Site2Cloud With Customized SNAT

This tech note describes how to create a Site2Cloud connection between two VPCs by using a VGW and an Aviatrix gateway. The Aviatrix gateway also serves as a source NAT device and translates source IP address of the traffic initiated from a peering VPC to an IP address selected by users.

Environment Requirements

There are two VPCs as illustrated in the diagram below. VPC-1’s CIDR is and VPC-2’s CIDR is The Site2Cloud connection is between a VGW in VPC-1 and an Aviatrix gateway in VPC-2.


We will also configure customized SNAT at the Aviatrix gateway, which translates the source IP of traffic initiated from VPC-1 ( to a user selected IP address ( in this example). In this way, VPC-2 VMs will see all packets from VPC-1 with the same source IP address (

Steps to Configure Site2Cloud Connection and SNAT

  • Step 1: Install an Aviatrix gateway in VPC-2.

Download and install the Aviatrix Gateways by following the instructions in this document

Don’t select “Enable SNAT” when creating the new gateway in VPC-2.

  • Step 2: Create a Site2Cloud connection between a VGW in VPC-1 and an Aviatrix gateway in VPC-2


In the Aviatrix terminology, Site2Cloud is the name of the feature that enables connections from one site (or datacenter) to other sites (including cloud environments).

Please follow the instructions in this document to create the Site2Cloud connection.

  • Step 3: Update VPC-1 Route Tables at AWS portal

Update VPC-1 route tables to ensure that traffic destinating to VPC-2 ( takes the VGW as “Target”:

Field Value
Target VGW ID
  • Step 4: Configure Customized SNAT at the Aviatrix gateway

a. Log into the Controller and go to “Gateway” page.

b. Select the Aviatrix gateway created in VPC-2.


c. Click “Edit” button and go to “Source NAT” section.

d. Select “Customized SNAT”.

e. Configure the following SNAT rule.

Field Value
Source CIDR VPC-1 CIDR (
Source Port Leave it blank
Destination CIDR VPC-2 CIDR (
Destination Port Leave it blank
Protocol all
Interface eth0
Mark Leave it blank
SNAT IPs User selected IP (
SNAT Port Leave it blank


f. Click “Save” and “Enable SNAT” buttons

Test site2cloud Connection and SNAT

a. Go to the “Site2Cloud” page and verify that the Site2Cloud connection status is “Up”.


b. Pings from an opensource OS VM in VPC-1 to another opensource OS version VM in VPC-2.

c. Turn on “tcpdump icmp -n” at the opensource OS VM in VPC-2. Verify the source IP of the pings is