site-to-site-vpn

This component provisions a Site-To-Site VPN with a target AWS VPC on one side of the tunnel. The other (customer) side can be any VPN gateway endpoint, e.g. a hardware device, other cloud VPN, etc.

AWS Site-to-Site VPN is a fully-managed service that creates a secure connection between your data center or branch office and your AWS resources using IP Security (IPSec) tunnels. When using Site-to-Site VPN, you can connect to both your Amazon Virtual Private Clouds (VPC) and AWS Transit Gateway, and two tunnels per connection are used for increased redundancy.

The component provisions the following resources:

• AWS Virtual Private Gateway (a representation of the AWS side of the tunnel)

• AWS Customer Gateway (a representation of the other (remote) side of the tunnel). It requires:

  • The gateway's Border Gateway Protocol (BGP) Autonomous System Number (ASN)
  • /32 IP of the VPN endpoint

• AWS Site-To-Site VPN connection. It creates two VPN tunnels for redundancy and requires:

  • The IP CIDR ranges on each side of the tunnel
  • Pre-shared Keys for each tunnel (can be auto-generated if not provided and saved into SSM Parameter Store)
  • (Optional) IP CIDR ranges to be used inside each VPN tunnel

• Route table entries to direct the appropriate traffic from the local VPC to the other side of the tunnel

Post-tunnel creation requirements

Once the site-to-site VPN resources are deployed, you need to send the VPN configuration from AWS side to the administrator of the remote side of the VPN connection. To do this:

1. Determine the infrastructure that will be used for the remote side, specifically:

• Vendor
• Platform
• Software Version
• IKE version

1. Log into the target AWS account
2. Go to the "VPC" console
3. On the left navigation manu, go to Virtual Private Network > Site-to-Site VPN Connections
4. Select the VPN connection that was created via this component
5. On the top right, click the Download Configuration button
6. Enter the information you obtained and click Download
7. Send the configuration file to the administrator of the remote side of the tunnel

Usage

Stack Level: Regional

components:
  terraform:
    site-to-site-vpn:
      metadata:
        component: site-to-site-vpn
      vars:
        enabled: true
        name: "site-to-site-vpn"
        vpc_component_name: vpc
        customer_gateway_bgp_asn: 65000
        customer_gateway_ip_address: 20.200.30.0
        vpn_gateway_amazon_side_asn: 64512
        vpn_connection_static_routes_only: true
        vpn_connection_tunnel1_inside_cidr: 169.254.20.0/30
        vpn_connection_tunnel2_inside_cidr: 169.254.21.0/30
        vpn_connection_local_ipv4_network_cidr: 10.100.128.0/24
        vpn_connection_remote_ipv4_network_cidr: 10.10.80.0/24
        vpn_connection_static_routes_destinations:
          - 10.100.128.0/24
        vpn_connection_tunnel1_startup_action: add
        vpn_connection_tunnel2_startup_action: add
        transit_gateway_enabled: false
        vpn_connection_tunnel1_cloudwatch_log_enabled: false
        vpn_connection_tunnel2_cloudwatch_log_enabled: false
        preshared_key_enabled: true
        ssm_enabled: true
        ssm_path_prefix: "/site-to-site-vpn"

Amazon side Autonomous System Number (ASN)

The variable vpn_gateway_amazon_side_asn (Amazon side Autonomous System Number) is not strictly required when creating an AWS VPN Gateway. If you do not specify Amazon side ASN during the creation of the VPN Gateway, AWS will automatically assign a default ASN (which is 7224 for the Amazon side of the VPN).

However, specifying Amazon side ASN can be important if you need to integrate the VPN with an on-premises network that uses Border Gateway Protocol (BGP) and you want to avoid ASN conflicts or require a specific ASN for routing policies.

If your use case involves BGP peering, and you need a specific ASN for the Amazon side, then you should explicitly set the vpn_gateway_amazon_side_asn. Otherwise, it can be omitted (set to null), and AWS will handle it automatically.

