Move SSH page into the user docs

This deals with how users can create and SSH
keys to their account, so it should be in
user/profile, not a top level directory by itself.

doc/administration/audit_event_streaming.md

@@ -155,7 +155,7 @@ On self-managed GitLab, by default this feature is not available. To make it ava
 
 Streaming audit events can be sent when signed-in users push or pull a project's remote Git repositories:
 
-- [Using SSH](../ssh/index.md).
+- [Using SSH](../user/ssh.md).
 - Using HTTP or HTTPS.
 - Using the **Download** button (**{download}**) in GitLab UI.
 

doc/administration/geo/replication/usage.md

@@ -27,7 +27,7 @@ Everything up-to-date
 ```
 
 NOTE:
-If you're using HTTPS instead of [SSH](../../../ssh/index.md) to push to the secondary,
+If you're using HTTPS instead of [SSH](../../../user/ssh.md) to push to the secondary,
 you can't store credentials in the URL like `user:password@URL`. Instead, you can use a
 [`.netrc` file](https://www.gnu.org/software/inetutils/manual/html_node/The-_002enetrc-file.html)
 for Unix-like operating systems or `_netrc` for Windows. In that case, the credentials

doc/administration/get_started.md

@@ -20,7 +20,7 @@ Authentication is the first step in making your installation secure.
     This one-time secret code is an additional safeguard that keeps intruders out, even if they have your password.
   - Add a backup email. If you lose access to your account, the GitLab Support team can help you more quickly.
   - Save or print your recovery codes. If you can't access your authentication device, you can use these recovery codes to sign in to your GitLab account.
-  - Add [an SSH key](../ssh/index.md) to your profile. You can generate new recovery codes as needed with SSH.
+  - Add [an SSH key](../user/ssh.md) to your profile. You can generate new recovery codes as needed with SSH.
   - Enable [personal access tokens](../user/profile/personal_access_tokens.md). When using 2FA, you can use these tokens to access the GitLab API.
 
 ## Projects and groups

doc/administration/operations/fast_ssh_key_lookup.md

@@ -83,7 +83,7 @@ file (start the line with a `#` to comment it), and from your local machine, att
 ssh -T git@gitlab.example.com
 ```
 
-A successful pull or [welcome message](../../ssh/index.md#verify-that-you-can-connect) would mean that GitLab was able to find the key in the database,
+A successful pull or [welcome message](../../user/ssh.md#verify-that-you-can-connect) would mean that GitLab was able to find the key in the database,
 since it is not present in the file anymore.
 
 NOTE:

doc/ci/examples/laravel_with_gitlab_and_envoy/index.md

@@ -104,7 +104,7 @@ sudo apt install acl
 
 ### Add SSH key
 
-Let's suppose we want to deploy our app to the production server from a private repository on GitLab. First, we need to [generate a new SSH key pair **with no passphrase**](../../../ssh/index.md) for the deployer user.
+Let's suppose we want to deploy our app to the production server from a private repository on GitLab. First, we need to [generate a new SSH key pair **with no passphrase**](../../../user/ssh.md) for the deployer user.
 
 After that, we need to copy the private key, which will be used to connect to our server as the deployer user with SSH, to be able to automate our deployment process:
 

doc/ci/ssh_keys/index.md

@@ -48,7 +48,7 @@ contained) and you want to deploy your code in a private server, you need a way
 to access it. In this case, you can use an SSH key pair.
 
 1. You first must create an SSH key pair. For more information, follow
-   the instructions to [generate an SSH key](../../ssh/index.md#generate-an-ssh-key-pair).
+   the instructions to [generate an SSH key](../../user/ssh.md#generate-an-ssh-key-pair).
    **Do not** add a passphrase to the SSH key, or the `before_script` will
    prompt for it.
 
@@ -124,7 +124,7 @@ on, and use that key for all projects that are run on this machine.
    ```
 
 1. Generate the SSH key pair as described in the instructions to
-   [generate an SSH key](../../ssh/index.md#generate-an-ssh-key-pair).
+   [generate an SSH key](../../user/ssh.md#generate-an-ssh-key-pair).
    **Do not** add a passphrase to the SSH key, or the `before_script` will
    prompt for it.
 

doc/gitlab-basics/index.md

@@ -21,7 +21,7 @@ This documentation is split into the following groups:
 
 The following are guides to basic GitLab functionality:
 
-- [Create and add your SSH public key](../ssh/index.md), for enabling Git over SSH.
+- [Create and add your SSH public key](../user/ssh.md), for enabling Git over SSH.
 - [Create a project](../user/project/working_with_projects.md#create-a-project), to start using GitLab.
 - [Create a group](../user/group/index.md#create-a-group), to combine and administer
   projects together.

doc/gitlab-basics/start-using-git.md

@@ -182,7 +182,7 @@ This connection requires you to add credentials. You can either use SSH or HTTPS
 
 Clone with SSH when you want to authenticate only one time.
 
-1. Authenticate with GitLab by following the instructions in the [SSH documentation](../ssh/index.md).
+1. Authenticate with GitLab by following the instructions in the [SSH documentation](../user/ssh.md).
 1. Go to your project's landing page and select **Clone**. Copy the URL for **Clone with SSH**.
 1. Open a terminal and go to the directory where you want to clone the files. Git automatically creates a folder with the repository name and downloads the files there.
 1. Run this command:

doc/install/azure/index.md

@@ -71,7 +71,7 @@ The first items you need to configure are the basic settings of the underlying v
    the user Azure uses to connect to the VM through SSH. By default, the user
    has root access.
 1. Determine if you want to provide your own SSH key or let Azure create one for you.
-   Read the [SSH documentation](../../ssh/index.md) to learn more about how to set up SSH
+   Read the [SSH documentation](../../user/ssh.md) to learn more about how to set up SSH
    public keys.
 
 Review your entered settings, and then proceed to the Disks tab.

doc/security/ssh_keys_restrictions.md

@@ -39,7 +39,7 @@ Hovering over this icon tells you why the key is restricted.
 ## Default settings
 
 By default, the GitLab.com and self-managed settings for the
-[supported key types](../ssh/index.md#supported-ssh-key-types) are:
+[supported key types](../user/ssh.md#supported-ssh-key-types) are:
 
 - RSA SSH keys are allowed.
 - 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)).

doc/security/two_factor_authentication.md

@@ -114,7 +114,7 @@ FLAG:
 On self-managed GitLab, by default this feature is not available. To make it available, ask an administrator to [enable the feature flag](../administration/feature_flags.md) named `two_factor_for_cli`. On GitLab.com, this feature is not available. The feature is not ready for production use. This feature flag also affects [session duration for Git Operations when 2FA is enabled](../user/admin_area/settings/account_and_limit_settings.md#customize-session-duration-for-git-operations-when-2fa-is-enabled).
 
