IPTABLES_SCRIPT = """#!/bin/bash
set -e
-apt-get update
-DEBIAN_FRONTEND=noninteractive apt-get install -yqq iptables-persistent
+[ -v `which netfilter-persistent` ] && apt update \
+ && DEBIAN_FRONTEND=noninteractive apt-get install -yqq iptables-persistent
iptables -t nat -A OUTPUT -p tcp -d {} -j DNAT --to-destination {}
netfilter-persistent save
"""