Generate Ssh Key For Specific User

15.04.2020by
  1. Generate Ssh Key For User Linux
  2. Generate Ssh Key For Github
  3. Generate Ssh Key For Jenkins User Windows
  • Manage user accounts and user attributes.
  • For Windows targets, use the win_user module instead.
ParameterChoices/DefaultsComments
append
boolean
    Choices:
  • yes
If yes, add the user to the groups specified in groups.
If no, user will only be added to the groups specified in groups, removing them from all other groups.
authorization
added in 2.8
Does nothing when used with other platforms.
Can set multiple authorizations using comma separation.
To delete all authorizations, use authorization='.
comment
Optionally sets the description (aka GECOS) of user account.
create_home
boolean
    Choices:
  • no
Unless set to no, a home directory will be made for the user when the account is created or if the home directory does not exist.
Changed from createhome to create_home in Ansible 2.5.
expires
An expiry time for the user in epoch, it will be ignored on platforms that do not support this.
Currently supported on GNU/Linux, FreeBSD, and DragonFlyBSD.
Since Ansible 2.6 you can remove the expiry time specify a negative value. Currently supported on GNU/Linux and FreeBSD.
force
boolean
    Choices:
  • yes
This only affects state=absent, it forces removal of the user and associated directories on supported platforms.
The behavior is the same as userdel --force, check the man page for userdel on your system for details and support.
When used with generate_ssh_key=yes this forces an existing key to be overwritten.
generate_ssh_key
boolean
    Choices:
  • yes
Whether to generate a SSH key for the user in question.
This will not overwrite an existing SSH key unless used with force=yes.
group
string
Optionally sets the user's primary group (takes a group name).
groups
list
List of groups user will be added to. When set to an empty string ', the user is removed from all groups except the primary group.
Before Ansible 2.3, the only input format allowed was a comma separated string.
hidden
added in 2.6
    Choices:
  • no
  • yes
macOS only, optionally hide the user from the login window and system preferences.
The default will be yes if the system option is used.
home
path
local
added in 2.4
    Choices:
  • yes
Forces the use of 'local' command alternatives on platforms that implement it.
This is useful in environments that use centralized authentification when you want to manipulate the local users (i.e. it uses luseradd instead of useradd).
This will check /etc/passwd for an existing account before invoking commands. If the local account database exists somewhere other than /etc/passwd, this setting will not work properly.
This requires that the above commands as well as /etc/passwd must exist on the target host, otherwise it will be a fatal error.
login_class
Optionally sets the user's login class, a feature of most BSD OSs.
move_home
boolean
    Choices:
  • yes
If set to yes when used with home: , attempt to move the user's old home directory to the specified directory if it isn't there already and the old home exists.
name
string / required

aliases: user
non_unique
boolean
    Choices:
  • yes
Optionally when used with the -u option, this option allows to change the user ID to a non-unique value.
password
string
Optionally set the user's password to this crypted value.
On macOS systems, this value has to be cleartext. Beware of security issues.
To create a disabled account on Linux systems, set this to '!' or '*'.
To create a disabled account on OpenBSD, set this to '*************'.
See https://docs.ansible.com/ansible/faq.html#how-do-i-generate-encrypted-passwords-for-the-user-module for details on various ways to generate these password values.
password_lock
boolean
    Choices:
  • no
  • yes
Lock the password (usermod -L, pw lock, usermod -C).
BUT implementation differs on different platforms, this option does not always mean the user cannot login via other methods.
This option does not disable the user, only lock the password. Do not change the password in the same task.
Currently supported on Linux, FreeBSD, DragonFlyBSD, NetBSD, OpenBSD.
profile
string
Sets the profile of the user.
Can set multiple profiles using comma separation.
Currently supported on Illumos/Solaris.
remove
boolean
    Choices:
  • yes
This only affects state=absent, it attempts to remove directories associated with the user.
The behavior is the same as userdel --remove, check the man page for details and support.
role
string
Sets the role of the user.
Can set multiple roles using comma separation.
Currently supported on Illumos/Solaris.
seuser
string
Optionally sets the seuser type (user_u) on selinux enabled systems.
shell
string
On macOS, before Ansible 2.5, the default shell for non-system users was /usr/bin/false. Since Ansible 2.5, the default shell for non-system users on macOS is /bin/bash.
On other operating systems, the default shell is determined by the underlying tool being used. See Notes for details.
skeleton
string
Requires create_home option!
ssh_key_bits
integer
Default:
Optionally specify number of bits in SSH key to create.
ssh_key_comment
string
Default:
Optionally define the comment for the SSH key.
ssh_key_file
path
If this is a relative filename then it will be relative to the user's home directory.
ssh_key_passphrase
Set a passphrase for the SSH key.
If no passphrase is provided, the SSH key will default to having no passphrase.
ssh_key_type
string
Default:
Optionally specify the type of SSH key to generate.
Available SSH key types will depend on implementation present on target host.
state
string
    Choices:
  • absent
Whether the account should exist or not, taking action if the state is different from what is stated.
system
boolean
    Choices:
  • yes
When creating an account state=present, setting this to yes makes the user a system account.
uid
Optionally sets the UID of the user.
update_password
string
    Choices:
  • on_create
always will update passwords if they differ.
on_create will only set the password for newly created users.