 Two-factor authentication can be enforced for Git over SSH operations. However, we recommend using
-[ED25519_SK](../ssh/index.md#ed25519_sk-ssh-keys) or [ECDSA_SK](../ssh/index.md#ecdsa_sk-ssh-keys) SSH keys instead.
+[ED25519_SK](../user/ssh.md#ed25519_sk-ssh-keys) or [ECDSA_SK](../user/ssh.md#ecdsa_sk-ssh-keys) SSH keys instead.
 
 The one-time password (OTP) verification can be done using a command:
 

doc/ssh/index.md

 ---
-stage: Manage
-group: Authentication and Authorization
-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"
-type: howto, reference
+redirect_to: '../user/ssh.md'
+remove_date: '2022-06-18'
 ---
 
-# Use SSH keys to communicate with GitLab **(FREE)**
+This document was moved to [another location](../user/ssh.md).
 
-Git is a distributed version control system, which means you can work locally,
-then share or *push* your changes to a server. In this case, the server you push to is GitLab.
-
-GitLab uses the SSH protocol to securely communicate with Git.
-When you use SSH keys to authenticate to the GitLab remote server,
-you don't need to supply your username and password each time.
-
-## Prerequisites
-
-To use SSH to communicate with GitLab, you need:
-
-- The OpenSSH client, which comes pre-installed on GNU/Linux, macOS, and Windows 10.
-- SSH version 6.5 or later. Earlier versions used an MD5 signature, which is not secure.
-
-To view the version of SSH installed on your system, run `ssh -V`.
-
-## Supported SSH key types
-
-To communicate with GitLab, you can use the following SSH key types:
-
-- [ED25519](#ed25519-ssh-keys)
-- [ED25519_SK](#ed25519_sk-ssh-keys) (Available in GitLab 14.8 and later.)
-- [ECDSA_SK](#ecdsa_sk-ssh-keys) (Available in GitLab 14.8 and later.)
-- [RSA](#rsa-ssh-keys)
-- DSA ([Deprecated](https://about.gitlab.com/releases/2018/06/22/gitlab-11-0-released/#support-for-dsa-ssh-keys) in GitLab 11.0.)
-- ECDSA (As noted in [Practical Cryptography With Go](https://leanpub.com/gocrypto/read#leanpub-auto-ecdsa), the security issues related to DSA also apply to ECDSA.)
-
-Administrators can [restrict which keys are permitted and their minimum lengths](../security/ssh_keys_restrictions.md).
-
-### ED25519 SSH keys
-
-The book [Practical Cryptography With Go](https://leanpub.com/gocrypto/read#leanpub-auto-chapter-5-digital-signatures)
-suggests that [ED25519](https://ed25519.cr.yp.to/) keys are more secure and performant than RSA keys.
-
-OpenSSH 6.5 introduced ED25519 SSH keys in 2014 and they should be available on most
-operating systems.
-
-### ED25519_SK SSH keys
-
-> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/78934) in GitLab 14.8.
-
-To use ED25519_SK SSH keys on GitLab, your local client and GitLab server
-must have [OpenSSH 8.2](https://www.openssh.com/releasenotes.html#8.2) or later installed.
-
-### ECDSA_SK SSH keys
-
-> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/78934) in GitLab 14.8.
-
-To use ECDSA_SK SSH keys on GitLab, your local client and GitLab server
-must have [OpenSSH 8.2](https://www.openssh.com/releasenotes.html#8.2) or later installed.
-
-### RSA SSH keys
-
-Available documentation suggests that ED25519 is more secure than RSA.
-
-If you use an RSA key, the US National Institute of Science and Technology in
-[Publication 800-57 Part 3 (PDF)](https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-57Pt3r1.pdf)
-recommends a key size of at least 2048 bits. The default key size depends on your version of `ssh-keygen`.
-Review the `man` page for your installed `ssh-keygen` command for details.
-
-## See if you have an existing SSH key pair
-
-Before you create a key pair, see if a key pair already exists.
-
-1. On Windows, Linux, or macOS, go to your home directory.
-1. Go to the `.ssh/` subdirectory. If the `.ssh/` subdirectory doesn't exist,
-   you are either not in the home directory, or you haven't used `ssh` before.
-   In the latter case, you need to [generate an SSH key pair](#generate-an-ssh-key-pair).
-1. See if a file with one of the following formats exists:
-
-   | Algorithm | Public key | Private key |
-   | --------- | ---------- | ----------- |
-   |  ED25519 (preferred)  | `id_ed25519.pub` | `id_ed25519` |
-   |  ED25519_SK | `id_ed25519_sk.pub` | `id_ed25519_sk` |
-   |  ECDSA_SK | `id_ecdsa_sk.pub` | `id_ecdsa_sk` |
-   |  RSA (at least 2048-bit key size)     | `id_rsa.pub` | `id_rsa` |
-   |  DSA (deprecated)      | `id_dsa.pub` | `id_dsa` |
-   |  ECDSA    | `id_ecdsa.pub` | `id_ecdsa` |
-
-## Generate an SSH key pair
-
-If you do not have an existing SSH key pair, generate a new one.
-
-1. Open a terminal.
-1. Type `ssh-keygen -t` followed by the key type and an optional comment.
-   This comment is included in the `.pub` file that's created.
-   You may want to use an email address for the comment.
-
-   For example, for ED25519:
-
-   ```shell
-   ssh-keygen -t ed25519 -C "<comment>"
-   ```
-
-   For 2048-bit RSA:
-
-   ```shell
-   ssh-keygen -t rsa -b 2048 -C "<comment>"
-   ```
-
-1. Press Enter. Output similar to the following is displayed:
-
-   ```plaintext
-   Generating public/private ed25519 key pair.
-   Enter file in which to save the key (/home/user/.ssh/id_ed25519):
-   ```
-
-1. Accept the suggested filename and directory, unless you are generating a [deploy key](../user/project/deploy_keys/index.md)
-   or want to save in a specific directory where you store other keys.
-
-   You can also dedicate the SSH key pair to a [specific host](#configure-ssh-to-point-to-a-different-directory).
-
-1. Specify a [passphrase](https://www.ssh.com/academy/ssh/passphrase):
-
-   ```plaintext
-   Enter passphrase (empty for no passphrase):
-   Enter same passphrase again:
-   ```
-
-1. A confirmation is displayed, including information about where your files are stored.
-
-A public and private key are generated.
-[Add the public SSH key to your GitLab account](#add-an-ssh-key-to-your-gitlab-account) and keep
-the private key secure.
-
-### Configure SSH to point to a different directory
-
-If you did not save your SSH key pair in the default directory,
-configure your SSH client to point to the directory where the private key is stored.
-
-1. Open a terminal and run this command:
-
-   ```shell
-   eval $(ssh-agent -s)
-   ssh-add <directory to private SSH key>
-   ```
-
-1. Save these settings in the `~/.ssh/config` file. For example:
-
-   ```conf
-   # GitLab.com
-   Host gitlab.com
-     PreferredAuthentications publickey
-     IdentityFile ~/.ssh/gitlab_com_rsa
-
-   # Private GitLab instance
-   Host gitlab.company.com
-     PreferredAuthentications publickey
-     IdentityFile ~/.ssh/example_com_rsa
-   ```
