本頁說明 OS Login 服務及其運作原理。如要瞭解如何設定 OS 登入，請參閱設定 OS 登入。
使用 OS Login 可透過 IAM 管理執行個體的 SSH 存取權，而不用建立及管理個別的 SSH 金鑰。OS 登入可使 Linux 使用者身分在不同的 VM 執行個體中保持一致，因此建議您使用這個方式來管理多個 VM 或專案中的眾多使用者。
OS 登入的優點
OS 登入可將 Linux 使用者帳戶連結至您的 Google 身分，因而能簡化 SSH 存取權管理。管理員可在執行個體或專案層級，藉由設定 IAM 權限來輕鬆管理執行個體存取權。
OS 登入可提供以下優點：
自動化 Linux 帳戶生命週期管理：您可以直接將 Linux 使用者帳戶繫結至使用者的 Google 身分，以便讓相同的 Linux 帳戶資訊可以在同一專案或機構的所有執行個體中使用。
使用 Google IAM 進行精細的授權：專案和執行個體層級的管理員可使用 IAM 將 SSH 存取權授予使用者的 Google 身分，而不需要授予範圍更廣的權限集。舉例來說，您可以授予使用者登入系統、但不能執行 sudo 等指令的權限。Google 會檢查這些權限，以判斷使用者是否可登入 VM 執行個體。
自動更新權限：透過 OS 登入，當管理員變更 IAM 權限時，系統會自動更新權限。舉例來說，如果您將某個 Google 身分的 IAM 權限移除，則 VM 執行個體的存取權也會隨之撤銷。每次有使用者嘗試登入時，Google 都會檢查權限，以防有人擅自存取。
能夠匯入現有的 Linux 帳戶：管理員可以選擇從內部部署設定的 Active Directory (AD) 和輕量型目錄存取協定 (LDAP) 同步處理 Linux 帳戶資訊。例如，您可以確保使用者在您的 Cloud 和內部部署環境中都使用相同的使用者 ID (UID)。
與 Google 帳戶兩步驟驗證整合 - 您可以選擇要求 OS Login 使用者在連線至 VM 時，使用下列其中一種兩步驟驗證 (2FA) 方法或身分確認問題類型驗證身分：
[[["容易理解","easyToUnderstand","thumb-up"],["確實解決了我的問題","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["難以理解","hardToUnderstand","thumb-down"],["資訊或程式碼範例有誤","incorrectInformationOrSampleCode","thumb-down"],["缺少我需要的資訊/範例","missingTheInformationSamplesINeed","thumb-down"],["翻譯問題","translationIssue","thumb-down"],["其他","otherDown","thumb-down"]],["上次更新時間：2025-09-03 (世界標準時間)。"],[[["\u003cp\u003eOS Login streamlines SSH access management by linking Linux user accounts to Google identities, eliminating the need for individual SSH key management.\u003c/p\u003e\n"],["\u003cp\u003eIt leverages Google IAM for fine-grained authorization, enabling administrators to control access at the instance or project level and grant specific permissions, such as login without \u003ccode\u003esudo\u003c/code\u003e rights.\u003c/p\u003e\n"],["\u003cp\u003eOS Login automates Linux account lifecycle management, ensuring consistent user information across VMs, and automatically updates permissions based on changes in IAM settings.\u003c/p\u003e\n"],["\u003cp\u003eThe system supports integration with two-step verification methods and provides audit logging for monitoring VM connections.\u003c/p\u003e\n"],["\u003cp\u003eWhen OS Login is enabled, it configures VMs by managing \u003ccode\u003eauthorized_keys\u003c/code\u003e files, setting up an OpenSSH server with \u003ccode\u003eAuthorizedKeysCommand\u003c/code\u003e, configuring NSS functionality, and adding PAM configurations.\u003c/p\u003e\n"]]],[],null,["*** ** * ** ***\n\nThis page describes the OS Login service and how it works. To learn how to set\nup OS Login, see [Set up OS Login](/compute/docs/oslogin/set-up-oslogin).\n\nUse OS Login to manage SSH access to your instances using IAM\nwithout having to create and manage individual SSH keys. OS Login maintains a\nconsistent Linux user identity across VM instances and is the recommended way to\nmanage many users across multiple VMs or projects.\n| **Note:** When a user connects to a VM, that user can use all of the IAM permissions granted to the service account attached to the VM.\n\nBenefits of OS Login\n\nOS Login simplifies SSH access management by linking your Linux user account to\nyour Google identity. Administrators can easily manage access to instances at\neither an instance or project level by setting IAM permissions.\n\nOS Login provides the following benefits:\n\n- **Automatic Linux account lifecycle management** - You can directly tie\n a Linux user account to a user's Google identity so that the same Linux\n account information is used across all instances in the same project or\n organization.\n\n- **Fine grained authorization using Google IAM** - Project\n and instance-level administrators can use IAM to grant SSH\n access to a user's Google identity without granting a broader set of\n privileges. For example, you can grant a user permissions to log into the\n system, but not the ability to run commands such as `sudo`. Google checks\n these permissions to determine whether a user can log into a VM instance.\n\n- **Automatic permission updates** - With OS Login, permissions are updated\n automatically when an administrator changes IAM\n permissions. For example, if you remove IAM permissions from\n a Google identity, then access to VM instances is revoked. Google checks\n permissions for every login attempt to prevent unwanted access.