#!/bin/bash -x
PORT="$1"
shift

if [ -z "$PORT" ] || ! [ "$PORT" -gt 0 ]; then
	echo "'$PORT' is not a valid port number"
	exit 1
fi

# basic cleanup/setup
C=sshuttle-$PORT
iptables -t nat -D OUTPUT -j $C
iptables -t nat -F $C
iptables -t nat -X $C

if [ -z "$*" ]; then
    # just delete existing rules
    exit 0
fi
iptables -t nat -N $C
iptables -t nat -I OUTPUT 1 -j $C
iptables -t nat -D $C -j REDIRECT -p tcp --to-ports $PORT

# create new subnet entries
for subnet in "$@"; do
	iptables -t nat -A $C -j REDIRECT --dest "$subnet" -p tcp \
		--to-ports "$PORT"
done