#!/bin/sh
# $FreeBSD: releng/12.4/share/examples/netgraph/udp.tunnel 120612 2003-09-30 22:39:22Z julian $

# This script sets up a virtual point-to-point WAN link between
# two subnets, using UDP packets as the ``WAN connection.''
# The two subnets might be non-routable addresses behind a
# firewall.
#

# Here define the local and remote inside networks as well
# as the local and remote outside IP addresses and UDP port
# number that will be used for the tunnel.
#
LOC_INTERIOR_IP=192.168.1.1
LOC_EXTERIOR_IP=1.1.1.1
REM_INTERIOR_IP=192.168.2.1
REM_EXTERIOR_IP=2.2.2.2
REM_INSIDE_NET=192.168.2.0
UDP_TUNNEL_PORT=4028

# Create the interface node ``ng0'' if it doesn't exist already,
# otherwise just make sure it's not connected to anything.
# In FreeBSD, interfaces cannot be removed so it might already
# be there from before.
#
if ifconfig ng0 >/dev/null 2>&1; then
	ifconfig ng0 inet down delete >/dev/null 2>&1
	ngctl shutdown ng0:
else
	ngctl mkpeer iface dummy inet
fi

# Attach a UDP socket to the ``inet'' hook of the interface node
# using the ng_ksocket(4) node type.
#
ngctl mkpeer ng0: ksocket inet inet/dgram/udp

# Bind the UDP socket to the local external IP address and port
#
ngctl msg ng0:inet bind inet/${LOC_EXTERIOR_IP}:${UDP_TUNNEL_PORT}

# Connect the UDP socket to the peer's external IP address and port
#
ngctl msg ng0:inet connect inet/${REM_EXTERIOR_IP}:${UDP_TUNNEL_PORT}

# Configure the point-to-point interface
#
ifconfig ng0 ${LOC_INTERIOR_IP} ${REM_INTERIOR_IP}

# Add a route to the peer's interior network via the tunnel
#
route add ${REM_INSIDE_NET} ${REM_INTERIOR_IP}