Linux Windows
This document describes how to prevent users from accessing virtual machine (VM) instances by removing and blocking SSH keys from VMs.
Before you beginSelect the tab for how you plan to use the samples on this page:
ConsoleWhen you use the Google Cloud console to access Google Cloud services and APIs, you don't need to set up authentication.
gcloudInstall the Google Cloud CLI. After installation, initialize the Google Cloud CLI by running the following command:
gcloud init
If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.
Note: If you installed the gcloud CLI previously, make sure you have the latest version by runninggcloud components update
.To use the REST API samples on this page in a local development environment, you use the credentials you provide to the gcloud CLI.
Install the Google Cloud CLI. After installation, initialize the Google Cloud CLI by running the following command:
gcloud init
If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.
For more information, see Authenticate for using REST in the Google Cloud authentication documentation.
You can remove SSH keys from
VMs that use OS Loginand
VMs that use metadata-based SSH keys.
Remove SSH keys from VMs that use OS LoginVMs that use OS Login accept SSH keys that are associated with your Google account. You can remove a public SSH key from your user account using the Google Cloud CLI or the OS Login API. If you're an administrator for your organization, you can remove SSH keys from user accounts using the Directory API. Compute Engine automatically removes expired keys from your Google Account.
gcloudTo remove a public SSH key from your account, do the following:
If you don't know which key you want to remove, run the gcloud compute os-login describe-profile
command to view all keys associated with your account:
gcloud compute os-login describe-profile
Copy the fingerprint
value of the key you want to delete.
Remove the key from your account using the gcloud compute os-login ssh-keys remove
command:
gcloud compute os-login ssh-keys remove --key=KEY
Replace KEY
with the public SSH key you want to remove, or the OS Login fingerprint for the key you want to remove.
To remove a public SSH key from your account, do the following:
If you don't know which key you want to remove, use the users.getLoginProfile
method to view all keys associated with your account:
GET https://oslogin.googleapis.com/v1/users/ACCOUNT_EMAIL/loginProfile
Replace ACCOUNT_EMAIL
with the email address associated with your account.
Copy the fingerprint
value of the key you want to delete.
Remove the key from your account using the users.sshPublicKeys.delete
method:
DELETE https://oslogin.googleapis.com/v1/users/ACCOUNT_EMAIL/sshPublicKeys/FINGERPRINT
Replace the following:
ACCOUNT_EMAIL
: the email address associated with your accountFINGERPRINT
: the SHA-256 fingerprint of the key to removeYou can remove a public SSH key from project or instance metadata using the Google Cloud console, the gcloud CLI, or the Compute Engine API.
After you remove the last key from metadata for a particular user, or the last key in metadata for a particular user expires, Compute Engine deletes the user's ~/.ssh/authorized_keys
file on the VM.
Caution: If you manage SSH keys in metadata, you might disrupt the ability of your project members to connect to VMs. Additionally, you risk granting users, including users outside of your project, unintended access to VMs. For more information, see
risks of manual key management.
Remove a public key from project metadataRemove a public SSH key from project metadata to remove access to all VMs in a project.
When you remove a key from metadata using the gcloud CLI and the Compute Engine API, you must retrieve the list of existing keys, edit the list of keys to remove the unwanted keys, and overwrite the old keys with the list of keys you want to keep, as explained in the following section.
Permissions required for this taskTo perform this task, you must have the following permissions:
compute.projects.setCommonInstanceMetadata
To remove a public SSH key from project metadata using the Google Cloud console, do the following:
In the Google Cloud console, go to the Metadata page.
Click the SSH keys tab.
Click edit Edit at the top of the page.
Navigate to the SSH key that you want to remove and click the delete delete button next to the SSH key.
Repeat this step for each SSH key that you want to remove.
Click Save.
To remove a public SSH key from project metadata using the gcloud CLI, do the following:
Run gcloud compute project-info describe
command to get the metadata for the project:
gcloud compute project-info describe
The output is similar to the following:
...
metadata:
...
- key: ssh-keys
value: |-
cloudysanfrancisco:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDAu5kKQCPF
baklavainthebalkans:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDQDx3FNVC8 google-ssh {"userName":"baklavainthebalkans","expireOn":"2021-06-14T16:59:03+0000"}
...