Provisioning

Provision the site-to-site-vpn component by executing the following commands:

atmos terraform plan site-to-site-vpn -s <stack>
atmos terraform apply site-to-site-vpn -s <stack>

References

• https://aws.amazon.com/vpn/site-to-site-vpn
• https://docs.aws.amazon.com/vpn/latest/s2svpn/VPC_VPN.html
• https://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_VpnTunnelOptionsSpecification.html

Variables

Required Variables

customer_gateway_bgp_asn (number) required

The Customer Gateway's Border Gateway Protocol (BGP) Autonomous System Number (ASN)

region (string) required

AWS Region

Optional Variables

customer_gateway_ip_address (string) optional

The IPv4 address for the Customer Gateway device's outside interface. Set to null to not create the Customer Gateway

Default value: null

existing_transit_gateway_id (string) optional

Existing Transit Gateway ID. If provided, the module will not create a Virtual Private Gateway but instead will use the transit_gateway. For setting up transit gateway we can use the cloudposse/transit-gateway/aws module and pass the output transit_gateway_id to this variable

Default value: ""

preshared_key_enabled (bool) optional

Flag to enable adding the preshared keys to the VPN connection

Default value: true

ssm_enabled (bool) optional

Flag to enable saving the tunnel1_preshared_key and tunnel2_preshared_key in the SSM Parameter Store

Default value: false

ssm_path_prefix (string) optional

SSM Key path prefix for the associated SSM parameters

Default value: ""

transit_gateway_enabled (bool) optional

Set to true to enable VPN connection to transit gateway and then pass in the existing_transit_gateway_id

Default value: false

transit_gateway_route_table_id (string) optional

The ID of the route table for the transit gateway that you want to associate + propagate the VPN connection's TGW attachment

Default value: null

transit_gateway_routes optional

A map of transit gateway routes to create on the given TGW route table (via transit_gateway_route_table_id) for the created VPN Attachment. Use the key in the map to describe the route

Type:

map(object({
blackhole              = optional(bool, false)
destination_cidr_block = string
}))

Default value: { }

vpc_component_name (string) optional

Atmos VPC component name

Default value: "vpc"

vpn_connection_local_ipv4_network_cidr (string) optional

The IPv4 CIDR on the Customer Gateway (on-premises) side of the VPN connection

Default value: "0.0.0.0/0"

vpn_connection_log_retention_in_days (number) optional

Specifies the number of days you want to retain log events

Default value: 30

vpn_connection_remote_ipv4_network_cidr (string) optional

The IPv4 CIDR on the AWS side of the VPN connection

Default value: "0.0.0.0/0"

vpn_connection_static_routes_destinations (list(string)) optional

List of CIDR blocks to be used as destination for static routes. Routes to destinations will be propagated to the VPC route tables

Default value: [ ]

vpn_connection_static_routes_only (bool) optional

If set to true, the VPN connection will use static routes exclusively. Static routes must be used for devices that don't support BGP

Default value: false

vpn_connection_tunnel1_cloudwatch_log_enabled (bool) optional

Enable or disable VPN tunnel logging feature for the tunnel

Default value: false

vpn_connection_tunnel1_cloudwatch_log_output_format (string) optional

Set log format for the tunnel. Default format is json. Possible values are json and text

Default value: "json"

vpn_connection_tunnel1_dpd_timeout_action (string) optional

The action to take after DPD timeout occurs for the first VPN tunnel. Specify restart to restart the IKE initiation. Specify clear to end the IKE session. Valid values are clear | none | restart

Default value: "clear"

vpn_connection_tunnel1_ike_versions (list(string)) optional

The IKE versions that are permitted for the first VPN tunnel. Valid values are ikev1 | ikev2

Default value: [ ]

vpn_connection_tunnel1_inside_cidr (string) optional

The CIDR block of the inside IP addresses for the first VPN tunnel

Default value: null

vpn_connection_tunnel1_phase1_dh_group_numbers (list(string)) optional

List of one or more Diffie-Hellman group numbers that are permitted for the first VPN tunnel for phase 1 IKE negotiations. Valid values are 2 | 5 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24

