Configure the instance metadata options

Instance metadata options allow you to configure new or existing instances to do the following:

• Require the use of IMDSv2 when requesting instance metadata

• Specify the PUT response hop limit

• Turn off access to instance metadata

You can also use IAM condition keys in an IAM policy or SCP to do the following:

• Allow an instance to launch only if it's configured to require the use of IMDSv2

• Restrict the number of allowed hops

• Turn off access to instance metadata

Note

You should proceed cautiously and conduct careful testing before making any changes. Take note of the following:

• If you enforce the use of IMDSv2, applications or agents that use IMDSv1 for instance metadata access will break.

• If you turn off all access to instance metadata, applications or agents that rely on instance metadata access to function will break.

• For IMDSv2, you must use /latest/api/ token when retrieving the token.

Configure instance metadata options for new instances

You can require the use of IMDSv2 on an instance when you launch it. You can also create an IAM policy that prevents users from launching new instances unless they require IMDSv2 on the new instance.

Console

To require the use of IMDSv2 on a new instance

• When launching a new instance in the Amazon EC2 console, select the following options on the Configure Instance Details page:

  • Under Advanced Details, for Metadata accessible, select Enabled.

  • For Metadata version, select V2 (token required).

For more information, see Step 3: Configure Instance Details.

AWS CLI

To require the use of IMDSv2 on a new instance subnet

The following run-instances example launches a c3.large instance with --metadata-options set to HttpTokens=required. When you specify a value for HttpTokens, you must also set HttpEndpoint to enabled. Because the secure token header is set to required for metadata retrieval requests, this opts in the instance to require using IMDSv2 when requesting instance metadata.

aws ec2 run-instances 
    --image-id ami-0abcdef1234567890 
    --instance-type c3.large 
	...
    --metadata-options "HttpEndpoint=enabled,HttpTokens=required"

AWS CloudFormation

To specify the metadata options for an instance using AWS CloudFormation, see the AWS::EC2::LaunchTemplate MetadataOptions property in the AWS CloudFormation User Guide.

To enforce the use of IMDSv2 on all new instances

To ensure that IAM users can only launch instances that require the use of IMDSv2 when requesting instance metadata, you can specify that the condition to require IMDSv2 must be met before an instance can be launched. For the example IAM policy, see Work with instance metadata.

Configure IPv4 and IPv6 endpoints

By default, the IPv4 endpoint is enabled and the IPv6 endpoint is disabled. This is true even if you are launching an instance into an IPv6-only subnet. You can choose to enable or disable these endpoints at instance launch. The IPv6 endpoint for IMDS is only accessible on Instances built on the Nitro System. For more information on the metadata options, see run-instances in the AWS CLI command reference. The following example shows you how to enable both IPv4 and IPv6 endpoints for IMDS:

aws ec2 run-instances
    --image-id ami-0abcdef1234567890
    --instance-type t3.large
    ...
    --metadata-options "HttpEndpoint=enabled, HttpProtocolIpv4=enabled, HttpProtocolIpv6=enabled"

Console

To turn off access to instance metadata

• To ensure that access to your instance metadata is turned off, regardless of which version of the instance metadata service you are using, launch the instance in the Amazon EC2 console with the following option selected on the Configure Instance Details page:

  • Under Advanced Details, for Metadata accessible, select Disabled.

For more information, see Step 3: Configure Instance Details.

AWS CLI

To turn off access to instance metadata

To ensure that access to your instance metadata is turned off, regardless of which version of the instance metadata service you are using, launch the instance with --metadata-options set to HttpEndpoint=disabled. You can turn access on later by using the modify-instance-metadata-options command.

aws ec2 run-instances 
    --image-id ami-0abcdef1234567890 
    --instance-type c3.large 
    ... 
    --metadata-options "HttpEndpoint=disabled"

AWS CloudFormation

To specify the metadata options for an instance using AWS CloudFormation, see the AWS::EC2::LaunchTemplate MetadataOptions property in the AWS CloudFormation User Guide.

Modify instance metadata options for existing instances

You can require the use IMDSv2 on an existing instance. You can also change the PUT response hop limit and turn off access to instance metadata on an existing instance. You can also create an IAM policy that prevents users from modifying the instance metadata options on an existing instance.

Currently only the AWS SDK or AWS CLI support modifying the instance metadata options on existing instances. You can't use the Amazon EC2 console for modifying instance metadata options.

To require the use of IMDSv2

You can opt in to require that IMDSv2 is used when requesting instance metadata. Use the modify-instance-metadata-options CLI command and set the http-tokens parameter to required. When you specify a value for http-tokens, you must also set http-endpoint to enabled.

aws ec2 modify-instance-metadata-options \
    --instance-id i-1234567898abcdef0 \
    --http-tokens required \
    --http-endpoint enabled

To change the PUT response hop limit

For existing instances, you can change the settings of the PUT response hop limit. Use the modify-instance-metadata-options CLI command and set the http-put-response-hop-limit parameter to the required number of hops. In the following example, the hop limit is set to 3. Note that when specifying a value for http-put-response-hop-limit, you must also set http-endpoint to enabled.

aws ec2 modify-instance-metadata-options \
    --instance-id i-1234567898abcdef0 \
    --http-put-response-hop-limit 3 \
    --http-endpoint enabled

To restore the use of IMDSv1 on an instance using IMDSv2

You can use the modify-instance-metadata-options CLI command with http-tokens set to optional to restore the use of IMDSv1 when requesting instance metadata.

aws ec2 modify-instance-metadata-options \
    --instance-id i-1234567898abcdef0 \
    --http-tokens optional \
    --http-endpoint enabled

To turn on the IPv6 endpoint for your instance

By default, the IPv4 endpoint is enabled and the IPv6 endpoint is disabled. This is true even if you have launched an instance into an IPv6-only subnet. The IPv6 endpoint for IMDS is only accessible on Instances built on the Nitro System. For more information about the metadata options, see modify-instance-metadata-options in the AWS CLI command reference. The following example shows you how to turn on the IPv6 endpoint for the instance metadata service.

aws ec2 modify-instance-metadata-options \
	--instance-id i-1234567898abcdef0 \
	--http-protocol-ipv6 enabled \
	--http-endpoint enabled

To turn off access to instance metadata

You can turn off access to your instance metadata by disabling the HTTP endpoint of the instance metadata service, regardless of which version of the instance metadata service you are using. You can reverse this change at any time by enabling the HTTP endpoint. Use the modify-instance-metadata-options CLI command and set the http-endpoint parameter to disabled.

aws ec2 modify-instance-metadata-options \
    --instance-id i-1234567898abcdef0 \
    --http-endpoint disabled

To control the use of modify-instance-metadata-options

To control which IAM users can modify the instance metadata options, specify a policy that prevents all users other than users with a specified role to use the ModifyInstanceMetadataOptions API. For the example IAM policy, see Work with instance metadata.