings.
Using NetworkManager
NetworkManager is an alternative network manager that can be used instead of ConnMann. Both network managers cannot coexist in the same Yocto image, so enabling NetworkManager requires disabling ConnMan and rebuilding the image.
In the examples below we use NetworkManager command line tool, nmcli, to create static configurations.
Configuring wired interfaces
To create static IP configuration run
# nmcli con add type ethernet ifname <ethX> name <name> ip4 <ipaddr> gw4 <gwaddr> # nmcli con mod static-eth0 ipv4.dns "<dns1>,<dns2>"
For example, to create configuration for eth0 run
# nmcli con add type ethernet ifname eth0 name static-eth0 ip4 192.168.1.100/24 gw4 192.168.1.254 # nmcli con mod static-eth0 ipv4.dns "8.8.8.8,4.4.4.4"
The configuration will be saved in /etc/NetworkManager/system-connections/static-eth0.
Configuring wireless interfaces
To check if WIFI is enabled by NetworkManager run
# nmcli dev show wlan0
and check the GENERAL.STATE line. If WIFI is enabled, the state is either connected or disconnected. If WIFI is disabled the state is unavailable.
To enable WIFI run
# nmcli radio wifi on
or if you need to disable it you can run
# nmcli radio wifi off
If WIFI is enabled you can get the list of available APs by running
# nmcli dev wifi list
SSID MODE CHAN RATE SIGNAL BARS SECURITY MyNetwork Infra 149 54 Mbit/s 100 **** WPA1 WPA2 OtherNetwork Infra 11 54 Mbit/s 75 *** WPA2 AnotherNetwork Infra 6 54 Mbit/s 75 *** WPA2 FourthNetwork Infra 64 54 Mbit/s 60 *** WPA2 OpenNetwork Infra 3 54 Mbit/s 37 ** --
To connect to an open WIFI network run
# nmcli dev wifi connect <SSID>
To connect to a protected WIFI network run
# nmcli dev wifi connect <SSID> password <password>
To check connection status run
# nmcli dev show wlan0
Configuring static IP
By default WIFI connection will use DHCP. To switch to static IP configuration run the following commands:
# nmcli con mod <SSID> ipv4.method manual ipv4.addr <ipaddr>/<netmask> ipv4.gateway <gwaddr> ipv4.dns "<dns1>,<dns2>" # nmcli con down <SSID> # nmcli con up <SSID>
For example
# nmcli con mod MyNetwork ipv4.method manual ipv4.addr "192.168.1.100/24" ipv4.gateway 192.168.1.254 ipv4.dns "8.8.8.8,4.4.4.4" # nmcli con down MyNetwork # nmcli con up MyNetwork
The configuration will be saved in /etc/NetworkManager/system-connections/<SSID>.
Using /etc/network/interfaces
This is a legacy method with various limitations and we do not recommend using it, especially in combination with network managers. The configuration file /etc/network/interfaces is used by ifup and ifdown tools to perform network interface configuration. In the SystemV init setup ifup and ifdown are invoked by /etc/init.d/networking boot script. In systemd setup /etc/init.d/networking is not available and you should create your own systemd service file that invokes "ifup -a" on startup and "ifdown -a" at shutdown.
If you configure all network interfaces via /etc/network/interfaces, it is better to completely disable the network manager service.
The example below configures eth0
auto eth0
iface eth0 inet static
address 192.168.1.100
netmask 255.255.255.0
gateway 192.168.1.254
dns-nameservers 8.8.8.8 4.4.4.4
dns-search foo.org bar.com
The DNS settings in /etc/network/interfaces rely on the availability of /sbin/resolvconf tool to update /etc/resolv.conf configuration file. If /sbin/resolvconf is not present, rebuild Yocto image after adding the following line to conf/local.conf
IMAGE_INSTALL_append = " resolvconf"
Configuring WIFI via /etc/network/interfaces is not recommended.
Interaction with ConnMan
ConnMan will override the settings in /etc/network/interfaces unless configured to ignore relevant interfaces. For example, after configuring eth0 and eth1 in /etc/network/interfaces, you should create /etc/connman/main.conf and add the following:
[General] NetworkInterfaceBlacklist=eth0,eth1
ConnMan will also override the contents of /etc/resolv.conf as it includes its own DNS proxy. To prevent that, start ConnMan with the options "-r" or "--nodnsproxy"
Interaction with NetworkManager
NetworkManager may override the contents of /etc/resolv.conf. To prevent that, create /etc/NetworkManager/NetworkManager.conf and add the following:
[main] dns=none