OpenVPN: IPv6 routed 2 LAN

Topology

LAN 1 ---------- HOST A ---------------- HOST B -------------- LAN 2
                 ovpn server             ovpn client

2002::/64        2345::1/64              2345::2/64            2003::/64

HOST A OpenVPN Server

OS   : Ubuntu 18.04
IP   : 192.168.0.239/24
IP   : 2345::1/64
LAN1 : 2002::/64

HOST B OpenVPN Client

OS   : Ubuntu 18.04
IP   : 2345::2/64
LAN2 : 2003::/64

Konfigurasi Server

echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
echo 1 > /proc/sys/net/ipv4/conf/default/forwarding
echo 1 > /proc/sys/net/ipv4/conf/tun0/forwarding
echo 1 > /proc/sys/net/ipv4/conf/enp0s3/forwarding
echo 1 > /proc/sys/net/ipv4/conf/enp0s8/forwarding
echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
echo 1 > /proc/sys/net/ipv6/conf/default/forwarding
echo 1 > /proc/sys/net/ipv6/conf/tun0/forwarding
echo 1 > /proc/sys/net/ipv6/conf/enp0s3/forwarding
echo 1 > /proc/sys/net/ipv6/conf/enp0s8/forwarding

atau

vi /etc/sysctl.conf
net.ipv4.ip_forward=1
net.ipv4.conf.all.forwarding=1
net.ipv6.conf.all.forwarding=1
net.ipv6.conf.default.forwarding=1

sysctl -p

ifconfig enp0s3 192.168.0.239 netmask 255.255.255.0
ifconfig enp0s8 10.10.10.1 netmask 255.255.255.0
ip addr add 2002::1/64 dev enp0s8

Tambahan di konfigurasi /etc/openvpn/server.conf

ifconfig 10.8.0.1 255.255.255.0
server 10.8.0.0 255.255.255.0
tun-ipv6
server-ipv6 2345::/64
push tun-ipv6
route-ipv6 2003::/64
client-config-dir client

Tambahan di /etc/openvpn/client

File: client   # tergantung username client.ovpn

ifconfig-push 10.8.0.2 255.255.255.0     # paksa IP static di client untuk memudahkan routing
push "route 10.10.10.0 255.255.255.0"    # paksa routing ke upstream
iroute 10.10.20.0 255.255.255.0          # internal routing ke arah
#
ifconfig-ipv6-push 2345::2 2345::1       # set IPv6 interface client
push "route 2000::/3"                    # push tabel routing
iroute-ipv6 2003::/64                    # set internal routing ke client LAN, harus sesuai dengan yg di server.conf

Konfigurasi Client Gateway

echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
echo 1 > /proc/sys/net/ipv4/conf/default/forwarding
echo 1 > /proc/sys/net/ipv4/conf/tun0/forwarding
echo 1 > /proc/sys/net/ipv4/conf/enp0s3/forwarding
echo 1 > /proc/sys/net/ipv4/conf/enp0s8/forwarding
echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
echo 1 > /proc/sys/net/ipv6/conf/default/forwarding
echo 1 > /proc/sys/net/ipv6/conf/tun0/forwarding
echo 1 > /proc/sys/net/ipv6/conf/enp0s3/forwarding
echo 1 > /proc/sys/net/ipv6/conf/enp0s8/forwarding

atau

vi /etc/sysctl.conf
net.ipv4.ip_forward=1
net.ipv4.conf.all.forwarding=1
net.ipv6.conf.all.forwarding=1
net.ipv6.conf.default.forwarding=1

sysctl -p

Firewall atau NAT

Firewall jangan di pasang, jika kita ingin membuka semua client ke Internet.

agar lebih aman menggunakan firewall (experimental)

ipt6tables -P FORWARD DROP
ip6tables -A FORWARD -s 2003::/64 -d ::/0 -m comment --comment "allow outgoing traffic from local ipv6 range" -j ACCEPT
ip6tables -A FORWARD -m state --state RELATED,ESTABLISHED -m comment --comment "Accept established" -j ACCEPT
ip6tables -A INPUT -i enp0s8 -j ACCEPT
#
# ijinkan akses tertentu ke internal
ip6tables -A FORWARD -d 2003::c01d/64 -m comment --comment "let internet conrtol airco" -j ACCEPT

# Allow traffic initiated from VPN to access LAN
ip6tables -I FORWARD -i tun0 -o enp0s8 -m conntrack --ctstate NEW -j ACCEPT
# Allow traffic initiated from LAN to access "the world"
ip6tables -I FORWARD -i enp0s8 -o tun0 -m conntrack --ctstate NEW -j ACCEPT
# Allow established traffic to pass back and forth
ip6tables -I FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

Jika firewall juga gagal, tampaknya kita akan stuck dengan NAT

ip6tables -t nat -A POSTROUTING -s 2003::/64 -o tun0 -j MASQUERADE

Konfigurasi Interface

Konfigurasi interface

sudo su
ifconfig enp0s3 192.168.0.163 netmask 255.255.255.0
ifconfig enp0s8 10.10.20.1 netmask 255.255.255.0
ip addr add 2003::1/64 dev enp0s8

Install radvd

Edit /etc/radvd.conf:

# file: /etc/radvd.conf
interface enp0s8
{ 
  AdvSendAdvert on; 
  prefix 2003::/64 
  {
    AdvOnLink on;
    AdvAutonomous on;
  }; 
};

Install

apt install radvd

TIDAK ADA Tambahan konfigurasi di client.ovpn. Pastikan setup interface BENAR. Pastikan setup routing BENAR.

ip route show
ip -6 route show
route -n

Referensi

Pranala Menarik

OpenVPN