add_policy_route.sh

#!/bin/sh
perl -v > /dev/null || exit 1
m()
{
        curl -s http://169.254.169.254/latest/meta-data/network/interfaces/macs/$1
}

for mac in `m`
do
        dev=`m $mac/device-number`
        subnet=`m $mac/subnet-ipv4-cidr-block`
        gw=`echo $subnet | perl -pe 's#/.+##; @ip=split(/\./); $ip[3]++ ; $_=join(".",@ip)'`
        ip route flush table 100$dev
        ip route add table 100$dev to $subnet dev eth$dev
        ip route add table 100$dev to default via $gw dev eth$dev
        ip rule add from $subnet table 100$dev priority 100$dev
done
ip route flush cache