  • In order to generate a SSH key on Debian, you are going to need the ssh-keygen tool. By default, ssh-keygen is already installed on Debian 10. To create a SSH key pair, use the following command. $ ssh-keygen -t rsa -b 4096 -C ' email protected '.
  • If you generate the key for the user you also have to have a secure method of getting the private key and it's pass phrase to the user. Much better the user generate the key and then just email you the public key. – user9517 Oct 22 '11 at 20:02.
  • Simply used ssh-copy-id to send your public key to the remote host. In the case of the ubuntu user, you will need a copy of the private key and use ssh-copy-id ubuntu@aws which will copy your default ssh public key to the ubuntu user's /.ssh/authorizedkeys file.
  • Jun 26, 2019  To set up SSH key authentication for one of your server’s users, add your public key to a new line inside the user’s authorizedkeys file. This file is stored inside a directory named.ssh/ under the user’s home folder. A user’s authorizedkeys file can store more than one public key, and each public key is listed on its own line.
  • Apr 02, 2019  Linux Basics: How To Create and Install SSH Keys on the Shell. On this page. Generating a key pair offers users two lengthy strings of characters corresponding to a public as well as a private key. Users can, thus, place the public key on any server, and subsequently, unlock the same by connecting to it with a client that already possesses.
  • Nov 10, 2011 How to Generate A Public/Private SSH Key Linux By Damien – Posted on Nov 10, 2011 Nov 18, 2011 in Linux If you are using SSH frequently to connect to a remote host, one of the way to secure the connection is to use a public/private SSH key so no password is transmitted over the network and it can prevent against brute force attack.

Note

Mar 31, 2020  If you need to add users who don't have SSH keys, generate a new SSH key for each new user. If you need to add users who have existing SSH keys, locate the public SSH key file for each user. Format any public SSH keys that you want to add so they work correctly with the tool that you use to edit metadata. Optionally, you can also format your.

  • There are specific requirements per platform on user management utilities. However they generally come pre-installed with the system and Ansible will require they are present at runtime. If they are not, a descriptive error message will be shown.
  • On SunOS platforms, the shadow file is backed up automatically since this module edits it directly. On other platforms, the shadow file is backed up by the underlying tools used by this module.
  • On macOS, this module uses dscl to create, modify, and delete accounts. dseditgroup is used to modify group membership. Accounts are hidden from the login window by modifying /Library/Preferences/com.apple.loginwindow.plist.
  • On FreeBSD, this module uses pwuseradd and chpass to create, pwusermod and chpass to modify, pwuserdel remove, pwlock to lock, and pwunlock to unlock accounts.
  • On all other platforms, this module uses useradd to create, usermod to modify, and userdel to remove accounts.

See also

authorized_key – Adds or removes an SSH authorized key
The official documentation on the authorized_key module.
group – Add or remove groups
The official documentation on the group module.
win_user – Manages local Windows user accounts
The official documentation on the win_user module.

Common return values are documented here, the following are the fields unique to this module:

KeyReturnedDescription
append
boolean
When state is 'present' and the user exists
Sample:
commentWhen user exists
Comment section from passwd file, usually the user name

Agent Smith
create_home
boolean
When user does not exist and not check mode
Sample:
forceWhen state is 'absent' and user exists
Whether or not a user account was forcibly deleted

group
integer
When user exists
Sample:
groupsWhen groups is not empty and state is 'present'
List of groups of which the user is a member

chrony,apache
home
string
When state is 'present'
Sample:
move_homeWhen state is 'present' and user exists
Whether or not to move an existing home directory

name
string
always
Sample:
passwordWhen state is 'present' and password is not empty
Masked value of the password

NOT_LOGGING_PASSWORD
remove
boolean
When state is 'absent' and user exists
Sample:
shellWhen state is 'present'
User login shell