-
-   For more information on these settings, see the [`man ssh_config`](https://man.openbsd.org/ssh_config) page in the SSH configuration manual.
-
-Public SSH keys must be unique to GitLab because they bind to your account.
-Your SSH key is the only identifier you have when you push code with SSH.
-It must uniquely map to a single user.
-
-### Update your SSH key passphrase
-
-You can update the passphrase for your SSH key.
-
-1. Open a terminal and run this command:
-
-   ```shell
-   ssh-keygen -p -f /path/to/ssh_key
-   ```
-
-1. At the prompts, type the passphrase and press Enter.
-
-### Upgrade your RSA key pair to a more secure format
-
-If your version of OpenSSH is between 6.5 and 7.8,
-you can save your private RSA SSH keys in a more secure
-OpenSSH format.
-
-1. Open a terminal and run this command:
-
-   ```shell
-   ssh-keygen -o -f ~/.ssh/id_rsa
-   ```
-
-   Alternatively, you can generate a new RSA key with the more secure encryption format with
-   the following command:
-
-   ```shell
-   ssh-keygen -o -t rsa -b 4096 -C "<comment>"
-   ```
-
-## Generate an SSH key pair for a FIDO/U2F hardware security key
-
-To generate ED25519_SK or ECDSA_SK SSH keys, you must use OpenSSH 8.2 or later.
-
-1. Insert a hardware security key into your computer.
-1. Open a terminal.
-1. Type `ssh-keygen -t` followed by the key type and an optional comment.
-   This comment is included in the `.pub` file that's created.
-   You may want to use an email address for the comment.
-
-   For example, for ED25519_SK:
-
-   ```shell
-   ssh-keygen -t ed25519-sk -C "<comment>"
-   ```
-
-   For ECDSA_SK:
-
-   ```shell
-   ssh-keygen -t ecdsa-sk -C "<comment>"
-   ```
-
-   If your security key supports FIDO2 resident keys, you can enable this when
-   creating your SSH key:
-
-   ```shell
-   ssh-keygen -t ed25519-sk -O resident -C "<comment>"
-   ```
-
-   `-O resident` indicates that the key should be stored on the FIDO authenticator itself.
-   Resident key is easier to import to a new computer because it can be loaded directly
-   from the security key by [`ssh-add -K`](https://man.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man1/ssh-add.1#K)
-   or  [`ssh-keygen -K`](https://man.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man1/ssh-keygen#K).
-
-1. Select Enter. Output similar to the following is displayed:
-
-   ```plaintext
-   Generating public/private ed25519-sk key pair.
-   You may need to touch your authenticator to authorize key generation.
-   ```
-
-1. Touch the button on the hardware security key.
-
-1. Accept the suggested filename and directory:
-
-   ```plaintext
-   Enter file in which to save the key (/home/user/.ssh/id_ed25519_sk):
-   ```
-
-1. Specify a [passphrase](https://www.ssh.com/academy/ssh/passphrase):
-
-   ```plaintext
-   Enter passphrase (empty for no passphrase):
-   Enter same passphrase again:
-   ```
-
-1. A confirmation is displayed, including information about where your files are stored.
-
-A public and private key are generated.
-[Add the public SSH key to your GitLab account](#add-an-ssh-key-to-your-gitlab-account).
-
-## Add an SSH key to your GitLab account
-
-To use SSH with GitLab, copy your public key to your GitLab account.
-
-1. Copy the contents of your public key file. You can do this manually or use a script.
-   For example, to copy an ED25519 key to the clipboard:
-
-   **macOS:**
-
-   ```shell
-   tr -d '\n' < ~/.ssh/id_ed25519.pub | pbcopy
-   ```
-
-   **Linux** (requires the `xclip` package):
-
-   ```shell
-   xclip -sel clip < ~/.ssh/id_ed25519.pub
-   ```
-
-   **Git Bash on Windows:**
-
-   ```shell
-   cat ~/.ssh/id_ed25519.pub | clip
-   ```
-
-   Replace `id_ed25519.pub` with your filename. For example, use `id_rsa.pub` for RSA.
-
-1. Sign in to GitLab.
-1. On the top bar, in the top right corner, select your avatar.
-1. Select **Preferences**.
-1. On the left sidebar, select **SSH Keys**.
-1. In the **Key** box, paste the contents of your public key.
-   If you manually copied the key, make sure you copy the entire key,
-   which starts with `ssh-rsa`, `ssh-dss`, `ecdsa-sha2-nistp256`, `ecdsa-sha2-nistp384`, `ecdsa-sha2-nistp521`,
-   `ssh-ed25519`, `sk-ecdsa-sha2-nistp256@openssh.com`, or `sk-ssh-ed25519@openssh.com`, and may end with a comment.
-1. In the **Title** box, type a description, like `Work Laptop` or
-   `Home Workstation`.
-1. Optional. In the **Expires at** box, select an expiration date. ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/36243) in GitLab 12.9.)
-   In:
-   - GitLab 13.12 and earlier, the expiration date is informational only. It doesn't prevent
-     you from using the key. Administrators can view expiration dates and use them for
-     guidance when [deleting keys](../user/admin_area/credentials_inventory.md#delete-a-users-ssh-key).
-   - GitLab 14.0 and later, the expiration date is enforced. Administrators can
-     [allow expired keys to be used](../user/admin_area/settings/account_and_limit_settings.md#allow-expired-ssh-keys-to-be-used-deprecated).
-   - GitLab checks all SSH keys at 02:00 AM UTC every day. It emails an expiration notice for all SSH keys that expire on the current date. ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/322637) in GitLab 13.11.)
-   - GitLab checks all SSH keys at 01:00 AM UTC every day. It emails an expiration notice for all SSH keys that are scheduled to expire seven days from now. ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/322637) in GitLab 13.11.)
-1. Select **Add key**.
-
-## Verify that you can connect
-
-Verify that your SSH key was added correctly.
-
-1. For GitLab.com, to ensure you're connecting to the correct server, confirm the
-   [SSH host keys fingerprints](../user/gitlab_com/index.md#ssh-host-keys-fingerprints).
-1. Open a terminal and run this command, replacing `gitlab.example.com` with your GitLab instance URL:
-
-   ```shell
-   ssh -T git@gitlab.example.com
-   ```
-
-1. If this is the first time you connect, you should verify the
-   authenticity of the GitLab host. If you see a message like:
-
-   ```plaintext
-   The authenticity of host 'gitlab.example.com (35.231.145.151)' can't be established.
-   ECDSA key fingerprint is SHA256:HbW3g8zUjNSksFbqTiUWPWg2Bq1x8xdGUrliXFzSnUw.
-   Are you sure you want to continue connecting (yes/no)? yes
-   Warning: Permanently added 'gitlab.example.com' (ECDSA) to the list of known hosts.
-   ```
-
-   Type `yes` and press Enter.
-
-1. Run the `ssh -T git@gitlab.example.com` command again. You should receive a _Welcome to GitLab, `@username`!_ message.
-
-If the welcome message doesn't appear, you can troubleshoot by running `ssh`
