Configure instance metadata options for new instances - Amazon Elastic Compute Cloud
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Configure instance metadata options for new instances

You can configure the following instance metadata options for new instances.

Note

The settings for these options are configured at the account level, either directly in the account or by using a declarative policy. They must be configured in each AWS Region where you want to configure instance metadata options. Using a declarative policy allows you to apply the settings across multiple Regions simultaneously, as well as across multiple accounts simultaneously. When a declarative policy is in use, you can't modify the settings directly within an account. This topic describes how to configure the settings directly within an account. For information about using declarative policies, see Declarative policies in the AWS Organizations User Guide.

Require the use of IMDSv2

You can use the following methods to require the use of IMDSv2 on your new instances.

Set IMDSv2 as the default for the account

You can set the default version for the instance metadata service (IMDS) at the account level for each AWS Region. This means that when you launch a new instance, the instance metadata version is automatically set to the account-level default. However, you can manually override the value at launch or after launch. For more information about how the account-level settings and manual overrides affect an instance, see Order of precedence for instance metadata options.

Note

Setting the account-level default does not reset existing instances. For example, if you set the account-level default to IMDSv2, any existing instances that are set to IMDSv1 are not affected. If you want to change the value on existing instances, you must manually change the value on the instances themselves.

You can set the account default for the instance metadata version to IMDSv2 so that all new instances in the account launch with IMDSv2 required, and IMDSv1 will be disabled. With this account default, when you launch an instance, the following are the default values for the instance:

  • Console: Metadata version is set to V2 only (token required) and Metadata response hop limit is set to 2.

  • AWS CLI: HttpTokens is set to required and HttpPutResponseHopLimit is set to 2.

Note

Before setting the account default to IMDSv2, ensure that your instances do not depend on IMDSv1. For more information, see Recommended path to requiring IMDSv2.

Console
To set IMDSv2 as the default for the account for the specified Region

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

  2. To change the AWS Region, use the Region selector in the upper-right corner of the page.

  3. In the navigation pane, choose EC2 Dashboard.

  4. Under Account attributes, choose Data protection and security.

  5. Next to IMDS defaults, choose Manage.

  6. On the Manage IMDS defaults page, do the following:

    1. For Instance metadata service, choose Enabled.

    2. For Metadata version, choose V2 only (token required).

    3. For Metadata response hop limit, specify 2 if your instances will host containers. Otherwise, select No preference. When no preference is specified, at launch, the value defaults to 2 if the AMI has the setting ImdsSupport: v2.0; otherwise it defaults to 1.

    4. Choose Update.

AWS CLI
To set IMDSv2 as the default for the account for the specified Region

Use the modify-instance-metadata-defaults command and specify the Region in which to modify the IMDS account level settings. Include --http-tokens set to required and --http-put-response-hop-limit set to 2 if your instances will host containers. Otherwise, specify -1 to indicate no preference. When -1 (no preference) is specified, at launch, the value defaults to 2 if the AMI has the setting ImdsSupport: v2.0; otherwise it defaults to 1.

aws ec2 modify-instance-metadata-defaults \
    --region us-east-1 \
    --http-tokens required \
    --http-put-response-hop-limit 2

The following is example output.

{
    "Return": true
}
To view the default account settings for the instance metadata options for the specified Region

Use the get-instance-metadata-defaults command and specify the Region.

aws ec2 get-instance-metadata-defaults --region us-east-1

The following is example output.

{
    "AccountLevel": {
        "HttpTokens": "required",
        "HttpPutResponseHopLimit": 2
    },
    "ManagedBy": "account"
}

The ManagedBy field indicates the entity that configured the settings. In this example, account indicates that the settings were configured directly in the account. A value of declarative-policy would mean the settings were configured by a declarative policy. For more information, see Declarative policies in the AWS Organizations User Guide.

To set IMDSv2 as the default for the account for all Regions

Use the modify-instance-metadata-defaults command to modify the IMDS account level settings for all Regions. Include --http-tokens set to required and --http-put-response-hop-limit set to 2 if your instances will host containers. Otherwise, specify -1 to indicate no preference. When -1 (no preference) is specified, at launch, the value defaults to 2 if the AMI has the setting ImdsSupport: v2.0; otherwise it defaults to 1.

echo -e "Region          \t Modified" ; \
echo -e "--------------  \t ---------" ; \
for region in $(
    aws ec2 describe-regions \
        --region us-east-1 \
        --query "Regions[*].[RegionName]" \
        --output text
    ); 
    do (output=$(
        aws ec2 modify-instance-metadata-defaults \
            --region $region \
            --http-tokens required \
            --http-put-response-hop-limit 2 \
            --output text)
        echo -e "$region        \t $output"
    );
done

The following is example output.

