Identity and access management in Amazon Transit Gateway
Amazon uses security credentials to identify you and to grant you access to your Amazon resources. You can use features of Amazon Identity and Access Management (IAM) to allow other users, services, and applications to use your Amazon resources fully or in a limited way, without sharing your security credentials.
By default, IAM users don't have permission to create, view, or modify Amazon resources. To allow a user to access resources such as a transit gateway, and to perform tasks, you must create an IAM policy that grants the user permission to use the specific resources and API actions they'll need, then attach the policy to the group to which that user belongs. When you attach a policy to a user or group of users, it allows or denies the users permission to perform the specified tasks on the specified resources.
To work with a transit gateway, one of the following Amazon managed policies might meet your needs:
Example policies to manage transit gateways
The following are example IAM policies for working with transit gateways.
Create a transit gateway with required tags
The following example enables users to create transit gateway. The
aws:RequestTag condition key requires users to tag the transit
gateway with the tag stack=prod. The aws:TagKeys condition
key uses the ForAllValues modifier to indicate that only the key
stack is allowed in the request (no other tags can be specified).
If users don't pass this specific tag when they create the transit gateway, or if
they don't specify tags at all, the request fails.
The second statement uses the ec2:CreateAction condition key to allow
users to create tags only in the context of CreateTransitGateway.
Working with transit gateway route tables
The following example enables users to create and delete transit gateway route
tables for a specific transit gateway only (tgw-11223344556677889).
Users can also create and replace routes in any transit gateway route table, but
only for attachments that have the tag network=new-york-office.
Permissions for 1:1 NAT
Only the transit gateway owner can view or modify the NAT configuration of an attachment. This applies to every attachment on the transit gateway, including attachments owned by other accounts through Amazon RAM sharing. Attachment owners can't view or change NAT configuration, and the transit gateway owner can't delegate this to them. The following table shows the result for each caller.
| Caller | GetTransitGatewayAttachmentNatConfiguration /
ModifyTransitGatewayAttachmentNatConfiguration |
NatGatewaySupport in
DescribeTransitGatewayAttachments |
|---|---|---|
| transit gateway owner | Allowed | Included |
| Attachment owner (different account) | UnauthorizedOperation |
Not included |
| Any other account | InvalidTransitGatewayAttachmentID.NotFound |
Attachment not returned |
The following table lists the IAM actions for 1:1 NAT.
| Action | Purpose |
|---|---|
ec2:ModifyTransitGatewayAttachmentNatConfiguration |
Enable or disable NAT, and set NAT rules and route options. |
ec2:GetTransitGatewayAttachmentNatConfiguration |
View NAT configuration. Policies that grant ec2:Describe*
don't include this action. |
Both actions support resource-level permissions on the transit gateway attachment. To restrict which attachments a principal can manage, specify the attachment ARN or use tag-based conditions.
The following example allows NAT management only on attachments tagged
environment=prod.
{ "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": [ "ec2:ModifyTransitGatewayAttachmentNatConfiguration", "ec2:GetTransitGatewayAttachmentNatConfiguration" ], "Resource": "arn:aws:ec2:*:*:transit-gateway-attachment/*", "Condition": { "StringEquals": { "ec2:ResourceTag/environment": "prod" } } } ] }