ctables

#!/bin/bash
#
# https://github.com/deitch/ctables
#
NSPID=${1}
LINKFILE="/var/run/netns/${NSPID}"
mkdir -p /var/run/netns
/bin/rm -f "$LINKFILE"
ln -s "/proc/$NSPID/ns/net" "$LINKFILE"
ip netns exec ${NSPID} iptables -I INPUT -j REJECT
ip netns exec ${NSPID} iptables -I INPUT -i lo -j ACCEPT
ip netns exec ${NSPID} iptables -I INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
# Replace 10.0.0.0/24 with your servers IP's or ranges
ip netns exec ${NSPID} iptables -I INPUT -s 10.0.0.0/24 -j ACCEPT
# Replace 10.10.0.0/16 with your OpenVPN IP Range
ip netns exec ${NSPID} iptables -I INPUT -s 10.10.0.0/16 -j ACCEPT
ip netns exec ${NSPID} iptables -I OUTPUT -o lo -j ACCEPT
ip netns exec ${NSPID} iptables -A OUTPUT -m conntrack --ctstate ESTABLISHED -j ACCEPT
# Add any custom routes you may need.
# ip netns exec ${NSPID} ip route add 10.194.0.0/16 via 10.0.0.243
/bin/rm -f "$LINKFILE"
# Modify file permissions inside the container
if [ -f /proc/$NSPID/root/usr/bin/pkexec ]; then
        chmod -s /proc/$NSPID/root/usr/bin/pkexec
fi