default_routes.sh

#!/bin/sh

# credit: http://kindlund.wordpress.com/2007/11/19/configuring-multiple-default-routes-in-linux/ "Configuring Multiple Default Routes in Linux"

start() {
  start_iface
  start_vlans
  start_addresses
  start_routes
  configure_resolv
}

stop() {
  stop_routes
  stop_addresses
  stop_vlans
  stop_iface
}

restart() {
  stop
  start
}

start_iface() {
  ip link set eth0 up
}

stop_iface() {
  ip link set eth0 down
}

start_vlans() {
  vconfig add eth0 10
  ip link set eth0.10 up
  vconfig add eth0 20
  ip link set eth0.20 up
  vconfig add eth0 30
  ip link set eth0.30 up
}

stop_vlans() {
  ip link set eth0.10 down
  vconfig rem eth0.10
  ip link set eth0.20 down
  vconfig rem eth0.20
  ip link set eth0.30 down
  vconfig rem eth0.30
}

start_addresses() {
  ip address add 10.1.1.10/24 dev eth0
  ip address add 10.2.2.20/24 dev eth0.10
  ip address add 10.3.3.30/24 dev eth0.20
  ip address add 10.4.4.40/24 dev eth0.30
}

stop_addresses() {
  ip address flush eth0
  ip address flush eth0.10
  ip address flush eth0.20
  ip address flush eth0.30
}

start_routes() {

  rt_tables=/etc/iproute2/rt_tables
  echo '255 local'   >  $rt_tables
  echo '1 main'    >> $rt_tables
  echo '253 default' >> $rt_tables
  echo '0 unspec'    >> $rt_tables

  # Define tables
  echo '1 rt1' >> $rt_tables
  ip route add 10.1.1.0/24 dev eth0 src 10.1.1.10 table rt1
  ip route add default via 10.1.1.1 dev eth0 table rt1
  ip rule add from 10.1.1.10/32 table rt1
  ip rule add to 10.1.1.10/32 table rt1

  echo '2 rt2' >> $rt_tables
  ip route add 10.2.2.0/24 dev eth0.10 src 10.2.2.20 table rt2
  ip route add default via 10.2.2.1 dev eth0.10 table rt2
  ip rule add from 10.2.2.20/32 table rt2
  ip rule add to 10.2.2.20/32 table rt2

  echo '3 rt3' >> $rt_tables
  ip route add 10.3.3.0/24 dev eth0.20 src 10.3.3.30 table rt3
  ip route add default via 10.3.3.1 dev eth0.20 table rt3
  ip rule add from 10.3.3.30/32 table rt3
  ip rule add to 10.3.3.30/32 table rt3

  echo '4 rt4' >> $rt_tables
  ip route add 10.4.4.0/24 dev eth0.30 src 10.4.4.40 table rt4
  ip route add default via 10.4.4.1 dev eth0.30 table rt4
  ip rule add from 10.4.4.40/32 table rt4
  ip rule add to 10.4.4.40/32 table rt4

  ip route add default via 10.1.1.1
}

stop_routes() {
  ip route flush all
  ip rule delete from 10.1.1.10
  ip rule delete to 10.1.1.10
  ip rule delete from 10.2.2.20
  ip rule delete to 10.2.2.20
  ip rule delete from 10.3.3.30
  ip rule delete to 10.3.3.30
  ip rule delete from 10.4.4.40
  ip rule delete to 10.4.4.40
}

configure_resolv() {
  resolv=/etc/resolv.conf
  echo 'domain local'         > $resolv
  echo 'search local'        >> $resolv
  echo 'nameserver 10.1.1.1' >> $resolv
  echo 'nameserver 8.8.8.8'  >> $resolv
}

case "$*" in
  start)
    start
    ;;
  stop)
    stop
    ;;
  restart|reload|force-reload)
    restart
    ;;
  *)
    echo "Usage: $0 {start|stop|restart}"
esac