-in verbose mode:
-
-```shell
-ssh -Tvvv git@gitlab.example.com
-```
-
-## Use different keys for different repositories
-
-You can use a different key for each repository.
-
-Open a terminal and run this command:
-
-```shell
-git config core.sshCommand "ssh -o IdentitiesOnly=yes -i ~/.ssh/private-key-filename-for-this-repository -F /dev/null"
-```
-
-This command does not use the SSH Agent and requires Git 2.10 or later. For more information
-on `ssh` command options, see the `man` pages for both `ssh` and `ssh_config`.
-
-## Use different accounts on a single GitLab instance
-
-You can use multiple accounts to connect to a single instance of GitLab.
-You can do this by using the command in the [previous topic](#use-different-keys-for-different-repositories).
-However, even if you set `IdentitiesOnly` to `yes`, you cannot sign in if an `IdentityFile` exists
-outside of a `Host` block.
-
-Instead, you can assign aliases to hosts in the `~.ssh/config` file.
-
-- For the `Host`, use an alias like `user_1.gitlab.com` and
-  `user_2.gitlab.com`. Advanced configurations
-  are more difficult to maintain, and these strings are easier to
-  understand when you use tools like `git remote`.
-- For the `IdentityFile`, use the path the private key.
-
-```conf
-# User1 Account Identity
-Host <user_1.gitlab.com>
-  Hostname gitlab.com
-  PreferredAuthentications publickey
-  IdentityFile ~/.ssh/<example_ssh_key1>
-
-# User2 Account Identity
-Host <user_2.gitlab.com>
-  Hostname gitlab.com
-  PreferredAuthentications publickey
-  IdentityFile ~/.ssh/<example_ssh_key2>
-```
-
-Now, to clone a repository for `user_1`, use `user_1.gitlab.com` in the `git clone` command:
-
-```shell
-git clone git@<user_1.gitlab.com>:gitlab-org/gitlab.git
-```
-
-To update a previously-cloned repository that is aliased as `origin`:
-
-```shell
-git remote set-url origin git@<user_1.gitlab.com>:gitlab-org/gitlab.git
-```
-
-NOTE:
-Private and public keys contain sensitive data. Ensure the permissions
-on the files make them readable to you but not accessible to others.
-
-## Configure two-factor authentication (2FA)
-
-You can set up two-factor authentication (2FA) for
-[Git over SSH](../security/two_factor_authentication.md#2fa-for-git-over-ssh-operations). We recommend using
-[ED25519_SK](#ed25519_sk-ssh-keys) or [ECDSA_SK](#ecdsa_sk-ssh-keys) SSH keys.
-
-## Use EGit on Eclipse
-
-If you are using [EGit](https://www.eclipse.org/egit/), you can [add your SSH key to Eclipse](https://wiki.eclipse.org/EGit/User_Guide#Eclipse_SSH_Configuration).
-
-## Use SSH on Microsoft Windows
-
-If you're running Windows 10, you can either use the [Windows Subsystem for Linux (WSL)](https://docs.microsoft.com/en-us/windows/wsl/install)
-with [WSL 2](https://docs.microsoft.com/en-us/windows/wsl/install#update-to-wsl-2) which
-has both `git` and `ssh` preinstalled, or install [Git for Windows](https://gitforwindows.org) to
-use SSH through Powershell.
-
-The SSH key generated in WSL is not directly available for Git for Windows, and vice versa,
-as both have a different home directory:
-
-- WSL: `/home/<user>`
-- Git for Windows: `C:\Users\<user>`
-
-You can either copy over the `.ssh/` directory to use the same key, or generate a key in each environment.
-
-Alternative tools include:
-
-- [Cygwin](https://www.cygwin.com)
-- [PuttyGen](https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html)
-
-## Overriding SSH settings on the GitLab server
-
-GitLab integrates with the system-installed SSH daemon and designates a user
-(typically named `git`) through which all access requests are handled. Users
-who connect to the GitLab server over SSH are identified by their SSH key instead
-of their username.
-
-SSH *client* operations performed on the GitLab server are executed as this
-user. You can modify this SSH configuration. For example, you can specify
-a private SSH key for this user to use for authentication requests. However, this practice
-is **not supported** and is strongly discouraged as it presents significant
-security risks.
-
-GitLab checks for this condition, and directs you
-to this section if your server is configured this way. For example:
-
-```shell
-$ gitlab-rake gitlab:check
-
-Git user has default SSH configuration? ... no
-  Try fixing it:
-  mkdir ~/gitlab-check-backup-1504540051
-  sudo mv /var/lib/git/.ssh/id_rsa ~/gitlab-check-backup-1504540051
-  sudo mv /var/lib/git/.ssh/id_rsa.pub ~/gitlab-check-backup-1504540051
-  For more information see:
-  [Overriding SSH settings on the GitLab server](#overriding-ssh-settings-on-the-gitlab-server)
-  Please fix the error above and rerun the checks.
-```
-
-Remove the custom configuration as soon as you can. These customizations
-are **explicitly not supported** and may stop working at any time.
-
-## Troubleshooting
-
-### Password prompt with `git clone`
-
-When you run `git clone`, you may be prompted for a password, like `git@gitlab.example.com's password:`.
-This indicates that something is wrong with your SSH setup.
-
-- Ensure that you generated your SSH key pair correctly and added the public SSH
-  key to your GitLab profile.
-- Try to manually register your private SSH key by using `ssh-agent`.
-- Try to debug the connection by running `ssh -Tv git@example.com`.
-  Replace `example.com` with your GitLab URL.
-
-### `Could not resolve hostname` error
-
-You may receive the following error when [verifying that you can connect](#verify-that-you-can-connect):
-
-```shell
-ssh: Could not resolve hostname gitlab.example.com: nodename nor servname provided, or not known
-```
-
-If you receive this error, restart your terminal and try the command again.
-
-### `Key enrollment failed: invalid format` error
-
-You may receive the following error when [generating an SSH key pair for a FIDO/U2F hardware security key](#generate-an-ssh-key-pair-for-a-fidou2f-hardware-security-key):
-
-```shell
-Key enrollment failed: invalid format
-```
-
-You can troubleshoot this by trying the following:
-
-- Run the `ssh-keygen` command using `sudo`.
-- Verify your IDO/U2F hardware security key supports
-  the key type provided.
-- Verify the version of OpenSSH is 8.2 or greater by
-  running `ssh -v`.
+<!-- This redirect file can be deleted after <2022-06-18>. -->
+<!-- Redirects that point to other docs in the same project expire in three months. -->
+<!-- Redirects that point to docs in a different project or site (for example, link is not relative and starts with `https:`) expire in one year. -->
+<!-- Before deletion, see: https://docs.gitlab.com/ee/development/documentation/redirects.html -->

