36. Networking¶

SolarNodeOS uses the systemd-networkd service to manage network devices and their settings. A network device relates to a physical network hardware device or a software networking component, as recognized and named by the operating system. For example, the first available ethernet device is typically named eth0 and the first available WiFi device wlan0.

36.1 Network configuration¶

Network configuration is stored in .network files in the /etc/systemd/network directory. SolarNodeOS comes with default support for ethernet and WiFi network devices.

The default 10-eth.network file configures the default ethernet network eth0 to use DHCP to automatically obtain a network address, routing information, and DNS servers to use.

36.2 DHCP configuration¶

SolarNodeOS networks are configured to use DHCP by default. If you need to re-configure a network to use DHCP, change the configuration to look like this:

[Match]
Name=eth0

[Network]
DHCP=yes

Use a Name value specific to your network.

36.3 Static network configuration¶

If you need to use a static network address, instead of DHCP, edit the network configuration file (for example, the 10-eth.network file for the ethernet network), and change it to look like this:

[Match]
Name=eth0

[Network]
DNS=1.1.1.1

[Address]
Address=192.168.3.10/24

[Route]
Gateway=192.168.3.1

Use Name, DNS, Address, and Gateway values specific to your network. The same static configuration for a single address can also be specified in a slightly more condensed form, moving everything into the [Network] section:

[Match]
Name=eth0

[Network]
Address=192.168.3.10/24
Gateway=192.168.3.1
DNS=1.1.1.1

36.4 WiFi network configuration¶

The default 20-wlan.network file configures the default WiFi network wlan0 to use DHCP to automatically obtain a network address, routing information, and DNS servers to use. To configure the WiFi network SolarNode should connect to, run this command:

sudo dpkg-reconfigure sn-wifi

You will then be prompted to supply the following WiFi settings:

1. Country code, e.g. NZ
2. WiFi network name (SSID)
3. WiFi network password

36.5 WiFi Auto Access Point mode¶

For initial setup of a the WiFi settings on a SolarNode it can be helpful for SolarNode to create its own WiFi network, as an access point. The sn-wifi-autoap@wlan0 service can be used for this. When enabled, it will monitor the WiFi network status, and when the WiFi connection fails for any reason it will enable a SolarNode WiFi network using a gateway IP address of 192.168.16.1. Thus when the SolarNode access point is enabled, you can connect to that network from your own device and reach the Setup App at http://192.168.16.1/ or the command line via ssh solar@192.168.16.1.

The default 21-wlan-ap.network file configures the default WiFi network wlan0 to act as an Access Point

This service is not enabled by default. To enable it, run the following:

sudo systemctl enable --now sn-wifi-autoap@wlan0

Once enabled, if SolarNode cannot connect to the configured WiFi network, it will create its own SolarNode network. By default the password for this network is solarnode. The Access Point network configuration is defined in the /etc/network/wpa_supplicant-wlan0.conf file, in a section like this:

### access-point mode
network={
    ssid="SolarNode"
    mode=2
    key_mgmt=WPA-PSK
    psk="solarnode"
    frequency=2462
}

36.6 Firewall¶

SolarNodeOS uses the nftables system to provide an IP firewall to SolarNode. By default only the following incoming TCP ports are allowed:

36.6.1 Open additional IP ports¶

You can edit the /etc/nftables.conf file to add additional open IP ports as needed. A good place to insert new rules is after the lines that open ports 80 and 8080:

# Allows HTTP
add rule ip filter INPUT tcp dport 80 counter accept
add rule ip filter INPUT tcp dport 8080 counter accept

For example, if you would like to open UDP port 50222 to support the Weatherflow Tempest weather station, add the following after the above lines:

# Allow WeatherFlow Tempest messages
add rule ip filter INPUT udp dport 50222 counter accept

36.6.2 Reload firewall rules¶

If you make changes to the firewall rules in /etc/nftables.conf, run the following command to reload the firewall configuration:

sudo systemctl reload nftables