NAT Gateway issues

Available in VPC

You might run into the following problems when using VPC. Find out causes and possible solutions.

Adjusting Timeout

I am using NAT Gateway on VPC platform because I need to use SSH tunneling with an external public server. However, the disconnection occurs after 2 minutes, even when I change the Timeout setting. SSH tunneling with the same external public server operates normally for public servers within Classic.

Cause and solution

NAT Gateway session Timeout differs on Classic and VPC platforms. NAT Gateway session Timeout on VPC platform is 120 seconds and is not adjustable.

Route Table addition error

After creating NAT Gateway, I received the message that it cannot be configured when adding to Route Table.

Cause

Error might occur if the associated Subnet in Route Table contains NAT Subnet.

Solution

The following is the solution to resolve Route Table configuration errors:

1. Create a separate Route Table to handle NAT Gateway.
2. Register NAT Subnet with the related Subnet.
3. Add the configuration related to NAT Gateway to the Route Table you want to modify.

Configuration cannot be done in the Public routing table if the routing table has a subnet related to NAT Gateway

After creating multiple servers, I want to set the destination servers to communicate with a single IP. Still, I can't put it in the Public routing table when the routing table has a subnet for NAT Gateway related to it.

Cause

In the related subnet setting in the Route Table, you must add the server's Subnet that will communicate through NAT Gateway public IP, not the subnet for NAT Gateway.

Solution

Set up the Route Table as follows:

• Destination: The IP or IP band where the server wants to communicate through NAT Gateway public IP
  • If the same band has already been added, you can't add it.
  • However, if you selected the Subnet type as 'Public' when creating the Route Table, 0.0.0.0/0, IGW, and INTERNET GATEWAY are added. Therefore, if you select NATGW for the Target Type, you must set it to a specific IP band. If you want to set the destination to 0.0.0.0/0, delete the already registered INTERNET GATEWAY setting or change it to a specific IP band.
• Target Type: NATGW
• Target Name: Select the NAT Gateway name you created