.install SSH server so that the PC Linux gateaway accessable from other computer:

# apt-get install openssh-server

# /etc/init.d/ssh restart


. edit file /etc/network/interfaces. Make sure the content of the file is: (WAN1 : 10.0.148.48, WAN2:192.168.1.222, LAN:192.168.0.222)

auto eth0
iface eth0 inet static
address 10.0.148.48
netmask 255.255.255.0

auto eth1
iface eth1 inet static
address 192.168.0.222
netmask 255.255.255.0

auto eth2
iface eth2 inet static
address 192.168.1.222
netmask 255.255.255.0

. fill the file of /etc/iproute2/rt_tables with  adsl table, wirelessisp, dan internet to simplefied iproute2 job. Example of file content:

120 adsl
121 wirelessisp
123 internet

. Make script to start and control iproute2 to turn ON load balancing. The script can be place at /etc/rc.local so it will automaticly start on booting. Example of the script:

# activate interface/sbin/ip link set lo up

/sbin/ip link set eth0 up
/sbin/ip link set eth1 up
/sbin/ip link set eth2 up

# flush/clear existing routing table
/sbin/ip route flush table adsl
/sbin/ip route flush table wirelessisp
/sbin/ip route flush table internet

# enter the information of ip address and broadcast every interface
/sbin/ip addr add 127.0.0.1/8 brd 127.0.0.255 dev lo
/sbin/ip addr add 192.168.1.222/24 brd 192.168.1.255 dev eth2
/sbin/ip addr add 10.0.148.48/24 brd 10.0.148.255 dev eth0
/sbin/ip addr add 192.168.0.222/24 brd 192.168.0.255 dev eth1

# Enter the routing table to LAN
/sbin/ip route add 127.0.0.0/8 dev lo
/sbin/ip route add 192.168.0.0/24 dev eth1

# give priority to each table
/sbin/ip rule add prio 10 table main
/sbin/ip rule add prio 20 table adsl
/sbin/ip rule add prio 30 table wirelessisp
/sbin/ip rule add prio 40 table internet

# delete routing to the default gateway
/sbin/ip route del default table main
/sbin/ip route del default table adsl
/sbin/ip route del default table wirelessisp
/sbin/ip route del default table internet

# make a routing table to ADSL gateaway
/sbin/ip rule add prio 20 from 192.168.1.0/24 table adsl
/sbin/ip route add default via 192.168.1.1 dev eth2 src 192.168.1.222 \
proto static table adsl
/sbin/ip route append prohibit default table adsl metric 1 proto static

# make a routing table to Wireless ISP
/sbin/ip rule add prio 30 from 10.0.148.0/24 table wirelessisp
/sbin/ip route add default via 10.0.148.254 dev eth0 src 10.0.148.48 \
proto static table wirelessisp
/sbin/ip route append prohibit default table wirelessisp metric 1 proto static

# setup load balancing with 2 gateway to the Internet
/sbin/ip rule add prio 40 table internet
/sbin/ip route add default proto static table internet \
nexthop via 192.168.1.1 dev eth2 weight 1 \
nexthop via 10.0.148.254 dev eth0 weight 1

. Lastly, make a script to do NAT job to both WAN interface to internet. Script can be place at  /etc/rc.local so it will run automatically upon booting. Example script:

# make sure the linux pc can foward ip packet
/bin/echo 1 > /proc/sys/net/ipv4/ip_forward

# clear iptables content
/sbin/iptables -F
/sbin/iptables -P INPUT DROP
/sbin/iptables -A INPUT -i eth1 -j ACCEPT
/sbin/iptables -A INPUT -m state --state ESTABLISHED, RELATED -j ACCEPT
/sbin/iptables -A INPUT -p tcp -i eth0 -j REJECT --reject-with tcp-reset
/sbin/iptables -A INPUT -p tcp -i eth2 -j REJECT --reject-with tcp-reset
/sbin/iptables -A INPUT -p udp -i eth0 -j REJECT --reject-with icmp-port-unreachable
/sbin/iptables -A INPUT -p udp -i eth2 -j REJECT --reject-with icmp-port-unreachable

# do the NAT for eth0 and eth2 interface
/sbin/iptables -t nat -A POSTROUTING -o eth2 -j SNAT --to 192.168.1.222
/sbin/iptables -t nat -A POSTROUTING -o eth0 -j SNAT --to 10.0.148.48