Region                   Modified
--------------           ---------
ap-south-1               True
eu-north-1               True
eu-west-3                True
...
To view the default account settings for the instance metadata options for all Regions

Use the get-instance-metadata-defaults command.

echo -e "Region   \t Level          Hops    HttpTokens" ; \
echo -e "-------------- \t ------------   ----    ----------" ; \
for region in $(
    aws ec2 describe-regions \
        --region us-east-1 \
        --query "Regions[*].[RegionName]" \
        --output text
    ); 
    do (output=$(
        aws ec2 get-instance-metadata-defaults \
            --region $region \
            --output text)
        echo -e "$region \t $output" 
    );
done

The following is example output.

Region           Level          Hops    HttpTokens
--------------   ------------   ----    ----------
ap-south-1       ACCOUNTLEVEL   2       required
eu-north-1       ACCOUNTLEVEL   2       required
eu-west-3        ACCOUNTLEVEL   2       required
...
PowerShell
To set IMDSv2 as the default for the account for the specified Region

Use the Edit-EC2InstanceMetadataDefault command and specify the Region in which to modify the IMDS account level settings. Include -HttpToken set to required and -HttpPutResponseHopLimit set to 2 if your instances will host containers. Otherwise, specify -1 to indicate no preference. When -1 (no preference) is specified, at launch, the value defaults to 2 if the AMI has the setting ImdsSupport: v2.0; otherwise it defaults to 1.

Edit-EC2InstanceMetadataDefault `
    -Region us-east-1 `
    -HttpToken required `
    -HttpPutResponseHopLimit 2

The following is example output.

True
To view the default account settings for the instance metadata options for the specified Region

Use the Get-EC2InstanceMetadataDefault command and specify the Region.

Get-EC2InstanceMetadataDefault -Region us-east-1 | Format-List

The following is example output.

HttpEndpoint            : 
HttpPutResponseHopLimit : 2
HttpTokens              : required
InstanceMetadataTags    :
To set IMDSv2 as the default for the account for all Regions

Use the Edit-EC2InstanceMetadataDefault Cmdlet to modify the IMDS account level settings for all Regions. Include -HttpToken set to required and -HttpPutResponseHopLimit set to 2 if your instances will host containers. Otherwise, specify -1 to indicate no preference. When -1 (no preference) is specified, at launch, the value defaults to 2 if the AMI has the setting ImdsSupport: v2.0; otherwise it defaults to 1.

(Get-EC2Region).RegionName | `
    ForEach-Object {
    [PSCustomObject]@{
        Region   = $_
        Modified = (Edit-EC2InstanceMetadataDefault `
                -Region $_ `
                -HttpToken required `
                -HttpPutResponseHopLimit 2)
    } 
} | `
Format-Table Region, Modified -AutoSize

Expected output

Region         Modified
------         --------
ap-south-1         True
eu-north-1         True
eu-west-3          True
...
To view the default account settings for the instance metadata options for all Regions

Use the Get-EC2InstanceMetadataDefault Cmdlet.

(Get-EC2Region).RegionName | `
    ForEach-Object {
    [PSCustomObject]@{
        Region = $_
        HttpPutResponseHopLimit = (Get-EC2InstanceMetadataDefault -Region $_).HttpPutResponseHopLimit
        HttpTokens              = (Get-EC2InstanceMetadataDefault -Region $_).HttpTokens
    }
} | `
Format-Table -AutoSize

Example output

Region         HttpPutResponseHopLimit HttpTokens
------         ----------------------- ----------
ap-south-1                           2 required
eu-north-1                           2 required
eu-west-3                            2 required                    
...

Configure the instance at launch

When you launch an instance, you can configure the instance to require the use of IMDSv2 by configuring the following fields:

  • Amazon EC2 console: Set Metadata version to V2 only (token required).

  • AWS CLI: Set HttpTokens to required.

When you specify that IMDSv2 is required, you must also enable the Instance Metadata Service (IMDS) endpoint by setting Metadata accessible to Enabled (console) or HttpEndpoint to enabled (AWS CLI).