doc/topics/authentication/index.md

@@ -10,7 +10,7 @@ This page gathers all the resources for the topic **Authentication** within GitL
 
 ## GitLab users
 
-- [SSH](../../ssh/index.md)
+- [SSH](../../user/ssh.md)
 - [Two-factor authentication](../../user/profile/account/two_factor_authentication.md)
 - [Why do I keep getting signed out?](../../user/profile/index.md#why-do-i-keep-getting-signed-out)
 - **Articles:**

doc/topics/git/how_to_install_git/index.md

@@ -79,7 +79,7 @@ Go to the [Git website](https://git-scm.com/), and then download and install Git
 
 ## After you install Git
 
-After you successfully install Git on your computer, read about [adding an SSH key to GitLab](../../../ssh/index.md).
+After you successfully install Git on your computer, read about [adding an SSH key to GitLab](../../../user/ssh.md).
 
 <!-- ## Troubleshooting
 

doc/topics/git/troubleshooting_git.md

@@ -45,7 +45,7 @@ set to 50MB. The default is 1MB.
 **If pushing over SSH**, first check your SSH configuration as 'Broken pipe'
 errors can sometimes be caused by underlying issues with SSH (such as
 authentication). Make sure that SSH is correctly configured by following the
-instructions in the [SSH troubleshooting](../../ssh/index.md#password-prompt-with-git-clone) documentation.
+instructions in the [SSH troubleshooting](../../user/ssh.md#password-prompt-with-git-clone) documentation.
 
 If you're a GitLab administrator with server access, you can also prevent
 session timeouts by configuring SSH `keep-alive` on the client or the server.

doc/topics/set_up_organization.md

@@ -13,5 +13,5 @@ and give everyone access to the projects they need.
 - [Workspace](../user/workspace/index.md) _(Coming soon)_
 - [Groups](../user/group/index.md)
 - [User account options](../user/profile/index.md)
-- [SSH keys](../ssh/index.md)
+- [SSH keys](../user/ssh.md)
 - [GitLab.com settings](../user/gitlab_com/index.md)

doc/user/admin_area/settings/account_and_limit_settings.md

@@ -199,7 +199,7 @@ To set a limit on how long these sessions are valid:
 > - [Generally available](https://gitlab.com/gitlab-org/gitlab/-/issues/1007) in GitLab 14.7. [Feature flag ff_limit_ssh_key_lifetime](https://gitlab.com/gitlab-org/gitlab/-/issues/347408) removed.
 
 Users can optionally specify a lifetime for
-[SSH keys](../../../ssh/index.md).
+[SSH keys](../../ssh.md).
 This lifetime is not a requirement, and can be set to any arbitrary number of days.
 
 SSH keys are user credentials to access GitLab.

doc/user/profile/index.md

@@ -438,6 +438,6 @@ Without the `config.extend_remember_period` flag, you would be forced to sign in
 - [Receive emails for sign-ins from unknown IP addresses or devices](unknown_sign_in_notification.md)
 - Manage applications that can [use GitLab as an OAuth provider](../../integration/oauth_provider.md#introduction-to-oauth)
 - Manage [personal access tokens](personal_access_tokens.md) to access your account via API and authorized applications
-- Manage [SSH keys](../../ssh/index.md) to access your account via SSH
+- Manage [SSH keys](../ssh.md) to access your account via SSH
 - Change your [syntax highlighting theme](preferences.md#syntax-highlighting-theme)
 - [View your active sessions](active_sessions.md) and revoke any of them if necessary

doc/user/project/deploy_keys/index.md

@@ -69,7 +69,7 @@ The deploy keys available are listed:
 Prerequisites:
 
 - You must have at least the Maintainer role for the project.
-- [Generate an SSH key pair](../../../ssh/index.md#generate-an-ssh-key-pair). Put the private SSH
+- [Generate an SSH key pair](../../ssh.md#generate-an-ssh-key-pair). Put the private SSH
   key on the host that requires access to the repository.
 
 1. On the top bar, select **Menu > Projects** and find your project.
@@ -87,7 +87,7 @@ name and permissions.
 Prerequisites:
 
 - You must have administrator access.
-- [Generate an SSH key pair](../../../ssh/index.md#generate-an-ssh-key-pair). Put the private SSH
+- [Generate an SSH key pair](../../ssh.md#generate-an-ssh-key-pair). Put the private SSH
   key on the host that requires access to the repository.
 
 To create a public deploy key:

doc/user/project/working_with_projects.md

@@ -206,8 +206,8 @@ used or renamed project, use the [UI](#create-a-project) or the [Projects API](.
 
 Prerequisites:
 
-- To push with SSH, you must have [an SSH key](../../ssh/index.md) that is
-  [added to your GitLab account](../../ssh/index.md#add-an-ssh-key-to-your-gitlab-account).
+- To push with SSH, you must have [an SSH key](../ssh.md) that is
+  [added to your GitLab account](../ssh.md#add-an-ssh-key-to-your-gitlab-account).
 - You must have permission to add new projects to a namespace. To check if you have permission:
 
