getmac.sh

#!/bin/sh

# Check if hostname is provided
if [ -z "$1" ]; then
    echo "Usage: $0 <hostname>"
    exit 1
fi

# Extract the hostname to look for
hostname=$1

awk -v hostname="$hostname" '
BEGIN {
    FS="option"
    name = ""
    mac = ""
}

/^config host/ {
    name = ""
    mac = ""
}

/name/ {
    split($2, a, " ")
    name = a[2]
    gsub("\047", "", name)
    if (name == hostname && mac != "") {
        print mac
        exit
    }
}

/mac/ {
    split($2, a, " ")
    mac = a[2]
    gsub("\047", "", mac)
    if (name == hostname && mac != "") {
        print mac
        exit
    }
}' /etc/config/dhcp

manage.sh

#!/bin/sh

if [ $# -ne 2 ]
  then
    echo "Usage: manage.sh <block|unblock> <hostname>"
    exit 1
fi

ACTION=$1
HOSTNAME=$2

MAC_ADDRESS=$(getmac.sh ${HOSTNAME})

if [ -z "$MAC_ADDRESS" ]
  then
    echo "Unable to find MAC address for $HOSTNAME."
    exit 1
fi

RULE_NAME="Block-${HOSTNAME}-${MAC_ADDRESS//:/_}"

case "$ACTION" in
    block)
        uci add firewall rule
        uci set firewall.@rule[-1].name="$RULE_NAME"
        uci set firewall.@rule[-1].src='lan'
        uci set firewall.@rule[-1].dest='wan'
        uci set firewall.@rule[-1].proto='all'
        uci set firewall.@rule[-1].src_mac="$MAC_ADDRESS"
        uci set firewall.@rule[-1].target='REJECT'
        uci commit firewall
        /etc/init.d/firewall restart
        echo "Device with hostname $HOSTNAME and MAC address $MAC_ADDRESS has been blocked from accessing the WAN."
        ;;
    unblock)
        RULE_ID=$(uci show firewall | grep -w "firewall.@rule" | grep -w "name='$RULE_NAME'" | cut -d'[' -f2 | cut -d']' -f1)

        if [ -z "$RULE_ID" ]
          then
            echo "No rule found for hostname $HOSTNAME and MAC address $MAC_ADDRESS."
            exit 1
        fi

        uci delete firewall.@rule[$RULE_ID]
        uci commit firewall
        /etc/init.d/firewall restart
        echo "Device with hostname $HOSTNAME and MAC address $MAC_ADDRESS has been unblocked from accessing the WAN."
        ;;
    *)
        echo "Invalid action. Usage: manage.sh <block|unblock> <hostname>"
        exit 1
        ;;
esac