proxmox-utils/wireguard/templates/root/getFreeClientIP

#!/usr/bin/env bash

CLIENT_IPS=${CLIENT_IPS}

BASE_IP=${CLIENT_IPS/.0\/*}
IPs=($(cat /etc/wireguard/clients/* 2> /dev/null \
	| grep Address \
	| cut -d'.' -f 4 \
	| cut -d '/' -f 1 \
	| sort))
IPs=${IPs[@]}

i=1
while [ "$( echo $IPs | fgrep -w $i )" ] ; do
	i=$(( i + 1 ))
done

echo $BASE_IP.$i