/bin/bash
ssh_fingerprint
string
When generate_ssh_key is True
Sample:
2048 SHA256:aYNHYcyVm87Igh0IMEDMbvW0QDlRQfE0aJugp684ko8 ansible-generated on host (RSA)
ssh_key_file
string
When generate_ssh_key is True
Sample:
ssh_public_keyWhen generate_ssh_key is True
Generated SSH public key file

'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC95opt4SPEC06tOYsJQJIuN23BbLMGmYo8ysVZQc4h2DZE9ugbjWWGS1/pweUGjVstgzMkBEeBCByaEf/RJKNecKRPeGd2Bw9DCj/bn5Z6rGfNENKBmo 618mUJBvdlEgea96QGjOwSB7/gmonduC7gsWDMNcOdSE3wJMTim4lddiBx4RgC9yXsJ6Tkz9BHD73MXPpT5ETnse+A3fw3IGVSjaueVnlUyUmOBf7fzmZbhlFVXf2Zi2rFTXqvbdGHKkzpw1U8eB8xFPP7y d5u1u0e6Acju/8aZ/l17IDFiLke5IzlqIMRTEbDwLNeO84YQKWTm9fODHzhYe0yvxqLiK07 ansible-generated on host'
stderr
string
When stderr is returned by a command that is run
Sample:
stdoutWhen standard output is returned by the command that is run
Standard output from running commands

system
boolean
When system is passed to the module and the account does not exist
Sample:
uidWhen UID is passed to the module
User ID of the user account

1044

  • This module is guaranteed to have backward compatible interface changes going forward. [stableinterface]
  • This module is maintained by the Ansible Core Team. [core]

Red Hat Support¶

More information about Red Hat’s support of this module is available from this Red Hat Knowledge Base article.

Authors¶

  • Stephen Fromm (@sfromm)

Hint

If you notice any issues in this documentation, you can edit this document to improve it.

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Password authentication is the default method most SSH (Secure Shell) clients use to authenticate with remote servers, but it suffers from potential security vulnerabilities, like brute-force login attempts. An alternative to password authentication is public key authentication, in which you generate and store on your computer a pair of cryptographic keys and then configure your server to recognize and accept your keys. Using key-based authentication offers a range of benefits:

  • Key-based login is not a major target for brute-force hacking attacks.

  • If a server that uses SSH keys is compromised by a hacker, no authorization credentials are at risk of being exposed.

  • Because a password isn’t required at login, you are able to able to log in to servers from within scripts or automation tools that you need to run unattended. For example, you can set up periodic updates for your servers with a configuration management tool like Ansible, and you can run those updates without having to be physically present.

This guide will explain how the SSH key login scheme works, how to generate an SSH key, and how to use those keys with your Linode.

Note
If you’re unfamiliar with SSH connections, review the Getting Started with Linode guide.

How SSH Keys Work

SSH keys are generated in pairs and stored in plain-text files. The key pair (or keypair) consists of two parts:

  • A private key, usually named id_rsa. The private key is stored on your local computer and should be kept secure, with permissions set so that no other users on your computer can read the file.

    Caution
  • A public key, usually named id_rsa.pub. The public key is placed on the server you intend to log in to. You can freely share your public key with others. If someone else adds your public key to their server, you will be able to log in to that server.

When a site or service asks for your SSH key, they are referring to your SSH public key (id_rsa.pub). For instance, services like GitHub and Gitlab allow you to place your SSH public key on their servers to streamline the process of pushing code changes to remote repositories.

The authorized_keys File

In order for your Linode to recognize and accept your key pair, you will need to upload your public key to your server. More specifically, you will need to upload your public key to the home directory of the user you would like to log in as. If you would like to log in to more than one user on the server using your key pair, you will need to add your public key to each of those users.

To set up SSH key authentication for one of your server’s users, add your public key to a new line inside the user’s authorized_keys file. This file is stored inside a directory named .ssh/ under the user’s home folder. A user’s authorized_keys file can store more than one public key, and each public key is listed on its own line. If your file contains more than one public key, then the owner of each key listed will be able to log in as that user.

Granting Someone Else Access to your Server

To give someone else access to your server’s user, simply add their public key on a new line in your authorized_keys file, just as you would add your own. To revoke access for that person, remove that same line and save the changes.

Challenge-Response

When logging in to a server using SSH, if there is a public key on file on that server, the server will create a challenge. This challenge will be crafted in such a way that only the holder of the private SSH key will be able to decipher it.

