Dual WAN with one as standby backup

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article need of major revision - one with dual wan as backup another simple round equalization

Contents

Dual WAN with one as standby backup

This tutorial explains how you can assign one (or more) of the LAN ports as an extra WAN port. There is another tutorial Dual-WAN_for_simple_round-robin_load_equalization which explains how you can load balance between the two WAN connections. In this case I did not want to load balance; but rather create a standby WAN connection.

Justification

I needed to configure backup WAN as standby as it is not an unlimited connection. I pay for the backup connections by Giga-Bytes used. My primary WAN connection is of unlimited type. I intend to switch to backup only when the primary one goes down.

Assumptions

I have assumed static IP addresses for both the WAN interfaces. Making them dynamic will require some changes (hint nvram set wan2_proto=dynamic) Also, I am assuming DNSMasq is used for DHCP and DNS. JFFS should be enabled if you want to save the WAN-connection switch scripts. Also, I am assuming that you have already configured the first WAN connection (tied to vlan1) using nvram or web interface.

Create an extra VLAN

First you need to create an extra VLAN. In this case we want to to remove the port 4 from vlan0 and add it to the new vlan2

nvram set vlan0ports="1 2 3 5*"
nvram set vlan2ports="4 5"
nvram set vlan2hwname=et0
nvram set wan2_ifnames=vlan2
nvram set wan2_ifname=vlan2
nvram set wan2_mtu=1500
nvram commit

You can confirm or perform the setting using the dd-wrt web interface

http://your_router_ip/Vlan.asp

Now you have created an extra VLAN (vlan2).

Bring up the vlan2 Interface

I found it easier to configure the interface using ifconfig in the startup script. Somehow nvram bindings for backup WAN interface IP address did not work. ifconfig does the job though.

 nvram set rc_startup='
 #!/bin/ash

 PATH="/sbin:/usr/sbin:/bin:/usr/bin:${PATH}"

 ifconfig vlan2 10.10.2.209 netmask 255.255.255.0

 ifconfig vlan2 up
 ' 

Replace 10.10.2.209 with your WAN2 IP address

You can also perform this operation via the web interface

http://your_router_ip/Diagnostics.asp

Ofcourse you will need a reboot for this to be effective

Configure NAT on vlan2

We want to make sure packets leaving vlan2 are NATed

 nvram set rc_firewall='
  iptables -t nat -A POSTROUTING -o vlan2 -j MASQUERADE
 '

Again the same Diagnostics.asp page can be used on the web interface


Ctreate scripts to do the connection switch

We switch the internet connection by switching the default route and DNS servers.

Here we will create 2 scripts in /jffs to switch from one WAN connection to the other

script to switch to wan1

put this in /jffs/activate.wan1

#!/bin/ash
nvram set wan_dns="10.10.1.10 10.10.1.11"
route delete default
route delete default
route add default gw 10.10.1.1 vlan1
echo "nameserver 10.10.1.10" > /tmp/resolv.dnsmasq
echo "nameserver 10.10.1.11" >> /tmp/resolv.dnsmasq
pr="$(ps | grep dnsmasq | grep -v grep| awk '{print $1}')"
kill -9 $pr
dnsmasq --conf-file /tmp/dnsmasq.conf &

Used kill -9; because not sure why -1 (HUP) didnt work.

Obviously 10.10.1.10 and 10.10.1.11 are DNS servers for WAN1 and 10.10.1.1 is the default gateway. Replace these values with your own settings for WAN1

And put this in /jffs/activate.wan2

#!/bin/ash
nvram set wan_dns="10.10.2.10 10.10.2.11"
route delete default
route delete default
route add default gw 10.10.2.1 vlan2
echo "nameserver 10.10.2.10" > /tmp/resolv.dnsmasq
echo "nameserver 10.10.2.11" >> /tmp/resolv.dnsmasq
pr="$(ps | grep dnsmasq | grep -v grep| awk '{print $1}')"
kill -9 $pr
dnsmasq --conf-file /tmp/dnsmasq.conf &

Obviously 10.10.2.10 and 10.10.2.11 are DNS servers for WAN2 and 10.10.2.1 is the default gateway. Replace these values with your own settings for WAN2

You can switch connection by running the respective script

Connect the cable

Connect the backup WAN cable to the ethernet port marked as "4" and reboot.

More to come

  1. Automation of connection switching with email notification
  2. Web interface to monitor and switch connection


Dual-WAN for simple round-robin load equalization

(copied from forum-posting by user aldoir Dual-WAN forum posting

You'll need to create a new VLAN, called vlan2.

Enter in the web interface, Settings/VLANs. Set Port 4 to a new VLAN.

