I have an Ubuntu 20.04 machine with 2 ethernet interfaces with 2 IP addresses each. It's an AWS EC2 instance and each of the 4 IP addresses has an EIP attached to it via NAT. Both interfaces connect to the same internal subnet. The setup looks like this:
EC2 Machine:
- eni1:
- private-IP1 -> public-IP1
- private-IP2 -> public-IP2
- eni2:
- private-IP3 -> public-IP3
- private-IP4 -> public-IP4
All 4 addresses are reachabale from the outside so that seems to be all fine. However for outgoing traffic currently always private-IP1 (and thus public-IP1) gets used. I want to specify that individual SSH users use specific IP addresses, so they'll come from the corresponding public IP when talking to services on the internet i.e.
user1 -> private-IP1
user2 -> private-IP2
user3 -> private-IP3
user4 -> private-IP4
What's the best way of achieving this result?