Default value: [ ]

vpn_connection_tunnel1_phase1_encryption_algorithms (list(string)) optional

List of one or more encryption algorithms that are permitted for the first VPN tunnel for phase 1 IKE negotiations. Valid values are AES128 | AES256 | AES128-GCM-16 | AES256-GCM-16

Default value: [ ]

vpn_connection_tunnel1_phase1_integrity_algorithms (list(string)) optional

One or more integrity algorithms that are permitted for the first VPN tunnel for phase 1 IKE negotiations. Valid values are SHA1 | SHA2-256 | SHA2-384 | SHA2-512

Default value: [ ]

vpn_connection_tunnel1_phase2_dh_group_numbers (list(string)) optional

List of one or more Diffie-Hellman group numbers that are permitted for the first VPN tunnel for phase 2 IKE negotiations. Valid values are 2 | 5 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24

Default value: [ ]

vpn_connection_tunnel1_phase2_encryption_algorithms (list(string)) optional

List of one or more encryption algorithms that are permitted for the first VPN tunnel for phase 2 IKE negotiations. Valid values are AES128 | AES256 | AES128-GCM-16 | AES256-GCM-16

Default value: [ ]

vpn_connection_tunnel1_phase2_integrity_algorithms (list(string)) optional

One or more integrity algorithms that are permitted for the first VPN tunnel for phase 2 IKE negotiations. Valid values are SHA1 | SHA2-256 | SHA2-384 | SHA2-512

Default value: [ ]

vpn_connection_tunnel1_preshared_key (string) optional

The preshared key of the first VPN tunnel. The preshared key must be between 8 and 64 characters in length and cannot start with zero. Allowed characters are alphanumeric characters, periods(.) and underscores(_)

Default value: null

vpn_connection_tunnel1_startup_action (string) optional

The action to take when the establishing the tunnel for the first VPN connection. By default, your customer gateway device must initiate the IKE negotiation and bring up the tunnel. Specify start for AWS to initiate the IKE negotiation. Valid values are add | start

Default value: "add"

vpn_connection_tunnel2_cloudwatch_log_enabled (bool) optional

Enable or disable VPN tunnel logging feature for the tunnel

Default value: false

vpn_connection_tunnel2_cloudwatch_log_output_format (string) optional

Set log format for the tunnel. Default format is json. Possible values are json and text

Default value: "json"

vpn_connection_tunnel2_dpd_timeout_action (string) optional

The action to take after DPD timeout occurs for the second VPN tunnel. Specify restart to restart the IKE initiation. Specify clear to end the IKE session. Valid values are clear | none | restart

Default value: "clear"

vpn_connection_tunnel2_ike_versions (list(string)) optional

The IKE versions that are permitted for the second VPN tunnel. Valid values are ikev1 | ikev2

Default value: [ ]

vpn_connection_tunnel2_inside_cidr (string) optional

The CIDR block of the inside IP addresses for the second VPN tunnel

Default value: null

vpn_connection_tunnel2_phase1_dh_group_numbers (list(string)) optional

List of one or more Diffie-Hellman group numbers that are permitted for the second VPN tunnel for phase 1 IKE negotiations. Valid values are 2 | 5 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24

Default value: [ ]

vpn_connection_tunnel2_phase1_encryption_algorithms (list(string)) optional

List of one or more encryption algorithms that are permitted for the second VPN tunnel for phase 1 IKE negotiations. Valid values are AES128 | AES256 | AES128-GCM-16 | AES256-GCM-16

Default value: [ ]

vpn_connection_tunnel2_phase1_integrity_algorithms (list(string)) optional

One or more integrity algorithms that are permitted for the second VPN tunnel for phase 1 IKE negotiations. Valid values are SHA1 | SHA2-256 | SHA2-384 | SHA2-512

Default value: [ ]

vpn_connection_tunnel2_phase2_dh_group_numbers (list(string)) optional

List of one or more Diffie-Hellman group numbers that are permitted for the second VPN tunnel for phase 2 IKE negotiations. Valid values are 2 | 5 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24

