How to split outbound traffic by destination IPs on aws with static IP?

Question

Conditions are below.

And current setup.

To use static IP for outbound traffic, I setup EC2 instance as a NAT with below configuration,

iptables -t nat -A POSTROUTING -o eth0 -s 192.168.32.0/19 -j MASQUERADE

and configured Route Table to send all subnet traffic(0.0.0.0/0) to that EC2 instance's network interface.

But I have to use VPN if it has specific destination IP. How do I configure the network on AWS?

Do you really need a NAT instance? Can you just use an Elastic IP address? That won't scale past one instance, so a NAT instance is a better solution for scale. You can start with an elastic IP attached to one server and move it to a NAT server later. — Tim, Sep 28, 2018 at 18:40
Regarding the VPN, assume you have a VPG in your VPC? Just add a route table entry for the IPs that need to go down the VPN to the route table associated with your subnet(s). — Tim, Sep 28, 2018 at 18:41

Broco · Accepted Answer · 2018-09-28 10:50:31Z

3

You just have to add a route:

route add -net 192.168.100.0/24 gw 192.168.100.1 metric 1

In this example 192.168.100.0/24 is the VPN network and 192.168.100.1 is your VPN gateway.

answered Sep 28, 2018 at 10:50

Broco

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