In a container environment, when IMDSv2 is required, we recommend setting the hop limit to 2. For more information, see Instance metadata access considerations.

Console
To require the use of IMDSv2 on a new instance

  • When launching a new instance in the Amazon EC2 console, expand Advanced details, and do the following:

    • For Metadata accessible, choose Enabled.

    • For Metadata version, choose V2 only (token required).

    • (Container environment) For Metadata response hop limit, choose 2.

    For more information, see Advanced details.

AWS CLI
To require the use of IMDSv2 on a new instance

The following run-instances example launches a c6i.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 requires the instance to use IMDSv2 when requesting instance metadata.

In a container environment, when IMDSv2 is required, we recommend setting the hop limit to 2 with HttpPutResponseHopLimit=2.

aws ec2 run-instances \
    --image-id ami-0abcdef1234567890 \
    --instance-type c6i.large \
	...
    --metadata-options "HttpEndpoint=enabled,HttpTokens=required,HttpPutResponseHopLimit=2"
PowerShell
To require the use of IMDSv2 on a new instance

The following New-EC2Instance Cmdlet example launches a c6i.large instance with MetadataOptions_HttpEndpoint set to enabled and the MetadataOptions_HttpTokens parameter to 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 requires the instance to use IMDSv2 when requesting instance metadata.

New-EC2Instance `
    -ImageId ami-0abcdef1234567890 `
    -InstanceType c6i.large `
    -MetadataOptions_HttpEndpoint enabled `
    -MetadataOptions_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.

Configure the AMI

When you register a new AMI or modify an existing AMI, you can set the imds-support parameter to v2.0. Instances launched from this AMI will have Metadata version set to V2 only (token required) (console) or HttpTokens set to required (AWS CLI). With these settings, the instance requires that IMDSv2 is used when requesting instance metadata.

Note that when you set imds-support to v2.0, instances launched from this AMI will also have Metadata response hop limit (console) or http-put-response-hop-limit (AWS CLI) set to 2.

Important

Do not use this parameter unless your AMI software supports IMDSv2. After you set the value to v2.0, you can't undo it. The only way to "reset" your AMI is to create a new AMI from the underlying snapshot.

To configure a new AMI for IMDSv2

Use one of the following methods to configure a new AMI for IMDSv2.

AWS CLI

The following register-image example registers an AMI using the specified snapshot of an EBS root volume as device /dev/xvda. Specify v2.0 for the imds-support parameter so that instances launched from this AMI will require that IMDSv2 is used when requesting instance metadata.

aws ec2 register-image \
    --name my-image \
    --root-device-name /dev/xvda \
    --block-device-mappings DeviceName=/dev/xvda,Ebs={SnapshotId=snap-0123456789example} \
    --architecture x86_64 \
    --imds-support v2.0
PowerShell

The following Register-EC2Image Cmdlet example registers an AMI using the specified snapshot of an EBS root volume as device /dev/xvda. Specify v2.0 for the ImdsSupport parameter so that instances launched from this AMI will require that IMDSv2 is used when requesting instance metadata.

Register-EC2Image `
    -Name 'my-image' `
    -RootDeviceName /dev/xvda `
    -BlockDeviceMapping  ( 
    New-Object `
        -TypeName Amazon.EC2.Model.BlockDeviceMapping `
        -Property @{ 
        DeviceName = '/dev/xvda'; 
        EBS        = (New-Object -TypeName Amazon.EC2.Model.EbsBlockDevice -Property @{ 
                SnapshotId = 'snap-0123456789example'
                VolumeType = 'gp3' 
                } )      
        }  ) `
    -Architecture X86_64 `
    -ImdsSupport v2.0
To configure an existing AMI for IMDSv2

Use one of the following methods to configure an existing AMI for IMDSv2.

AWS CLI

The following modify-image-attribute example modifies an existing AMI for IMDSv2 only. Specify v2.0 for the imds-support parameter so that instances launched from this AMI will require that IMDSv2 is used when requesting instance metadata.

aws ec2 modify-image-attribute \
    --image-id ami-0abcdef1234567890 \
    --imds-support v2.0
PowerShell

The following Edit-EC2ImageAttribute Cmdlet example modifies an existing AMI for IMDSv2 only. Specify v2.0 for the imds-support parameter so that instances launched from this AMI will require that IMDSv2 is used when requesting instance metadata.

