Selective VPN routing in Tomato

wan-up

# This code goes in the WAN UP section of the Tomato GUI.
#
#  To list the current rules on the router, issue the command:
#      iptables -t mangle -L PREROUTING
#
#  Flush/reset all the rules to default by issuing the command:
#      iptables -t mangle -F PREROUTING
#
#
# First it is necessary to disable Reverse Path Filtering on all
# current and future network interfaces:
#
for i in /proc/sys/net/ipv4/conf/*/rp_filter ; do
  echo 0 > $i
done
 
#
# Delete and table 100 and flush any existing rules if they exist.
#
ip route flush table 100
ip route del default table 100
ip rule del fwmark 1 table 100
ip route flush cache
iptables -t mangle -F PREROUTING
 
#
# Copy all non-default and non-VPN related routes from the main table into table 100.
# Then configure table 100 to route all traffic out the WAN gateway and assign it mark "1"
#
# Assumption: the OpenVPN tunnel is named "tun11".
#
#
ip route show table main | grep -Ev ^default | grep -Ev tun11 \
  | while read ROUTE ; do
      ip route add table 100 $ROUTE
done
ip route add default table 100 via $(nvram get wan_gateway)
ip rule add fwmark 1 table 100
ip route flush cache
 
 
#
# Define the routing policies for the traffic. The rules will be applied in the order that they
# are listed. In the end, packets with MARK set to "0" will pass through the VPN. If MARK is set
# to "1" it will bypass the VPN.
#
 
# By default all traffic bypasses the VPN
iptables -t mangle -A PREROUTING -i br0 -j MARK --set-mark 1
 
# p2p / usenet specifically uses the VPN
iptables -t mangle -A PREROUTING -i br0 -m multiport --dport 119,563 -j MARK --set-mark 0
iptables -t mangle -A PREROUTING -i br0 -m multiport --dport 6681-6889 -j MARK --set-mark 0