> ## Documentation Index
> Fetch the complete documentation index at: https://docs.aviatrix.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Site2Cloud With Customized SNAT

> This document demonstrates 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 IPs of traffic initiated from a peering VPC to an IP address selected by users.

This document demonstrates 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 IPs of
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. The VPC-1 CIDR is
10.0.0.0/16 and the VPC-2 CIDR is 172.19.0.0/16. The Site2Cloud connection
is between a VGW in VPC-1 and an Aviatrix gateway in VPC-2.

<img src="https://mintcdn.com/aviatrix-14b37c43/Gre8pdluiL7JmlpL/images/guides/connectivity/vpn/s2c-snat.png?fit=max&auto=format&n=Gre8pdluiL7JmlpL&q=85&s=31121917479f99d06835ad6f8f402ae9" alt="s2c-snat" width="1050" height="438" data-path="images/guides/connectivity/vpn/s2c-snat.png" />

You will also configure customized SNAT at the Aviatrix gateway, which
translates the source IP of traffic initiated from VPC-1 (10.0.0.0/16)
to a user selected IP address (192.168.1.10 in this example). This
way, VPC-2 VMs will see all packets from VPC-1 with the same source IP
address (192.168.1.10).

## Steps to Configure Site2Cloud Connection and SNAT

1. Install an Aviatrix gateway in VPC-2 by following [these instructions](https://legacy.docs.aviatrix.com/documentation/latest/network/spoke-gateway-about.html?expand=true).

2. Create an Unmapped external connection between the VGW in VPC-1 and the Aviatrix gateway in VPC-2.

   * [Static Route-Based](https://legacy.docs.aviatrix.com/documentation/latest/network/external-connection-create-static-route-based-unmapped.html)
   * [Static Policy-Based](https://legacy.docs.aviatrix.com/documentation/latest/network/external-connection-create-static-policy-based-unmapped.html)

   <Note>
     When creating the connection, select *Generic* for Remote Device Type.
   </Note>

3. Update VPC-1 Route Tables at AWS portal to ensure that traffic with VPC-2 (172.19.0.0/16) as the destination takes the VGW as "Target":

   | **Field**   | **Value**     |
   | ----------- | ------------- |
   | Destination | 172.19.0.0/16 |
   | Target      | VGW ID        |

4. Configure Customized SNAT at the Aviatrix gateway.

   a. In Aviatrix CoPilot, go to Cloud Fabric > Gateways > Spoke Gateways.

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

   c. On the Settings tab, expand *Network Address Translation (NAT)* section.

   d. Set Source NAT toggle *On*.

   e. Select *Customized SNAT*.

   f. Configure the following SNAT rule.

   | **Field**  | **Value**                       |
   | ---------- | ------------------------------- |
   | Src CIDR   | VPC-1 CIDR (10.0.0.0/16)        |
   | Src Port   | Leave it blank                  |
   | Dst CIDR   | VPC-2 CIDR (172.19.0.0/16)      |
   | Dst Port   | Leave it blank                  |
   | Protocol   | all                             |
   | Connection | None                            |
   | Mark       | Leave it blank                  |
   | SNAT IPs   | User selected IP (192.168.1.10) |
   | SNAT Port  | Leave it blank                  |

   <img src="https://mintcdn.com/aviatrix-14b37c43/Gre8pdluiL7JmlpL/images/guides/connectivity/vpn/s2c-snat2.png?fit=max&auto=format&n=Gre8pdluiL7JmlpL&q=85&s=ae29ff5ec9dfab3099a660e3371c2841" alt="s2c-snat2" width="2510" height="638" data-path="images/guides/connectivity/vpn/s2c-snat2.png" />

   g. Click *Save*.

   The rule appears in the table.

   h. Set *Apply Route Entry* toggle *On* to commit the rule.

### Test Site2Cloud Connection and SNAT

Use the following tools to test the connection and verify the source IP NAT to the IP selected.

* Go to Diagnostics > Cloud Routes > External Connections to verify that the external connection status is Up.

* Ping from an Ubuntu VM in VPC-1 to another Ubuntu VM in VPC-2.

* Turn on "tcpdump icmp -n" at the Ubuntu VM in VPC-2. Verify the
  source IP of the pings is 192.168.1.10.

## Related Topics

* <a href={"/docs/enterprise/" + "10.1" + "/guides/connectivity/vpn/spoke-gateway-snat-dnat"}>Using Customized SNAT and DNAT on Spoke Gateway</a>
* <a href={"/docs/enterprise/" + "10.1" + "/guides/connectivity/vpn/s2c-nat-overlapping"}>Site2Cloud with NAT to fix Overlapping VPC Subnets</a>