I have an EC2 instance that connects to a VPN and another instance in the same VPC that emmits traffic to that VPN
So the topology is something like this: 
- The instance at 172.1.0.1 can connect to the remote VPN (192.168.1.0/24) without any issues.
- The instances within the VPC can connect to each other.
- Instances i-aaaa and i-bbbb cannot connecto to machines in 192.168.1.0/24
Current configuration looks like this:
- The route table in the VPC has an entry for 192.168.1.0/24 via i-0000
- The sec group allows all traffic within the security group
- All instances in the VPC are in the same security group
I have configured flow logs in the VPC and notice that I can see traffic going out of the ENI at i-bbbb but there is no traffic in the ENI at i-0000
Also, packet capture in i-0000 does not show any packet comming from any of the other instances with dst to 192.168.1.0/24
So this raises some questions:
- Would AWS drop packets because they are not in the same CIDR as the rest of the VPC? (My guess is not)
- How can I troubleshoot where are packets being dropped? Everything suggests that packets are dropped within the VPC by AWS
- What else can I try to make it work?
Thanks!