Enter in the console, and do the following commands

commands to set VLANs

nvram set vlan0ports="1 2 3 5*"
nvram set vlan2ports="4 5"
nvram set vlan2hwname=et0
nvram commit

Here are the scripts I used to startup the interface. You need to call them in rc_firewall

wan2.firewall

//edit - dont like this bit, it doesnt seem to be for DHCP connection and looks like its for a static IP connection

#!/bin/sh
WAN2_IFNAME=vlan2
WAN2_IPADDR=10.0.0.2
WAN2_GATEWAY=10.0.0.1
WAN2_NETMASK=255.0.0.0
if [ "$(nvram get wan2_ipaddr)" != "$WAN2_IPADDR" ]; then
        nvram set wan2_ifname=$WAN2_IFNAME   
   nvram set wan2_ipaddr=$WAN2_IPADDR
   nvram set wan2_gateway=$WAN2_GATEWAY
   nvram set wan2_netmask=$WAN2_NETMASK
   nvram commit
fi
ifconfig $(nvram get wan2_ifname) up $(nvram get wan2_ipaddr) netmask $(nvram get wan2_netmask)

routes.firewall

#!/bin/sh
ip rule flush
ip rule add lookup main prio 32766
ip rule add lookup default prio 32767
ip rule add from $(nvram get wan_ipaddr) table 100 prio 100
ip rule add fwmark 0x100 table 100 prio 101
ip rule add from $(nvram get wan2_ipaddr) table 200 prio 200
ip rule add fwmark 0x200 table 200 prio 201
ip route flush table 100
ip route flush table 200
for TABLE in 100 200
do
   ip route | grep link | while read ROUTE
   do
      ip route add table $TABLE to $ROUTE
   done
done
ip route add table 100 default via $(nvram get wan_gateway)
ip route add table 200 default via $(nvram get wan2_gateway)

firewall.firewall

#!/bin/sh
#DD-WRT firewall rules
#BEGIN
#apply simple forward rules
for RULE in $(nvram get forward_spec)
do
   FROM=`echo $RULE | cut -d '>' -f 1`
   TO=`echo $RULE | cut -d '>' -f 2`
   STATE=`echo $FROM | cut -d ':' -f 2`
   PROTO=`echo $FROM | cut -d ':' -f 3`
   SPORT=`echo $FROM | cut -d ':' -f 4`
   DEST=`echo $TO | cut -d ':' -f 1`
   DPORT=`echo $TO | cut -d ':' -f 2`
   if [ "$STATE" = "on" ]; then
      if [ "$PROTO" = "both" ]; then
         #udp
         #iptables -A FORWARD -d $(nvram get wan2_ipaddr) -p udp --dport $SPORT -j ACCEPT
         iptables -A PREROUTING -t nat -p udp -d $(nvram get wan2_ipaddr) --dport $SPORT -j DNAT --to $DEST:$DPORT
         #tcp
         #iptables -A FORWARD -d $(nvram get wan2_ipaddr) -p tcp --dport $SPORT -j ACCEPT
         iptables -A PREROUTING -t nat -p tcp -d $(nvram get wan2_ipaddr) --dport $SPORT -j DNAT --to $DEST:$DPORT
      else
         #iptables -A FORWARD -d $(nvram get wan2_ipaddr) -p $PROTO --dport $SPORT -j ACCEPT
         iptables -A PREROUTING -t nat -p $PROTO -d $(nvram get wan2_ipaddr) --dport $SPORT -j DNAT --to $DEST:$DPORT
      fi
   fi
done
#apply range forward rules
for RULE in $(nvram get forward_port)
do
   FROM=`echo $RULE | cut -d '>' -f 1`
   TO=`echo $RULE | cut -d '>' -f 2`
   STATE=`echo $FROM | cut -d ':' -f 2`
   PROTO=`echo $FROM | cut -d ':' -f 3`
   SPORT=`echo $FROM | cut -d ':' -f 4`
   EPORT=`echo $FROM | cut -d ':' -f 5`

