80 lines
3.8 KiB
Markdown
80 lines
3.8 KiB
Markdown
---
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type: reference, howto
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stage: Manage
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group: Authentication and Authorization
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info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
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---
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# Restrict allowed SSH key technologies and minimum length **(FREE SELF)**
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`ssh-keygen` allows users to create RSA keys with as few as 768 bits, which
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falls well below recommendations from certain standards groups (such as the US
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NIST). Some organizations deploying GitLab need to enforce minimum key
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strength, either to satisfy internal security policy or for regulatory
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compliance.
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Similarly, certain standards groups recommend using RSA, ECDSA, ED25519,
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ECDSA_SK, or ED25519_SK over the older DSA, and administrators may need to
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limit the allowed SSH key algorithms.
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GitLab allows you to restrict the allowed SSH key technology as well as specify
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the minimum key length for each technology:
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1. On the top bar, select **Menu > Admin**.
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1. On the left sidebar, select **Settings > General** (`/admin/application_settings/general`).
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1. Expand the **Visibility and access controls** section:
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If a restriction is imposed on any key type, users cannot upload new SSH keys that don't meet the
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requirement. Any existing keys that don't meet it are disabled but not removed and users cannot
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pull or push code using them.
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An icon is visible to the user of a restricted key in the SSH keys section of their profile:
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Hovering over this icon tells you why the key is restricted.
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## Default settings
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By default, the GitLab.com and self-managed settings for the
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[supported key types](../user/ssh.md#supported-ssh-key-types) are:
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- RSA SSH keys are allowed.
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- DSA SSH keys are forbidden ([since GitLab 11.0](https://about.gitlab.com/releases/2018/06/22/gitlab-11-0-released/#support-for-dsa-ssh-keys)).
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- ECDSA SSH keys are allowed.
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- ED25519 SSH keys are allowed.
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- ECDSA_SK SSH keys are allowed (GitLab 14.8 and later).
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- ED25519_SK SSH keys are allowed (GitLab 14.8 and later).
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### Block banned or compromised keys **(FREE)**
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> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/24614) in GitLab 15.1 [with a flag](../administration/feature_flags.md) named `ssh_banned_key`. Enabled by default.
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FLAG:
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On self-managed GitLab, by default this feature is available. To hide the feature per user,
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ask an administrator to [disable the feature flag](../administration/feature_flags.md) named `ssh_banned_key`.
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On GitLab.com, this feature is available.
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When users attempt to [add a new SSH key](../user/ssh.md#add-an-ssh-key-to-your-gitlab-account)
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to GitLab accounts, the key is checked against a list of SSH keys which are known
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to be compromised. Users can't add keys from this list to any GitLab account.
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This restriction cannot be configured. This restriction exists because the private
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keys associated with the key pair are publicly known, and can be used to access
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accounts using the key pair.
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If your key is disallowed by this restriction, [generate a new SSH key pair](../user/ssh.md#generate-an-ssh-key-pair)
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to use instead.
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<!-- ## Troubleshooting
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Include any troubleshooting steps that you can foresee. If you know beforehand what issues
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one might have when setting this up, or when something is changed, or on upgrading, it's
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important to describe those, too. Think of things that may go wrong and include them here.
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This is important to minimize requests for support, and to avoid doc comments with
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questions that you know someone might ask.
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Each scenario can be a third-level heading, e.g. `### Getting error message X`.
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If you have none to add when creating a doc, leave this section in place
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but commented out to help encourage others to add to it in the future. -->
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