   1. On the top bar, select **Menu > Projects**.

doc/user/ssh.md

+---
+stage: Manage
+group: Authentication and Authorization
+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"
+type: howto, reference
+---
+
+# Use SSH keys to communicate with GitLab **(FREE)**
+
+Git is a distributed version control system, which means you can work locally,
+then share or *push* your changes to a server. In this case, the server you push to is GitLab.
+
+GitLab uses the SSH protocol to securely communicate with Git.
+When you use SSH keys to authenticate to the GitLab remote server,
+you don't need to supply your username and password each time.
+
+## Prerequisites
+
+To use SSH to communicate with GitLab, you need:
+
+- The OpenSSH client, which comes pre-installed on GNU/Linux, macOS, and Windows 10.
+- SSH version 6.5 or later. Earlier versions used an MD5 signature, which is not secure.
+
+To view the version of SSH installed on your system, run `ssh -V`.
+
+## Supported SSH key types
+
+To communicate with GitLab, you can use the following SSH key types:
+
+- [ED25519](#ed25519-ssh-keys)
+- [ED25519_SK](#ed25519_sk-ssh-keys) (Available in GitLab 14.8 and later.)
+- [ECDSA_SK](#ecdsa_sk-ssh-keys) (Available in GitLab 14.8 and later.)
+- [RSA](#rsa-ssh-keys)
+- DSA ([Deprecated](https://about.gitlab.com/releases/2018/06/22/gitlab-11-0-released/#support-for-dsa-ssh-keys) in GitLab 11.0.)
+- ECDSA (As noted in [Practical Cryptography With Go](https://leanpub.com/gocrypto/read#leanpub-auto-ecdsa), the security issues related to DSA also apply to ECDSA.)
+
+Administrators can [restrict which keys are permitted and their minimum lengths](../security/ssh_keys_restrictions.md).
+
+### ED25519 SSH keys
+
+The book [Practical Cryptography With Go](https://leanpub.com/gocrypto/read#leanpub-auto-chapter-5-digital-signatures)
+suggests that [ED25519](https://ed25519.cr.yp.to/) keys are more secure and performant than RSA keys.
+
+OpenSSH 6.5 introduced ED25519 SSH keys in 2014 and they should be available on most
+operating systems.
+
+### ED25519_SK SSH keys
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/78934) in GitLab 14.8.
+
+To use ED25519_SK SSH keys on GitLab, your local client and GitLab server
+must have [OpenSSH 8.2](https://www.openssh.com/releasenotes.html#8.2) or later installed.
+
+### ECDSA_SK SSH keys
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/78934) in GitLab 14.8.
+
+To use ECDSA_SK SSH keys on GitLab, your local client and GitLab server
+must have [OpenSSH 8.2](https://www.openssh.com/releasenotes.html#8.2) or later installed.
+
+### RSA SSH keys
+
+Available documentation suggests that ED25519 is more secure than RSA.
+
+If you use an RSA key, the US National Institute of Science and Technology in
+[Publication 800-57 Part 3 (PDF)](https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-57Pt3r1.pdf)
+recommends a key size of at least 2048 bits. The default key size depends on your version of `ssh-keygen`.
+Review the `man` page for your installed `ssh-keygen` command for details.
+
+## See if you have an existing SSH key pair
+
+Before you create a key pair, see if a key pair already exists.
+
+1. On Windows, Linux, or macOS, go to your home directory.
+1. Go to the `.ssh/` subdirectory. If the `.ssh/` subdirectory doesn't exist,
+   you are either not in the home directory, or you haven't used `ssh` before.
+   In the latter case, you need to [generate an SSH key pair](#generate-an-ssh-key-pair).
+1. See if a file with one of the following formats exists:
+
+   | Algorithm | Public key | Private key |
+   | --------- | ---------- | ----------- |
+   |  ED25519 (preferred)  | `id_ed25519.pub` | `id_ed25519` |
+   |  ED25519_SK | `id_ed25519_sk.pub` | `id_ed25519_sk` |
+   |  ECDSA_SK | `id_ecdsa_sk.pub` | `id_ecdsa_sk` |
+   |  RSA (at least 2048-bit key size)     | `id_rsa.pub` | `id_rsa` |
+   |  DSA (deprecated)      | `id_dsa.pub` | `id_dsa` |
+   |  ECDSA    | `id_ecdsa.pub` | `id_ecdsa` |
+
+## Generate an SSH key pair
+
+If you do not have an existing SSH key pair, generate a new one.
+
+1. Open a terminal.
+1. Type `ssh-keygen -t` followed by the key type and an optional comment.
+   This comment is included in the `.pub` file that's created.
+   You may want to use an email address for the comment.
+
+   For example, for ED25519:
+
+   ```shell
+   ssh-keygen -t ed25519 -C "<comment>"
+   ```
+
+   For 2048-bit RSA:
+
+   ```shell
+   ssh-keygen -t rsa -b 2048 -C "<comment>"
+   ```
+
+1. Press Enter. Output similar to the following is displayed:
+
+   ```plaintext
+   Generating public/private ed25519 key pair.
+   Enter file in which to save the key (/home/user/.ssh/id_ed25519):
+   ```
+
+1. Accept the suggested filename and directory, unless you are generating a [deploy key](project/deploy_keys/index.md)
+   or want to save in a specific directory where you store other keys.
+
+   You can also dedicate the SSH key pair to a [specific host](#configure-ssh-to-point-to-a-different-directory).
+
+1. Specify a [passphrase](https://www.ssh.com/academy/ssh/passphrase):
+
+   ```plaintext
+   Enter passphrase (empty for no passphrase):
+   Enter same passphrase again:
+   ```
+
+1. A confirmation is displayed, including information about where your files are stored.
+
+A public and private key are generated.
+[Add the public SSH key to your GitLab account](#add-an-ssh-key-to-your-gitlab-account) and keep
+the private key secure.
+
+### Configure SSH to point to a different directory
+
+If you did not save your SSH key pair in the default directory,
+configure your SSH client to point to the directory where the private key is stored.
+
+1. Open a terminal and run this command:
+
+   ```shell
+   eval $(ssh-agent -s)
+   ssh-add <directory to private SSH key>
+   ```
+
+1. Save these settings in the `~/.ssh/config` file. For example:
+
+   ```conf
+   # GitLab.com
+   Host gitlab.com
+     PreferredAuthentications publickey
+     IdentityFile ~/.ssh/gitlab_com_rsa
+
+   # Private GitLab instance
+   Host gitlab.company.com
+     PreferredAuthentications publickey
+     IdentityFile ~/.ssh/example_com_rsa
+   ```
+
+   For more information on these settings, see the [`man ssh_config`](https://man.openbsd.org/ssh_config) page in the SSH configuration manual.
+
+Public SSH keys must be unique to GitLab because they bind to your account.
+Your SSH key is the only identifier you have when you push code with SSH.
+It must uniquely map to a single user.
+
+### Update your SSH key passphrase
+
+You can update the passphrase for your SSH key.
+
+1. Open a terminal and run this command:
+
+   ```shell
+   ssh-keygen -p -f /path/to/ssh_key
+   ```
+
+1. At the prompts, type the passphrase and press Enter.
+
+### Upgrade your RSA key pair to a more secure format
+
+If your version of OpenSSH is between 6.5 and 7.8,
+you can save your private RSA SSH keys in a more secure
+OpenSSH format.
+
+1. Open a terminal and run this command:
+
+   ```shell
+   ssh-keygen -o -f ~/.ssh/id_rsa
+   ```
+
+   Alternatively, you can generate a new RSA key with the more secure encryption format with
+   the following command:
+
+   ```shell
+   ssh-keygen -o -t rsa -b 4096 -C "<comment>"
+   ```
+
+## Generate an SSH key pair for a FIDO/U2F hardware security key
+
+To generate ED25519_SK or ECDSA_SK SSH keys, you must use OpenSSH 8.2 or later.
+
+1. Insert a hardware security key into your computer.
+1. Open a terminal.
+1. Type `ssh-keygen -t` followed by the key type and an optional comment.
+   This comment is included in the `.pub` file that's created.
+   You may want to use an email address for the comment.
+
+   For example, for ED25519_SK:
+
+   ```shell
+   ssh-keygen -t ed25519-sk -C "<comment>"
+   ```
+
+   For ECDSA_SK:
+
+   ```shell
+   ssh-keygen -t ecdsa-sk -C "<comment>"
+   ```
+
+   If your security key supports FIDO2 resident keys, you can enable this when
+   creating your SSH key:
+
+   ```shell
+   ssh-keygen -t ed25519-sk -O resident -C "<comment>"
+   ```
+
+   `-O resident` indicates that the key should be stored on the FIDO authenticator itself.
+   Resident key is easier to import to a new computer because it can be loaded directly
+   from the security key by [`ssh-add -K`](https://man.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man1/ssh-add.1#K)
+   or  [`ssh-keygen -K`](https://man.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man1/ssh-keygen#K).
+
+1. Select Enter. Output similar to the following is displayed:
+
+   ```plaintext
+   Generating public/private ed25519-sk key pair.
+   You may need to touch your authenticator to authorize key generation.
+   ```
+
+1. Touch the button on the hardware security key.
+
+1. Accept the suggested filename and directory:
+
+   ```plaintext
+   Enter file in which to save the key (/home/user/.ssh/id_ed25519_sk):
+   ```
+
+1. Specify a [passphrase](https://www.ssh.com/academy/ssh/passphrase):
+
+   ```plaintext
+   Enter passphrase (empty for no passphrase):
+   Enter same passphrase again:
+   ```
+
+1. A confirmation is displayed, including information about where your files are stored.
+
+A public and private key are generated.
+[Add the public SSH key to your GitLab account](#add-an-ssh-key-to-your-gitlab-account).
+
+## Add an SSH key to your GitLab account
+
+To use SSH with GitLab, copy your public key to your GitLab account.
+
+1. Copy the contents of your public key file. You can do this manually or use a script.