Copy the ssh-keys
metadata value.
Create and open a new text file on your workstation.
In the file, paste the list of SSH keys that you just copied, then delete any keys you want to remove from project metadata.
Save and close the file.
Run the gcloud compute project-info add-metadata
command to set the project-wide ssh-keys
value:
gcloud compute project-info add-metadata --metadata-from-file=ssh-keys=KEY_FILE
Replace KEY_FILE
with one of the following:
To remove a public SSH key from project metadata using the Compute Engine API, do the following:
Use the projects.get
method to get the fingerprint
and ssh-keys
values from metadata.
GET https://compute.googleapis.com/compute/v1/projects/PROJECT_ID
Replace PROJECT_ID
with your project ID.
The response is similar to the following:
... "fingerprint": "utgYE_XWtE8=", "items": [ { "key": "ssh-keys", "value": "cloudysanfrancisco:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDAu5kKQCPF\nbaklavainthebalkans:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDQDx3FNVC8 google-ssh {"userName":"baklavainthebalkans","expireOn":"2021-06-14T16:59:03+0000"}" } ] ...
Copy the list of SSH key values and delete the keys you want to remove.
Use the projects.setCommonInstanceMetadata
to remove the SSH keys.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/setCommonInstanceMetadata { "items": [ { "key": "ssh-keys", "value": "EXISTING_SSH_KEYS" } ] "fingerprint": "FINGERPRINT" }
Replace the following:
PROJECT_ID
: your project IDEXISTING_SSH_KEYS
: the list of the SSH keys you want to keepFINGERPRINT
: the value of the fingerprint
from the response of the projects.get
requestRemove a public SSH key from instance metadata to remove access to a single VM.
When you remove a key from metadata using the gcloud CLI and the Compute Engine API, you must retrieve the list of existing keys, edit the list of keys to remove the unwanted keys, and overwrite the old keys with the list of keys you want to keep, as explained in the following section.
Permissions required for this taskTo perform this task, you must have the following permissions:
compute.instances.setMetadata
To remove a public SSH key from instance metadata using the Google Cloud console, do the following:
In the Google Cloud console, go to the VM instances page.
Click the name of the VM that you want to remove a key for.
Click Edit.
In SSH Keys section, click Show and edit. The section expands to show all of the instance-level public SSH keys.
Click the delete delete button next to the SSH key that you want to remove.
Repeat this step for each SSH key that you want to remove.
Click Save.
To remove a public SSH key from instance metadata using the gcloud CLI, do the following:
Run gcloud compute instances describe
command to get the metadata for the VM:
gcloud compute instances describe VM_NAME
Replace VM_NAME with the name of the VM for which you need to add or remove public SSH keys.
The output is similar to the following:
...
metadata:
...
- key: ssh-keys
value: |-
cloudysanfrancisco:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDAu5kKQCPF
baklavainthebalkans:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDQDx3FNVC8 google-ssh {"userName":"baklavainthebalkans","expireOn":"2021-06-14T16:59:03+0000"}
...
Copy the ssh-keys
metadata value.
Create and open a new text file on your local workstation.
In the file, paste the list of SSH keys that you just copied, then remove any keys you want to delete.
Save and close the file.
Run the gcloud compute project-info add-metadata
command to set the project-wide ssh-keys
value:
gcloud compute instances add-metadata VM_NAME --metadata-from-file ssh-keys=KEY_FILE
Replace the following:
VM_NAME
: the VM you want to remove the SSH key forKEY_FILE
: the path to the file that contains the list of all project SSH keysTo remove a public SSH key from instance metadata using the Compute Engine API, do the following:
Use the instances.get
method to get the fingerprint
and ssh-keys
values from metadata.
GET https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/VM_NAME
Replace the following:
PROJECT_ID
: your project IDZONE
: the zone of the VM you're adding an SSH key forVM_NAME
: the VM you're adding an SSH key forThe response is similar to the following:
... "fingerprint": "utgYE_XWtE8=", "items": [ { "key": "ssh-keys", "value": "cloudysanfrancisco:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDAu5kKQCPF\nbaklavainthebalkans:ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDQDx3FNVC8 google-ssh {"userName":"baklavainthebalkans","expireOn":"2021-06-14T16:59:03+0000"}" } ] ...
