0. local.conf

[peername]
proto = nacltai
proto_publickey = REMOTE_PUBKEY
proto_privatekey = LOCAL_PRIKEY
local = tuntap
local_interface = tunnel
peer = udp
peer_remoteaddr = REMOTE_IP
peer_remoteport = 8000
peer_localaddr = 0.0.0.0
peer_localport = 8000

1. remote.conf

[peername]
proto = nacltai
proto_publickey = LOCAL_PUBKEY
proto_privatekey = REMOTE_PRIKEY
local = tuntap
local_interface = tunnel
peer = udp
peer_localaddr = REMOTE_IP
peer_localport = 8000
peer_remotefloat = 1

2. remote.sh

sudo ifconfig tunnel 10.8.0.1/24
sudo ifconfig tunnel mtu 1440
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
iptables -A FORWARD -i eth0 -o tunnel -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i tunnel -o eth0 -j ACCEPT

3. local.sh

ifconfig tunnel 10.8.0.2/24
ifconfig tunnel mtu 1440
route del default
route add 106.186.124.182 gw 10.0.1.1  # change 10.0.1.1 into your gateway IP for example 192.168.1.1
route add default gw 10.8.0.1
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o tunnel -j MASQUERADE
iptables -A FORWARD -i tunnel -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i eth0 -o tunnel -j ACCEPT
iptables -t mangle -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1400

4. local routing

$ ifconfig tunnel
tunnel    Link encap:Ethernet  HWaddr c6:02:a3:f9:78:c2  
          inet addr:10.8.0.2  Bcast:10.8.0.255  Mask:255.255.255.0

$ netstat -nr
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         10.8.0.1        0.0.0.0         UG        0 0          0 tunnel
10.0.1.0        0.0.0.0         255.255.255.0   U         0 0          0 eth0
10.8.0.0        0.0.0.0         255.255.255.0   U         0 0          0 tunnel
REMOTE_IP       10.0.1.1        255.255.255.255 UGH       0 0          0 eth0
REMOTE_IP       0.0.0.0         255.255.255.255 UH        0 0          0 tunnel

5. remote routing

$ ifconfig tunnel
tunnel    Link encap:Ethernet  HWaddr 66:a0:23:f1:fa:9e  
          inet addr:10.8.0.1  Bcast:10.8.0.255  Mask:255.255.255.0

$ iptables -L -n -t nat -v

Chain POSTROUTING (policy ACCEPT 1222K packets, 82M bytes)
 pkts bytes target     prot opt in     out     source               destination         
3929K  244M MASQUERADE  all  --  *      eth0    0.0.0.0/0            0.0.0.0/0           
    0     0 MASQUERADE  all  --  *      eth0    0.0.0.0/0            0.0.0.0/0