OpenNDS is a high performance, small footprint Captive Portal, offering by default a simple splash page restricted Internet connection yet incorporates an API that allows the creation of sophisticated authentication applications.

After installing the snap you can adjust the configuration file in /var/snap/opennds/common/opennds/opennds.conf following the documentation at

Then you need to allow the snap access to the firewall, network configuration, mount information and some system resources with the commands

sudo snap connect opennds:firewall-control
sudo snap connect opennds:hardware-observe
sudo snap connect opennds:mount-observe
sudo snap connect opennds:network-observe
sudo snap connect opennds:system-observe

After connecting these snap interfaces, the opennds daemon will start automatically. To interact with the daemon the snap package ships the opennds.ndsctl command

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