   if [ "$STATE" = "on" ]; then
      if [ "$PROTO" = "both" ]; then
         #udp
         #iptables -A FORWARD -d $(nvram get wan2_ipaddr) -p udp --dport $SPORT:$EPORT -j ACCEPT
         iptables -A PREROUTING -t nat -p udp -d $(nvram get wan2_ipaddr) --dport $SPORT:$EPORT -j DNAT --to $TO
         #tcp
         #iptables -A FORWARD -d $(nvram get wan2_ipaddr) -p tcp --dport $SPORT:$EPORT -j ACCEPT
         iptables -A PREROUTING -t nat -p tcp -d $(nvram get wan2_ipaddr) --dport $SPORT:$EPORT -j DNAT --to $TO
      else
         #iptables -A FORWARD -d $(nvram get wan2_ipaddr) -p $PROTO --dport $SPORT:$EPORT -j ACCEPT
         iptables -A PREROUTING -t nat -p $PROTO -d $(nvram get wan2_ipaddr) --dport $SPORT:$EPORT -j DNAT --to $TO
      fi
   fi
done
iptables -A PREROUTING -t nat -p icmp -d $(nvram get wan2_ipaddr) -j DNAT --to $(nvram get lan_ipaddr)
if [ $(nvram get remote_management) -eq 1 ]; then
      iptables -A PREROUTING -t nat -p tcp -d $(nvram get wan2_ipaddr) \
            --dport $(nvram get http_wanport) -j DNAT --to $(nvram get lan_ipaddr):$(nvram get http_lanport)
fi
if [ $(nvram get dmz_enable) -eq 1 ]; then
      DMZ_IP=$(nvram get lan_ipaddr | sed -r 's/[0-9]+$//')$(nvram get dmz_ipaddr)
      iptables -A PREROUTING -t nat -d $(nvram get wan2_ipaddr) -j DNAT --to $DMZ_IP
fi
iptables -A PREROUTING -t nat --dest $(nvram get wan2_ipaddr) -j TRIGGER --trigger-type dnat
iptables -A FORWARD -i $(nvram get wan2_ifname) -o $(nvram get lan_ifname) -j TRIGGER --trigger-type in
iptables -A PREROUTING -t mangle -i $(nvram get wan2_ifname) -j IMQ --todev 0
iptables -A PREROUTING -t mangle -i $(nvram get wan2_ifname) -j SVQOS_IN
iptables -A POSTROUTING -t mangle -o $(nvram get wan2_ifname) -j SVQOS_OUT
#DD-WRT END
#Save the gateway in the connection mark for new incoming connections
iptables -t mangle -A PREROUTING -i $(nvram get wan_ifname) -m conntrack --ctstate NEW -j CONNMARK --set-mark 0x100
iptables -t mangle -A PREROUTING -i $(nvram get wan2_ifname) -m conntrack --ctstate NEW -j CONNMARK --set-mark 0x200
# Save the gateway in the connection mark for new outgoing connections
iptables -t mangle -A POSTROUTING -o $(nvram get wan_ifname) -m conntrack --ctstate NEW -j CONNMARK --set-mark 0x100
iptables -t mangle -A POSTROUTING -o $(nvram get wan2_ifname) -m conntrack --ctstate NEW -j CONNMARK --set-mark 0x200
# Use the correct gateway for reply packets from the LAN
iptables -t mangle -A PREROUTING -i $(nvram get lan_ifname) -m conntrack --ctstate ESTABLISHED,RELATED -j CONNMARK  --restore-mark
# Use the correct gateway for reply packets from local connections
iptables -t mangle -A OUTPUT -m conntrack --ctstate ESTABLISHED,RELATED -j CONNMARK --restore-mark
#mask known packets to its source address
iptables -A POSTROUTING -t nat -m mark --mark 0x100 -j SNAT --to-source $(nvram get wan_ipaddr)
iptables -A POSTROUTING -t nat -m mark --mark 0x200 -j SNAT --to-source $(nvram get wan2_ipaddr)
#permit access to wan2
iptables -A POSTROUTING -t nat -j MASQUERADE -o $(nvram get wan2_ifname)
#restore-mark is done in PREROUTING. If restored again, will loose the outgoing marks
iptables -t mangle -D SVQOS_OUT -j CONNMARK --restore-mark 2> /dev/null
#iptables -t mangle -A PREROUTING -i $(nvram get lan_ifname) -m multiport -p tcp --dport 22,25,80,110,119,143,443,993,3389 -j MARK --set-mark 0x100
#use WAN1 for common navigation, WAN2 for P2P traffic and others
#iptables -t mangle -I PREROUTING -i $(nvram get lan_ifname) -s 192.168.1.100 -j MARK --set-mark 0x200
#iptables -t mangle -I PREROUTING -i $(nvram get lan_ifname) -s 192.168.1.100 -j LOG --log-prefix 'P2P: '
RP_PATH=/proc/sys/net/ipv4/conf
for IFACE in `ls $RP_PATH`; do
   echo 0 > $RP_PATH/$IFACE/rp_filter
done

Once everything works, you should use the command ' ip route equalize' (search with Google for the syntax) to balance the load, or do a -j MARK --set-mark 0xN00 via iptables to redirect your traffig to WAN1 (0x100) or WAN2 (0x200)

If you need further assistance, post in forums or PM-me

The firewall scripts does not yet implement the full DD-WRT firewall, only the basic port/range forwarding.

This is script works for both outgoing AND incoming connections (most scripts only treats outgoing), so you should be able to accept connections in both links simultaneous (eg. web in one and FTP in another).