====== Export DHCP Reservations from an NVRAM cfg file into a JSON file for the web interface ======

This Bash script will extract DHCP Reservations from an older backup .cfg file and output them to a JSON file. The JSON file file can then be imported via FreshTomato's web interface. This can be useful when the router.cfg file from which you want to extract DHCP reservations didn't support the reservations backup feature in the web interface.

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The script must be executed from within a router's command-line interface or an SSH session.

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<code bash static2json.sh>
#!/bin/sh

# Convert NVRAM DHCP Reservation to GUI JSON format
# For FreshTomato
# By HommeOursPorc - 2026-04-21

# Usage:
# static2json.sh <infile.cfg> <outfile.json>

# $1 is infile.cfg file
# $2 is outfile.json file

usage() {
    echo "Convert NVRAM DHCP Reservation to GUI JSON format"
    echo "Usage: static2json.sh <infile.cfg> <outfile.json>"
}

NV_CFG="$1"
NV_CONV="/tmp/2json_nv.tmp"
DHCPD_STATIC="/tmp/2json_static.tmp"
CSTATS="/tmp/2json_cstats.tmp"
JSON="$2"

[ $# -ne 2 ] && usage && exit 1
[ ! -s "$NV_CFG" -o ! -d "$(dirname "$JSON")" ] && usage && exit 2

nvram convert "$NV_CFG" "$NV_CONV" &>/dev/null
grep "dhcpd_static" "$NV_CONV" | awk -F'=' '{print $2}' | tr ">" "\n" > "$DHCPD_STATIC"
grep "cstats_include" "$NV_CONV" | awk -F'=' '{print $2}' > "$CSTATS"

exec > "$JSON"

echo '{
  "nextpage": "basic-static.asp",
  "grids": {
    "bs-grid": ['

c=0
for i in $(cat "$DHCPD_STATIC"); do
    MAC="$(echo "$i" | cut -d'<' -f1)"
    IP="$(echo "$i" | cut -d'<' -f2)"
    HOSTNAME="$(echo "$i" | cut -d'<' -f3)"
    ARP="$(echo "$i" | cut -d'<' -f4)"
    if [ $(grep -cw "$IP" "$CSTATS") -gt 0 ]; then
        IPTRAFFIC=1
    else
        IPTRAFFIC=0
    fi

    if [ $(echo "$MAC" | grep -c ',') -eq 1 ]; then
        MAC1="$(echo "$MAC" | cut -d',' -f1)"
        MAC2="$(echo "$MAC" | cut -d',' -f2)"
    else
        MAC1="$MAC"
        MAC2="00:00:00:00:00:00"
    fi
   
    [ $c -gt 0 ] && echo ","
    echo -n "      [
        \"$MAC1\",
        \"$MAC2\",
        \"$ARP\",
        \"$IP\",
        \"$IPTRAFFIC\",
        \"$HOSTNAME\"
      ]"
     
      c=$(($c+1))
done

echo -ne "\n    ]
  }
}"

rm -f "$NV_CONV" "$DHCPD_STATIC" "$CSTATS"

exit 0
</code>

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