From the project home page: "Tox is a distributed, secure messenger with audio and video chat capabilities."
Run a node
To be able to connect to others, Tox needs to connect to a DHT node first. All DHT nodes are connected to each other, and since everyone is connected to at least one DHT node, you can connect to others one way or the other.
Install. The package creates user 'tox-bootstrapd' and includes a systemd unit file in /usr/lib/systemd/system/tox-bootstrapd.service and a configuration file in /etc/tox-bootstrapd.conf.
Enable and start tox-bootstrapd.service, and check if it is running fine and port has been bound:
# ss --listening --numeric --processes | grep node_port
udp 0 0 *:node_port *:* 576/DHT_bootstrap