This challenge-response action happens without any user interaction. If the person attempting to log in has the corresponding private key, then they will be safely logged in. If not, the login will either fail or fall back to a password-based authentication scheme.

Generate Ssh Key For Specific User

SSH Key Passphrases

You can optionally provide an additional level of security for your SSH keys by encrypting them with a passphrase at the time of creation. When you attempt to log in using an encrypted SSH key, you will be prompted to enter its passphrase. This is not to be confused with a password, as this passphrase only decrypts the key file locally and is not transferred over the Internet as a password might be.

If you’d like to set up your logins so that they require no user input, then creating a passphrase might not be desirable, but it is strongly recommended nevertheless.

Linux and macOS

Generate a Key Pair

Perform the steps in this section on your local machine.

  1. Create a new key pair.

    Caution

    This command will overwrite an existing RSA key pair, potentially locking you out of other systems.

    If you’ve already created a key pair, skip this step. To check for existing keys, run ls ~/.ssh/id_rsa*.

    If you accidentally lock yourself out of the SSH service on your Linode, you can still use the Lish console to login to your server. After you’ve logged in via Lish, update your authorized_keys file to use your new public key. This should re-establish normal SSH access.

    The -b flag instructs ssh-keygen to increase the number of bits used to generate the key pair, and is suggested for additional security.

  2. Press Enter to use the default names id_rsa and id_rsa.pub in the /home/your_username/.ssh directory before entering your passphrase.

  3. While creating the key pair, you will be given the option to encrypt the private key with a passphrase. This means that the key pair cannot be used without entering the passphrase (unless you save that passphrase to your local machine’s keychain manager). We suggest that you use the key pair with a passphrase, but you can leave this field blank if you don’t want to use one.

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Upload your Public Key

There are a few different ways to upload your public key to your Linode from Linux and macOS client systems:

Using ssh-copy-id

ssh-copy-id is a utility available on some operating systems that can copy a SSH public key to a remote server over SSH.

  1. To use ssh-copy-id, pass your username and the IP address of the server you would like to access:

  2. You’ll see output like the following, and a prompt to enter your user’s password:

  3. Verify that you can log in to the server with your key.

Using Secure Copy (scp)

Secure Copy (scp) is a tool that copies files from a local computer to a remote server over SSH:

Generate Ssh Key For User Linux

Caution
These instructions will overwrite any existing contents of the authorized_keys file on your server. If you have already set up other public keys on your server, use the ssh-copy-id command or enter your key manually.
  1. Connect to your server via SSH with the user you would like to add your key to:

  2. Create the ~/.ssh directory and authorized_keys file if they don’t already exist:

  3. Give the ~/.ssh directory and authorized_keys files appropriate file permissions:

  4. In another terminal on your local machine, use scp to copy the contents of your SSH public key (id_rsa.pub) into the authorized_keys file on your server. Substitute in your own username and your server’s IP address:

  5. Verify that you can log in to the server with your key.

Manually Copy an SSH Key

You can also manually add an SSH key to a server:

  1. Begin by copying the contents of your public SSH key on your local computer. You can use the following command to output the contents of the file:

    You should see output similar to the following:

    Note that the public key begins with ssh-rsa and ends with [email protected].

  2. Once you have copied that text, connect to your server via SSH with the user you would like to add your key to:

  3. Create the ~/.ssh directory and authorized_keys file if they don’t already exist:

  4. Give the ~/.ssh directory and authorized_keys files appropriate file permissions:

  5. Open the authorized_keys file with the text editor of your choice (nano, for example). Then, paste the contents of your public key that you copied in step one on a new line at the end of the file.

  6. Save and close the file.

    Note

    If you initially logged into the server as root but edited the authorized_keys file of another user, then the .ssh/ folder and authorized_keys file of that user may be owned by root. Set that other user as the files’ owner:

  7. Verify that you can log in to the server with your key.

Connect to the Remote Server

  1. SSH into the server from your local machine:

  2. If you chose to use a passphrase when creating your SSH key, you will be prompted to enter it when you attempt to log in. Depending on your desktop environment, a window may appear:

    Caution
    Do not allow the local machine to remember the passphrase in its keychain unless you are on a private computer which you trust.

    You may also see the passphrase prompt at your command line:

  3. Enter your password. You should see the connection establish in the local terminal.

Windows

The following instructions use the PuTTY software to connect over SSH, but other options are available on Windows too.