+   For example, to copy an ED25519 key to the clipboard:
+
+   **macOS:**
+
+   ```shell
+   tr -d '\n' < ~/.ssh/id_ed25519.pub | pbcopy
+   ```
+
+   **Linux** (requires the `xclip` package):
+
+   ```shell
+   xclip -sel clip < ~/.ssh/id_ed25519.pub
+   ```
+
+   **Git Bash on Windows:**
+
+   ```shell
+   cat ~/.ssh/id_ed25519.pub | clip
+   ```
+
+   Replace `id_ed25519.pub` with your filename. For example, use `id_rsa.pub` for RSA.
+
+1. Sign in to GitLab.
+1. On the top bar, in the top right corner, select your avatar.
+1. Select **Preferences**.
+1. On the left sidebar, select **SSH Keys**.
+1. In the **Key** box, paste the contents of your public key.
+   If you manually copied the key, make sure you copy the entire key,
+   which starts with `ssh-rsa`, `ssh-dss`, `ecdsa-sha2-nistp256`, `ecdsa-sha2-nistp384`, `ecdsa-sha2-nistp521`,
+   `ssh-ed25519`, `sk-ecdsa-sha2-nistp256@openssh.com`, or `sk-ssh-ed25519@openssh.com`, and may end with a comment.
+1. In the **Title** box, type a description, like `Work Laptop` or
+   `Home Workstation`.
+1. Optional. In the **Expires at** box, select an expiration date. ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/36243) in GitLab 12.9.)
+   In:
+   - GitLab 13.12 and earlier, the expiration date is informational only. It doesn't prevent
+     you from using the key. Administrators can view expiration dates and use them for
+     guidance when [deleting keys](admin_area/credentials_inventory.md#delete-a-users-ssh-key).
+   - GitLab 14.0 and later, the expiration date is enforced. Administrators can
+     [allow expired keys to be used](admin_area/settings/account_and_limit_settings.md#allow-expired-ssh-keys-to-be-used-deprecated).
+   - GitLab checks all SSH keys at 02:00 AM UTC every day. It emails an expiration notice for all SSH keys that expire on the current date. ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/322637) in GitLab 13.11.)
+   - GitLab checks all SSH keys at 01:00 AM UTC every day. It emails an expiration notice for all SSH keys that are scheduled to expire seven days from now. ([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/322637) in GitLab 13.11.)
+1. Select **Add key**.
+
+## Verify that you can connect
+
+Verify that your SSH key was added correctly.
+
+1. For GitLab.com, to ensure you're connecting to the correct server, confirm the
+   [SSH host keys fingerprints](gitlab_com/index.md#ssh-host-keys-fingerprints).
+1. Open a terminal and run this command, replacing `gitlab.example.com` with your GitLab instance URL:
+
+   ```shell
+   ssh -T git@gitlab.example.com
+   ```
+
+1. If this is the first time you connect, you should verify the
+   authenticity of the GitLab host. If you see a message like:
+
+   ```plaintext
+   The authenticity of host 'gitlab.example.com (35.231.145.151)' can't be established.
+   ECDSA key fingerprint is SHA256:HbW3g8zUjNSksFbqTiUWPWg2Bq1x8xdGUrliXFzSnUw.
+   Are you sure you want to continue connecting (yes/no)? yes
+   Warning: Permanently added 'gitlab.example.com' (ECDSA) to the list of known hosts.
+   ```
+
+   Type `yes` and press Enter.
+
+1. Run the `ssh -T git@gitlab.example.com` command again. You should receive a _Welcome to GitLab, `@username`!_ message.
+
+If the welcome message doesn't appear, you can troubleshoot by running `ssh`
+in verbose mode:
+
+```shell
+ssh -Tvvv git@gitlab.example.com
+```
+
+## Use different keys for different repositories
+
+You can use a different key for each repository.
+
+Open a terminal and run this command:
+
+```shell
+git config core.sshCommand "ssh -o IdentitiesOnly=yes -i ~/.ssh/private-key-filename-for-this-repository -F /dev/null"
+```
+
+This command does not use the SSH Agent and requires Git 2.10 or later. For more information
+on `ssh` command options, see the `man` pages for both `ssh` and `ssh_config`.
+
+## Use different accounts on a single GitLab instance
+
+You can use multiple accounts to connect to a single instance of GitLab.
+You can do this by using the command in the [previous topic](#use-different-keys-for-different-repositories).
+However, even if you set `IdentitiesOnly` to `yes`, you cannot sign in if an `IdentityFile` exists
+outside of a `Host` block.
+
+Instead, you can assign aliases to hosts in the `~.ssh/config` file.
+
+- For the `Host`, use an alias like `user_1.gitlab.com` and
+  `user_2.gitlab.com`. Advanced configurations
+  are more difficult to maintain, and these strings are easier to
+  understand when you use tools like `git remote`.
+- For the `IdentityFile`, use the path the private key.
+
+```conf
+# User1 Account Identity
+Host <user_1.gitlab.com>
+  Hostname gitlab.com
+  PreferredAuthentications publickey
+  IdentityFile ~/.ssh/<example_ssh_key1>
+
+# User2 Account Identity
+Host <user_2.gitlab.com>
+  Hostname gitlab.com
+  PreferredAuthentications publickey
+  IdentityFile ~/.ssh/<example_ssh_key2>
+```
+
+Now, to clone a repository for `user_1`, use `user_1.gitlab.com` in the `git clone` command:
+
+```shell
+git clone git@<user_1.gitlab.com>:gitlab-org/gitlab.git
+```
+
+To update a previously-cloned repository that is aliased as `origin`:
+
+```shell
+git remote set-url origin git@<user_1.gitlab.com>:gitlab-org/gitlab.git
+```
+
+NOTE:
+Private and public keys contain sensitive data. Ensure the permissions
+on the files make them readable to you but not accessible to others.
+
+## Configure two-factor authentication (2FA)
+
+You can set up two-factor authentication (2FA) for
+[Git over SSH](../security/two_factor_authentication.md#2fa-for-git-over-ssh-operations). We recommend using
+[ED25519_SK](#ed25519_sk-ssh-keys) or [ECDSA_SK](#ecdsa_sk-ssh-keys) SSH keys.
+
+## Use EGit on Eclipse
+
+If you are using [EGit](https://www.eclipse.org/egit/), you can [add your SSH key to Eclipse](https://wiki.eclipse.org/EGit/User_Guide#Eclipse_SSH_Configuration).
+
+## Use SSH on Microsoft Windows
+
+If you're running Windows 10, you can either use the [Windows Subsystem for Linux (WSL)](https://docs.microsoft.com/en-us/windows/wsl/install)
+with [WSL 2](https://docs.microsoft.com/en-us/windows/wsl/install#update-to-wsl-2) which
+has both `git` and `ssh` preinstalled, or install [Git for Windows](https://gitforwindows.org) to
+use SSH through PowerShell.
+
+The SSH key generated in WSL is not directly available for Git for Windows, and vice versa,
+as both have a different home directory:
+
+- WSL: `/home/<user>`
+- Git for Windows: `C:\Users\<user>`
+
+You can either copy over the `.ssh/` directory to use the same key, or generate a key in each environment.
+
+Alternative tools include:
+
+- [Cygwin](https://www.cygwin.com)
+- [PuttyGen](https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html)
+
+## Overriding SSH settings on the GitLab server
+
+GitLab integrates with the system-installed SSH daemon and designates a user
+(typically named `git`) through which all access requests are handled. Users
+who connect to the GitLab server over SSH are identified by their SSH key instead
+of their username.
+
+SSH *client* operations performed on the GitLab server are executed as this
+user. You can modify this SSH configuration. For example, you can specify
+a private SSH key for this user to use for authentication requests. However, this practice
+is **not supported** and is strongly discouraged as it presents significant
+security risks.
+
+GitLab checks for this condition, and directs you
+to this section if your server is configured this way. For example:
+
+```shell
+$ gitlab-rake gitlab:check
+
+Git user has default SSH configuration? ... no
+  Try fixing it:
+  mkdir ~/gitlab-check-backup-1504540051
+  sudo mv /var/lib/git/.ssh/id_rsa ~/gitlab-check-backup-1504540051
+  sudo mv /var/lib/git/.ssh/id_rsa.pub ~/gitlab-check-backup-1504540051
+  For more information see:
+  doc/user/ssh.md#overriding-ssh-settings-on-the-gitlab-server
+  Please fix the error above and rerun the checks.
+```
+
+Remove the custom configuration as soon as you can. These customizations
+are **explicitly not supported** and may stop working at any time.
+
+## Troubleshooting
+
+### Password prompt with `git clone`
+
+When you run `git clone`, you may be prompted for a password, like `git@gitlab.example.com's password:`.
+This indicates that something is wrong with your SSH setup.
+
+- Ensure that you generated your SSH key pair correctly and added the public SSH
+  key to your GitLab profile.
+- Try to manually register your private SSH key by using `ssh-agent`.
+- Try to debug the connection by running `ssh -Tv git@example.com`.
+  Replace `example.com` with your GitLab URL.
+
+### `Could not resolve hostname` error
+
+You may receive the following error when [verifying that you can connect](#verify-that-you-can-connect):
+
+```shell
+ssh: Could not resolve hostname gitlab.example.com: nodename nor servname provided, or not known
+```
+
+If you receive this error, restart your terminal and try the command again.
+
+### `Key enrollment failed: invalid format` error
+
+You may receive the following error when [generating an SSH key pair for a FIDO/U2F hardware security key](#generate-an-ssh-key-pair-for-a-fidou2f-hardware-security-key):
+
+```shell
+Key enrollment failed: invalid format
+```
+
+You can troubleshoot this by trying the following:
+
+- Run the `ssh-keygen` command using `sudo`.
+- Verify your IDO/U2F hardware security key supports
+  the key type provided.
+- Verify the version of OpenSSH is 8.2 or greater by
+  running `ssh -v`.

