A sample snippet for editing OpenWrt firewall zone configuration via the UCI command interface. As zone sections are anonymous sections some extra code is needed to discover them. To the extent that the work is copyrightable, it is licensed under the MIT/X11 License.

zz_firewall_add_network.sh

#!/bin/sh
# Copyright (c) 2020 Magnus Kroken
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. /lib/functions.sh

lanzone_cfgid=""
wanzone_cfgid=""

find_firewall_zones () {
        local config="$1"
        local zone_name

        config_get zone_name "$config" name

        if [ "$zone_name" == "lan" ]
        then
                lanzone_cfgid="$config"
        elif [ "$zone_name" == "wan" ]
        then
                wanzone_cfgid="$config"
        fi

        return 0
}

config_load firewall
config_foreach find_firewall_zones zone

uci -q add_list firewall.${wanzone_cfgid}.network='wwan'

uci -q commit firewall
/etc/init.d/firewall reload

exit 0