Default value: [ ]

vpn_connection_tunnel2_phase2_encryption_algorithms (list(string)) optional

List of one or more encryption algorithms that are permitted for the second VPN tunnel for phase 2 IKE negotiations. Valid values are AES128 | AES256 | AES128-GCM-16 | AES256-GCM-16

Default value: [ ]

vpn_connection_tunnel2_phase2_integrity_algorithms (list(string)) optional

One or more integrity algorithms that are permitted for the second VPN tunnel for phase 2 IKE negotiations. Valid values are SHA1 | SHA2-256 | SHA2-384 | SHA2-512

Default value: [ ]

vpn_connection_tunnel2_preshared_key (string) optional

The preshared key of the second VPN tunnel. The preshared key must be between 8 and 64 characters in length and cannot start with zero. Allowed characters are alphanumeric characters, periods(.) and underscores(_)

Default value: null

vpn_connection_tunnel2_startup_action (string) optional

The action to take when the establishing the tunnel for the second VPN connection. By default, your customer gateway device must initiate the IKE negotiation and bring up the tunnel. Specify start for AWS to initiate the IKE negotiation. Valid values are add | start

Default value: "add"

vpn_gateway_amazon_side_asn (number) optional

The Autonomous System Number (ASN) for the Amazon side of the VPN Gateway. If you don't specify an ASN, the Virtual Private Gateway is created with the default ASN

Default value: null

Context Variables

The following variables are defined in the context.tf file of this module and part of the terraform-null-label pattern.

additional_tag_map (map(string)) optional

Additional key-value pairs to add to each map in tags_as_list_of_maps. Not added to tags or id.
This is for some rare cases where resources want additional configuration of tags
and therefore take a list of maps with tag key, value, and additional configuration.

Required: No

Default value: { }

attributes (list(string)) optional

ID element. Additional attributes (e.g. workers or cluster) to add to id,
in the order they appear in the list. New attributes are appended to the
end of the list. The elements of the list are joined by the delimiter
and treated as a single ID element.

Required: No

Default value: [ ]

context (any) optional

Single object for setting entire context at once.
See description of individual variables for details.
Leave string and numeric variables as null to use default value.
Individual variable settings (non-null) override settings in context object,
except for attributes, tags, and additional_tag_map, which are merged.

Required: No

Default value:

{
  "additional_tag_map": {},
  "attributes": [],
  "delimiter": null,
  "descriptor_formats": {},
  "enabled": true,
  "environment": null,
  "id_length_limit": null,
  "label_key_case": null,
  "label_order": [],
  "label_value_case": null,
  "labels_as_tags": [
    "unset"
  ],
  "name": null,
  "namespace": null,
  "regex_replace_chars": null,
  "stage": null,
  "tags": {},
  "tenant": null
}

delimiter (string) optional

Delimiter to be used between ID elements.
Defaults to - (hyphen). Set to "" to use no delimiter at all.

Required: No

Default value: null

descriptor_formats (any) optional

Describe additional descriptors to be output in the descriptors output map.
Map of maps. Keys are names of descriptors. Values are maps of the form
\{<br/> format = string<br/> labels = list(string)<br/> \}
(Type is any so the map values can later be enhanced to provide additional options.)
format is a Terraform format string to be passed to the format() function.
labels is a list of labels, in order, to pass to format() function.
Label values will be normalized before being passed to format() so they will be
identical to how they appear in id.
Default is {} (descriptors output will be empty).

Required: No

Default value: { }

enabled (bool) optional

Set to false to prevent the module from creating any resources
Required: No

Default value: null

environment (string) optional

ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'
Required: No

Default value: null

id_length_limit (number) optional

Limit id to this many characters (minimum 6).
Set to 0 for unlimited length.
Set to null for keep the existing setting, which defaults to 0.
Does not affect id_full.

