Problem routing traffic

Question

Hello,   
I've partially followed this guide  
https://aws.amazon.com/blogs/aws/new-vpc-ingress-routing-simplifying-integration-of-third-party-appliances/  
which explains how to route all traffic going through an internet gateway to a device (appliance), which then forwards it to the final destination (application).  
However, when I try to SSH to the "application", the traffic never reaches. If, instead, I remove the routing through the intermediate device, it all works normally.  
I'm trying to understand what could be the cause of this.  
Here is the exact setup:  
  
Internet gateway route table:  
10.0.0.0/16	local  
10.0.1.0/24      network_interface_appliance  
Appliance route table  
10.0.0.0/16      local  
0.0.0.0 /0         internet-gateway  
Application route table  
10.0.0.0/16      local  
0.0.0.0/0          network_interface_appliance  
  
The appliance is on subnet 10.0.0.0/24 and the application on 10.0.1.0/24  
  
The appliance has the ip forwarding as expected:  
sudo sysctl -w net.ipv4.ip_forward=1  
sudo sysctl -w net.ipv6.conf.all.forwarding=1  
  
When I try to ssh, I get a connectio timeout  
Thank you in advance for any help

EddyMercury · Answer

I had forgotten to remove the destination check.  
This can be done either using   
```  
aws ec2 modify-instance-attribute --region $AWS_REGION \  
                         --no-source-dest-check        \  
                         --instance-id $APPLIANCE_ID  
```  
or in the console -> actions -> networking -> Change source/dest check   
Note: the instance must be stopped when applying this modification.

Problem routing traffic

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