AWS - pfsense: Site-to-site VPN using static routes

February 22, 2022

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In this post I willll show you how to configure a VPN between pfSense and AWS using static routes.

To create a VPN on AWS side you need the following Components:

Customer Gateway - This is represent the on-premise side of the vpn
virtual private gateway - this is a router in the aws
vpn Connection
virtual priveta cloud

vpc -> virtual private gateway -> vpn Connection -> Customer Gateway

vpn infra

We need to create this components and connect them to each other.

Customer Gateway

# set to your own public ip
export CLIENT_PUBLIC_IP=1.2.3.4

# Create the customer gateway using the following AWS command:
aws ec2 create-customer-gateway --type ipsec.1 --public-ip $CLIENT_PUBLIC_IP

{
    "CustomerGateway": {
        "CustomerGatewayId": "cgw-0e11f167",
        "IpAddress": "1.2.3.4",
        "State": "available",
        "Type": "ipsec.1",
        "BgpAsn": "65000"
    }
}

export CUSTOMER_GATEWAY=cgw-0e11f167

Create a Virtual Private Gateway

Create a target gateway and attach it to your VPC network.

# Create a virtual private gateway with a specific AWS-side ASN:
aws ec2 create-vpn-gateway --type ipsec.1

{
    "VpnGateway": {
        "AmazonSideAsn": 64512,
        "State": "available",
        "Type": "ipsec.1",
        "VpnGatewayId": "vgw-9a4cacf3",
        "VpcAttachments": []
    }
}

export VPN_GATEWAY_ID=vgw-9a4cacf3
export VPC_ID=

# Attach the virtual private gateway to your VPC network:
aws ec2 attach-vpn-gateway --vpn-gateway-id $VPN_GATEWAY_ID --vpc-id $VPC_ID

Create a VPN Connection

export AWS_TIP=169.254.0.0/30
# random string for secret
export SHARED_SECRET=g23r8gr7grg23r8g2fnmf
# my network on the on-premise side
export ONPREM_NETWORK=192.168.1.0/24

aws ec2 create-vpn-connection \
    --type ipsec.1 \
    --customer-gateway-id $CUSTOMER_GATEWAY \
    --vpn-gateway-id $VPN_GATEWAY_ID \
    --options TunnelOptions="[{TunnelInsideCidr=$AWS_TIP,PreSharedKey=$SHARED_SECRET}]",StaticRoutesOnly=true,LocalIpv4NetworkCidr=$ONPREM_NETWORK

{
    "VpnConnection": {
        "CustomerGatewayConfiguration": "...configuration information...",
        "CustomerGatewayId": "cgw-0e11f167",
        "Category": "VPN",
        "State": "pending",
        "VpnConnectionId": "vpn-123123123123abcab",
        "VpnGatewayId": "vgw-9a4cacf3",
        "Options": {
            "EnableAcceleration": false,
            "StaticRoutesOnly": true,
            "LocalIpv4NetworkCidr": "192.168.1.0/24",
            "RemoteIpv4NetworkCidr": "0.0.0.0/0",
            "TunnelInsideIpVersion": "ipv4",
            "TunnelOptions": [
                {
                    "OutsideIpAddress": "203.0.113.3",
                    "TunnelInsideCidr": "169.254.0.0/30",
                    "PreSharedKey": "g23r8gr7grg23r8g2fnmf"
                },
                {}
            ]
        },
        "Routes": [],
        "Tags": []
    }
}

In the TunnelOptions you can configure other options of the vpn like:

IKEVersions=[{Value=ikev2})
Phase2DHGroupNumbers=[{Value=15})
Phase1DHGroupNumbers=[{Value=15})
Phase2IntegrityAlgorithms=[{Value=SHA2-256})
Phase1IntegrityAlgorithms=[{Value=SHA2-256})
Phase2EncryptionAlgorithms=[{Value=AES256-GCM-16})
Phase1EncryptionAlgorithms=[{Value=AES256-GCM-16})

Configure Routing

aws ec2 create-route --route-table-id rtb-89012345678901234 \
--destination-cidr-block 172.31.0.0/16 \
--transit-gateway-id tgw-56789012345678901

Download the configuration file

After you create the Site-to-Site VPN connection, you can download a sample configuration file to use for configuring the customer gateway device.

The configuration file is an example only and might not match your intended Site-to-Site VPN connection settings entirely. It specifies the minimum requirements for a Site-to-Site VPN connection of AES128, SHA1, and Diffie-Hellman group 2 in most AWS Regions, and AES128, SHA2, and Diffie-Hellman group 14 in the AWS GovCloud Regions. It also specifies pre-shared keys for authentication. You must modify the example configuration file to take advantage of additional security algorithms, Diffie-Hellman groups, private certificates, and IPv6 traffic.