ip tunnel add gre1 mode gre local S1-ip remote main-ip ttl 255
ip addr add 192.168.10.1/30 dev gre1
ip link set gre1 up

ip tunnel add gre2 mode gre local S2-ip remote main-ip ttl 255
ip addr add 192.168.168.1/24 dev gre2
ip link set gre2 up

ip tunnel add gre1 mode gre local main-ip remote S1-ip ttl 255
ip addr add 192.168.10.2/30 dev gre1
ip link set gre1 up

ip tunnel add gre2 mode gre local main-ip remote S2-ip ttl 255
ip addr add 192.168.168.2/30 dev gre2
ip link set gre2 up
echo 200 grea >> /etc/iproute2/rt_tables
echo 201 greb >> /etc/iproute2/rt_tables

ip rule add from 192.168.10.0/30 table grea
ip rule add from 192.168.168.0/30 table greb


ip route add default via 192.168.10.1 table gre1
ip route add default via 192.168.168.1 table gre2