GRE tunnel on a linux system using DNAT

## CREATE GRE TUNNEL

modprobe ip_gre echo 1 > /proc/sys/net/ipv4/ip_forward ip tu add zen mode gre remote 10.66.63.5 local 10.66.63.21 ttl 128 ip ad ad dev zen 172.17.0.41 peer 172.17.0.42/30 ip li set zen up #iptables -I POSTROUTING -o zen -j MASQUERADE ip tu ls zen ip ad ls zen ping 172.17.0.42 -c 5

### IPTABLE RULE TO FORWARD TRAFFIC THROUGH GRE iptables -F

iptables -I OUTPUT -t nat -p tcp -s 10.37.144.130 -m multiport --dport 80,443,9401 -j DNAT --to 172.17.0.58