\n\n- **Ability to import existing Linux accounts** - Administrators\n can choose to optionally synchronize Linux account information from\n Active Directory (AD) and Lightweight Directory Access Protocol (LDAP) that\n are set up on-premises. For example, you can ensure that users have the\n same user ID (UID) in both your Cloud and on-premises environments.\n\n- **Integration with Google Account two-step verification** - You can optionally\n require that OS Login users validate their identity using one of the following\n 2-step verification (2FA) methods or challenge types when connecting to VMs:\n\n - [Google Authenticator](https://support.google.com/accounts/answer/1066447)\n - Text message or phone call verification\n - [Phone prompts](https://support.google.com/accounts/answer/7026266)\n - [Security key one-time password (OTP)](https://gsuiteupdates.googleblog.com/2019/06/security-codes-and-security-keys.html)\n- **Support for certificate-based authentication (Preview)** - You can use SSH\n certificate authentication to connect to VMs that use OS Login. For more\n information, see\n [Require SSH certificates with OS Login](/compute/docs/oslogin/certificates).\n\n- **Integration with audit logging** - OS Login provides\n [audit logging](/compute/docs/oslogin/view-audit-logs) that you can use to\n monitor connections to VMs for OS Login users.\n\nHow OS Login works\n\nWhen OS Login is enabled, Compute Engine performs configurations\non VMs and the Google accounts of OS Login users.\n\nVM configuration\n\nWhen you enable OS Login, Compute Engine deletes the VM's `authorized_keys`\nfiles and configures an OpenSSH server. This server retrieves the SSH keys\nassociated with the Linux user account to authenticate the login attempt.\n\nYou can configure an `authorized_keys` file to provision access for a local user\naccount even when OS Login is enabled. SSH public keys that are configured in\nthe `authorized_keys` file are used to authenticate user login attempts by the\nlocal user. Local user accounts and OS Login users must have different usernames\nand UIDs.\n| **Note:** VMs that use OS Login can't use metadata-based SSH keys. If you enable OS Login for a VM, then the VM's guest agent ignores the keys stored in metadata. To learn more about using SSH keys with VMs, see [Add SSH keys to VMs](/compute/docs/connect/add-ssh-keys).\n\nFor more information about the OS Login components, review the\n[OS Login GitHub page](https://github.com/GoogleCloudPlatform/guest-oslogin#overview).\n\nUser account configuration\n\nOS Login configures your Google account with POSIX information, including a\nusername, when you do any of the following:\n\n- Connect to an OS Login-enabled VM using the Google Cloud console\n- Connect to an OS Login-enabled VM using the gcloud CLI\n- Import a public SSH key using the gcloud CLI\n- Import a public SSH key using the OS Login API\n\nOS Login configures POSIX accounts with the following values:\n\n- **Username:** a username in the format of\n \u003cvar translate=\"no\"\u003eUSERNAME\u003c/var\u003e`_`\u003cvar translate=\"no\"\u003eDOMAIN\u003c/var\u003e`_`\u003cvar translate=\"no\"\u003eSUFFIX\u003c/var\u003e.\n If the user is from a different Google Workspace organization than the\n one hosting their OS Login-enabled VMs, their username is prefixed\n with `ext_`. If the user is a service account, its username is prefixed with\n `sa_`.\n\n Cloud Identity administrators can\n [modify usernames](/compute/docs/oslogin/manage-oslogin-in-an-org#modify-users)\n and Google Workspace super administrators can change the username\n format to\n [remove the domain suffix](/compute/docs/oslogin/manage-oslogin-in-an-org#manage-oslogin-api).\n- **UID:** a unique, randomly-generated\n [POSIX-compliant](https://en.wikipedia.org/wiki/User_identifier) user ID.\n\n- **GID:** a POSIX-compliant group ID that is the same as the UID.\n\n- **Home directory:** the path to the user's home directory.\n\nOrganization administrators can configure and update a user's POSIX account\ninformation. For more information, see\n[Modify user accounts using the Directory API](/compute/docs/oslogin/manage-oslogin-in-an-org#modify-users).\n\nWhat's next\n\n- For step-by-step instructions, review one of the following:\n - [Setting up OS Login](/compute/docs/instances/managing-instance-access).\n - [Setting up OS Login with 2-step verification](/compute/docs/oslogin/setup-two-factor-authentication)\n- Review [Managing OS Login in an organization](/compute/docs/oslogin/manage-oslogin-in-an-org)\n- [Troubleshoot](/compute/docs/oslogin/troubleshoot-os-login) OS Login."]]
