How to add custom route via EC2?

Question

I need to route certain traffic via site-to-site VPN. This trivial thing doesn't work for me in AWS, while works fine in my test on-prem environment.
For instance:
- I need to route traffic to 111.111.111.111/32 via 10.10.10.11
- I tried both adding this route to 10.10.10.10, and adding it into the VPC routing table - no results. I.e. I. don't see packets to 111.111.111.111 coming to 10.10.10.11. (I checked both using network sniffer on 10.10.10.11 and using AWS Flow logs).

Any ideas?
TIA,
Vitaly

Answer

You should do this by routing to an AWS object that has the IP...  i.e. the eni-XXXX that has the 10.10.10.11 IP assigned to it.

AWS route tables need to point objects like ENIs, TGWs, PCXs and not IP addresses.

Answer

I  found the issue - it was the default "Source/dest. check" == True in the ENI of my VPN box.

How to add custom route via EC2?

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