Edit-EC2ImageAttribute `
    -ImageId ami-0abcdef1234567890 `
    -ImdsSupport 'v2.0'

Use an IAM policy

You can create an IAM policy that prevents users from launching new instances unless they require IMDSv2 on the new instance.

To enforce the use of IMDSv2 on all new instances by using an IAM policy

To ensure that 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.

Enable the IMDS IPv4 and IPv6 endpoints

The IMDS has two endpoints on an instance: IPv4 (169.254.169.254) and IPv6 ([fd00:ec2::254]). When you enable the IMDS, the IPv4 endpoint is automatically enabled. The IPv6 endpoint remains disabled even if you launch an instance into an IPv6-only subnet. To enable the IPv6 endpoint, you need to do so explicitly. When you enable the IPv6 endpoint, the IPv4 endpoint remains enabled.

You can enable the IPv6 endpoint at instance launch or after.

Requirements for enabling the IPv6 endpoint

Use any of the following methods to launch an instance with the IMDS IPv6 endpoint enabled.

Console
To enable the IMDS IPv6 endpoint at instance launch

  • Launch the instance in the Amazon EC2 console with the following specified under Advanced details:

    • For Metadata IPv6 endpoint, choose Enabled.

For more information, see Advanced details.

AWS CLI
To enable the IMDS IPv6 endpoint at instance launch

The following run-instances example launches a c6i.large instance with the IPv6 endpoint enabled for the IMDS. To enable the IPv6 endpoint, for the --metadata-options parameter, specify HttpProtocolIpv6=enabled. When you specify a value for HttpProtocolIpv6, you must also set HttpEndpoint to enabled.

aws ec2 run-instances \
    --image-id ami-0abcdef1234567890 \
    --instance-type c6i.large \
    ...
    --metadata-options "HttpEndpoint=enabled,HttpProtocolIpv6=enabled"
PowerShell
To enable the IMDS IPv6 endpoint at instance launch

The following New-EC2Instance Cmdlet example launches a c6i.large instance with the IPv6 endpoint enabled for the IMDS. To enable the IPv6 endpoint, specify MetadataOptions_HttpProtocolIpv6 as enabled. When you specify a value for MetadataOptions_HttpProtocolIpv6, you must also set MetadataOptions_HttpEndpoint to enabled.

New-EC2Instance `
    -ImageId ami-0abcdef1234567890 `
    -InstanceType c6i.large `
    -MetadataOptions_HttpEndpoint enabled `
    -MetadataOptions_HttpProtocolIpv6 enabled

Turn off access to instance metadata

You can turn off access to the instance metadata by disabling the IMDS when you launch an instance. You can turn on access later by re-enabling the IMDS. For more information, see Turn on access to instance metadata.

Important

You can choose to disable the IMDS at launch or after launch. If you disable the IMDS at launch, the following might not work:

  • You might not have SSH access to your instance. The public-keys/0/openssh-key, which is your instance's public SSH key, will not be accessible because the key is normally provided and accessed from EC2 instance metadata.

  • EC2 user data will not be available and will not run at instance start. EC2 user data is hosted on the IMDS. If you disable the IMDS, you effectively turn off access to user data.

To access this functionality, you can re-enable the IMDS after launch.

Console
To turn off access to instance metadata at launch

  • Launch the instance in the Amazon EC2 console with the following specified under Advanced details:

    • For Metadata accessible, choose Disabled.

For more information, see Advanced details.

AWS CLI
To turn off access to instance metadata at launch at launch

Launch the instance with --metadata-options set to HttpEndpoint=disabled.

aws ec2 run-instances \
    --image-id ami-0abcdef1234567890 \
    --instance-type c6i.large \
    ... 
    --metadata-options "HttpEndpoint=disabled"
PowerShell
To turn off access to instance metadata at launch at launch

The following New-EC2Instance Cmdlet example launches an instance with MetadataOptions_HttpEndpoint set to disabled.

New-EC2Instance `
    -ImageId ami-0abcdef1234567890 `
    -InstanceType c6i.large `
    -MetadataOptions_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.

Allow access to tags in instance metadata

By default, instance tags are not accessible in the instance metadata. For each instance, you must explicitly allow access. If access is allowed, instance tag keys must comply with specific character restrictions, otherwise the instance launch will fail. For more information, see Enable access to tags in instance metadata.