lib/system_check/app/git_user_default_ssh_config_check.rb

@@ -31,7 +31,7 @@ module SystemCheck
         end
 
         try_fixing_it("mkdir #{backup_dir}", *instructions)
-        for_more_information('doc/ssh/index.md in section "Overriding SSH settings on the GitLab server"')
+        for_more_information('doc/user/ssh.md#overriding-ssh-settings-on-the-gitlab-server')
         fix_and_rerun
       end
 

spec/lib/system_check/app/git_user_default_ssh_config_check_spec.rb

@@ -71,7 +71,31 @@ RSpec.describe SystemCheck::App::GitUserDefaultSSHConfigCheck do
     end
   end
 
+  describe '#show_error' do
+    subject(:show_error) { described_class.new.show_error }
+
+    before do
+      stub_user
+      stub_home_dir
+      stub_ssh_file(forbidden_file)
+    end
+
+    it 'outputs error information' do
+      expected = %r{
+        Try\ fixing\ it:\s+
+        mkdir\ ~/gitlab-check-backup-(.+)\s+
+        sudo\ mv\ (.+)\s+
+        For\ more\ information\ see:\s+
+        doc/user/ssh\.md\#overriding-ssh-settings-on-the-gitlab-server\s+
+        Please\ fix\ the\ error\ above\ and\ rerun\ the\ checks
+      }x
+
+      expect { show_error }.to output(expected).to_stdout
+    end
+  end
+
   def stub_user
+    allow(File).to receive(:expand_path).and_call_original
     allow(File).to receive(:expand_path).with("~#{username}").and_return(home_dir)
   end