Copy the list of SSH key values and delete the keys you want to remove.
Use the instances.setMetadata
to remove the SSH keys.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/VM_NAME/setMetadata { "items": [ { "key": "ssh-keys", "value": "EXISTING_SSH_KEYS } ] "fingerprint": "FINGERPRINT" }
Replace the following:
PROJECT_ID
: your project IDEXISTING_SSH_KEYS
: the value of the ssh-keys
key from the response of the projects.get
requestFINGERPRINT
: the value of the fingerprint
from the response of the instances.get
requestYou can prevent VMs from accepting SSH keys that are stored in project metadata by blocking project SSH keys from VMs. You can block project SSH keys from VMs when you create a VM or after you create a VM.
Caution: Users with SSH keys in instance metadata can access VMs that block project SSH keys. Block project SSH keys from a VM during VM creationYou can block project SSH keys from VMs during VM creation, using the Google Cloud console, gcloud CLI, or Compute Engine API.
Caution: Users with SSH keys in instance metadata can access VMs that block project SSH keys. ConsoleTo create an instance and block it from accepting SSH keys stored in project metadata using the Google Cloud console, do the following:
In the Google Cloud console, go to the Create an instance page.
To block project SSH keys, do the following:
In the navigation menu, click Security.
Expand the Manage access section.
To disable OS Login, clear the Control VM access through IAM permissions checkbox.
Select the Block project-wide SSH keys checkbox.
Optional: Specify other configuration options. For more information, see Configuration options during instance creation.
To create and start the instance, click Create.
To create a VM and block it from accepting SSH keys stored in project metadata using the gcloud CLI, use the gcloud compute instances create
command:
gcloud compute instances create VM_NAME \ --metadata block-project-ssh-keys=TRUE
Replace VM_NAME
with the name of the new VM.
To create a VM and block it from accepting SSH keys stored in project metadata using the Compute Engine, construct a POST
request to the instances.insert
method:
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances
Replace the following:
PROJECT_ID
: the project IDZONE
: the zone of the VMIn the body of the request, provide usernames and public SSH keys in the items
property:
... { "items": [ { "key": "block-project-ssh-keys", "value": TRUE } ] } ...Block project SSH keys from a VM after VM creation
You can block project SSH keys from VMs after VM creation using the Google Cloud console, gcloud CLI, or Compute Engine API.
Caution: Users with SSH keys in instance metadata can access VMs that block project SSH keys. Permissions required for this taskTo perform this task, you must have the following permissions:
compute.projects.setCommonInstanceMetadata
To block VMs from accepting connections from SSH keys stored in project metadata using the Google Cloud console, do the following:
In the Google Cloud console, go to the VM instances page.
Click the name of the VM that you want to block project SSH keys for.
Click Edit.
Under SSH Keys, select the Block project-wide SSH keys checkbox.
When you have finished editing the connection setting for SSH keys, click Save.
To block VMs from accepting connections from SSH keys stored in project metadata using the gcloud CLI, do the following:
Run the gcloud compute instances add-metadata
command:
gcloud compute instances add-metadata VM_NAME --metadata block-project-ssh-keys=TRUE
Replace VM_NAME
with the name of the VM for which you want to block project-wide public SSH keys.
To block VMs from accepting connections from SSH keys stored in project metadata using the Compute Engine API, do the following:
Use the instances.get
method to get the fingerprint
from metadata.
GET https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/VM_NAME
Replace the following:
PROJECT_ID
: your project IDZONE
: the zone of the VM you're adding an SSH key forVM_NAME
: the VM you're adding an SSH key forThe response is similar to the following:
... "fingerprint": "utgYE_XWtE8=" ...
Use the instances.setMetadata
method to set block-project-ssh-keys
to TRUE
:
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/VM_NAME/setMetadata { "items": [ { "key": "block-project-ssh-keys", "value": TRUE } ] "fingerprint": "FINGERPRINT" }
Replace the following:
PROJECT_ID
is your project IDZONE
is the zone where your instance is locatedINSTANCE_NAME
is the instance where you want to block project-wide keys.FINGERPRINT
: the value of the fingerprint
from the response of the instances.get
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