Required: No

Default value: null

label_key_case (string) optional

Controls the letter case of the tags keys (label names) for tags generated by this module.
Does not affect keys of tags passed in via the tags input.
Possible values: lower, title, upper.
Default value: title.

Required: No

Default value: null

label_order (list(string)) optional

The order in which the labels (ID elements) appear in the id.
Defaults to ["namespace", "environment", "stage", "name", "attributes"].
You can omit any of the 6 labels ("tenant" is the 6th), but at least one must be present.

Required: No

Default value: null

label_value_case (string) optional

Controls the letter case of ID elements (labels) as included in id,
set as tag values, and output by this module individually.
Does not affect values of tags passed in via the tags input.
Possible values: lower, title, upper and none (no transformation).
Set this to title and set delimiter to "" to yield Pascal Case IDs.
Default value: lower.

Required: No

Default value: null

labels_as_tags (set(string)) optional

Set of labels (ID elements) to include as tags in the tags output.
Default is to include all labels.
Tags with empty values will not be included in the tags output.
Set to [] to suppress all generated tags.
Notes:
The value of the name tag, if included, will be the id, not the name.
Unlike other null-label inputs, the initial setting of labels_as_tags cannot be
changed in later chained modules. Attempts to change it will be silently ignored.

Required: No

Default value:

[
  "default"
]

name (string) optional

ID element. Usually the component or solution name, e.g. 'app' or 'jenkins'.
This is the only ID element not also included as a tag.
The "name" tag is set to the full id string. There is no tag with the value of the name input.

Required: No

Default value: null

namespace (string) optional

ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique
Required: No

Default value: null

regex_replace_chars (string) optional

Terraform regular expression (regex) string.
Characters matching the regex will be removed from the ID elements.
If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits.

Required: No

Default value: null

stage (string) optional

ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'
Required: No

Default value: null

tags (map(string)) optional

Additional tags (e.g. {'BusinessUnit': 'XYZ'}).
Neither the tag keys nor the tag values will be modified by this module.

Required: No

Default value: { }

tenant (string) optional

ID element (Rarely used, not included by default). A customer identifier, indicating who this instance of a resource is for
Required: No

Default value: null

Outputs

customer_gateway_id

Customer Gateway ID

vpn_connection_customer_gateway_configuration

The configuration information for the VPN connection's Customer Gateway (in the native XML format)

vpn_connection_id

VPN Connection ID

vpn_connection_tunnel1_address

The public IP address of the first VPN tunnel

vpn_connection_tunnel1_cgw_inside_address

The RFC 6890 link-local address of the first VPN tunnel (Customer Gateway side)

vpn_connection_tunnel1_vgw_inside_address

The RFC 6890 link-local address of the first VPN tunnel (Virtual Private Gateway side)

vpn_connection_tunnel2_address

The public IP address of the second VPN tunnel

vpn_connection_tunnel2_cgw_inside_address

The RFC 6890 link-local address of the second VPN tunnel (Customer Gateway side)

vpn_connection_tunnel2_vgw_inside_address

The RFC 6890 link-local address of the second VPN tunnel (Virtual Private Gateway side)

vpn_gateway_id

Virtual Private Gateway ID

Dependencies

Requirements

• terraform, version: >= 1.3.0
• aws, version: >= 4.0
• random, version: >= 2.2

Providers

• aws, version: >= 4.0
• random, version: >= 2.2

Modules

Name	Version	Source	Description
iam_roles	latest	../account-map/modules/iam-roles	n/a
this	0.25.0	cloudposse/label/null	n/a
vpc	1.5.0	cloudposse/stack-config/yaml//modules/remote-state	n/a
vpn_connection	1.3.1	cloudposse/vpn-connection/aws	n/a

Resources

The following resources are used by this module:

• aws_ssm_parameter.tunnel1_preshared_key (resource)
• aws_ssm_parameter.tunnel2_preshared_key (resource)
• random_password.tunnel1_preshared_key (resource)
• random_password.tunnel2_preshared_key (resource)

Data Sources

The following data sources are used by this module:

• cloudposse/terraform-aws-components - Cloud Posse's upstream component