Generate a Key Pair with PuTTY

  1. Download PuTTYgen (puttygen.exe) and PuTTY (putty.exe) from the official site.

  2. Launch puttygen.exe. The RSA key type at the bottom of the window is selected by default for an RSA key pair but ED25519 (EdDSA using Curve25519) is a comparable option if your remote machine’s SSH server supports DSA signatures. Do not use the SSH-1(RSA) key type unless you know what you’re doing.

  3. Increase the RSA key size from 2048 bits 4096 and click Generate:

  4. PuTTY uses the random input from your mouse to generate a unique key. Once key generation begins, keep moving your mouse until the progress bar is filled:

  5. When finished, PuTTY will display the new public key. Right-click on it and select Select All, then copy the public key into a Notepad file.

  6. Save the public key as a .txt file or some other plaintext format. This is important–a rich text format such as .rtf or .doc can add extra formatting characters and then your private key won’t work:

  7. Enter a passphrase for the private key in the Key passphrase and Confirm passphrase text fields. Important: Make a note of your passphrase, you’ll need it later:

  8. Click Save private key. Choose a file name and location in Explorer while keeping the ppk file extension. If you plan to create multiple key pairs for different servers, be sure to give them different names so that you don’t overwrite old keys with new:

Manually Copy the SSH Key with PuTTY

  1. Launch putty.exe. Find the Connection tree in the Category window, expand SSH and select Auth. Click Browse and navigate to the private key you created above:

  2. Scroll back to the top of the Category window and click Session. Enter the hostname or IP address of your Linode. PuTTY’s default TCP port is 22, the IANA assigned port for for SSH traffic. Change it if your server is listening on a different port. Name the session in the Saved Sessions text bar and click Save:

  3. Click the Open button to establish a connection. You will be prompted to enter a login name and password for the remote server.

  4. Once you’re logged in to the remote server, configure it to authenticate with your SSH key pair instead of a user’s password. Create an .ssh directory in your home directory on your Linode, create a blank authorized_keys file inside, and set their access permissions:

  5. Open the authorized_keys file with the text editor of your choice (nano, for example). Then, paste the contents of your public key that you copied in step one on a new line at the end of the file.

  6. Save, close the file, and exit PuTTY.

  7. Verify that you can log in to the server with your key.

Using WinSCP

Uploading a public key from Windows can also be done using WinSCP:

Caution
These instructions will overwrite any existing contents of the authorized_keys file on your server. If you have already set up other public keys on your server, use the PuTTY instructions instead.
  1. In the login window, enter your Linode’s public IP address as the hostname, the user you would like to add your key to, and your user’s password. Click Login to connect.

  2. Once connected, WinSCP will show two file tree sections. The left shows files on your local computer and the right shows files on your Linode. Using the file explorer on the left, navigate to the file where you saved your public key in Windows. Select the public key file and click Upload in the toolbar above.

  3. You’ll be prompted to enter a path on your Linode where you want to upload the file. Upload the file to /home/your_username/.ssh/authorized_keys.

  4. Verify that you can log in to the server with your key.

Connect to the Remote Server with PuTTY

Start PuTTY and Load your saved session. You’ll be prompted to enter your server user’s login name as before. However, this time you will be prompted for your private SSH key’s passphrase rather than the password for your server’s user. Enter the passphrase and press Enter.

Troubleshooting

If your SSH connections are not working as expected, or if you have locked yourself out of your system, review the Troubleshooting SSH guide for troubleshooting help.

Upload your SSH Key to the Cloud Manager

It is possible to provision each new Linode you create with an SSH public key automatically through the Cloud Manager.

  1. Log in to the Cloud Manager.

  2. Click on your username at the top right hand side of the page. Then click on My Profile in the dropdown menu that appears:

    Note
    If you are viewing the Cloud Manager in a smaller browser window or on a smaller device, then the My Profile link will appear in the sidebar links. To view the sidebar links, click on the disclosure button to the left of the blue Create button at the top of the page.
  3. From the My Profile page, select the SSH Keys tab, and then click Add a SSH Key:

  4. Create a label for your key, then paste in the contents of your public SSH key (id_rsa.pub):

  5. Click Add Key.

  6. When you next create a Linode you’ll be given the opportunity to include your SSH key in the Linode’s creation. This key will be added to the root user of the new Linode.

    In the Create Linode form, select the SSH key you’d like to include. This field will appear below the Root Password field:

Next Steps

Generate Ssh Key For Github

After you set up your SSH keys and confirm they are working as expected, review the How to Secure Your Server guide for instructions on disabling password authentication for your server.

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Generate Ssh Key For Jenkins User Windows

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