• Git Linux Generate Ssh Key Windows 10
• Generate Ssh Key Linux Github
• Ssh Generate Key
• Generate Ssh Key Putty

Azure Repos Azure DevOps Server 2019 TFS 2018 TFS 2017 TFS 2015 Update 3

Connect to your Git repos through SSH on macOS, Linux, or Windows to securely connect using HTTPS authentication. On Windows, we recommended the use of Git Credential Managers or Personal Access Tokens.

Create your SSH keys with the ssh-keygen command from the bash prompt. This command will create a 2048-bit RSA key for use with SSH. This command will create a 2048-bit RSA key for use with SSH. You can give a passphrase for your private key when prompted—this passphrase provides another layer of security for your private key.

• To create a new key pair, select the type of key to generate from the bottom of the screen (using SSH-2 RSA with 2048 bit key size is good for most people; another good well-known alternative is ECDSA).
• Generate the SSH key with ssh-keygen -t rsa -b 4096 (see here) Copy the content of your public SSH key, it is the file idrsa.pub by default Paste the content into your GitHub/BitBucket account on the SSH key section.
• In order to add a SSH key to your GitHub account, head over to the settings of your account and select the “SSH and GPG keys” option in the left menu. On the right panel, click on the “ New SSH key ” button in order to create a new SSH key for Github.

Important

SSH URLs have changed, but old SSH URLs will continue to work. If you have already set up SSH, you should update your remote URLs to the new format:

• Verify which remotes are using SSH by running git remote -v in your Git client.
• Visit your repository on the web and select the Clone button in the upper right.
• Select SSH and copy the new SSH URL.
• In your Git client, run: git remote set-url <remote name, e.g. origin> <new SSH URL>. Alternatively, in Visual Studio, go to Repository Settings, and edit your remotes.

Note

As of Visual Studio 2017, SSH can be used to connect to Git repos.

How SSH key authentication works

SSH public key authentication works with an asymmetric pair of generated encryption keys. The public key is shared with Azure DevOps and used to verify the initial ssh connection. The private key is kept safe and secure on your system.

Set up SSH key authentication

The following steps cover configuration of SSH key authentication on the following platforms:

• Linux
• macOS running at least Leopard (10.5)
• Windows systems running Git for Windows

Configure SSH using the command line. bash is the common shell on Linux and macOS and the Git for Windows installation adds a shortcut to Git Bash in the Start menu.Other shell environments will work, but are not covered in this article.

Step 1: Create your SSH keys

Note

If you have already created SSH keys on your system, skip this step and go to configuring SSH keys.

The commands here will let you create new default SSH keys, overwriting existing default keys. Before continuing, check your~/.ssh folder (for example, /home/jamal/.ssh or C:Usersjamal.ssh) and look for the following files:

• id_rsa
• id_rsa.pub

If these files exist, then you have already created SSH keys. You can overwrite the keys with the following commands, or skip this step and go to configuring SSH keys to reuse these keys.

Create your SSH keys with the ssh-keygen command from the bash prompt. This command will create a 2048-bit RSA key for use with SSH. You can give a passphrasefor your private key when prompted—this passphrase provides another layer of security for your private key.If you give a passphrase, be sure to configure the SSH agent to cache your passphrase so you don't have to enter it every time you connect.

This command produces the two keys needed for SSH authentication: your private key ( id_rsa ) and the public key ( id_rsa.pub ). It is important to never share the contents of your private key. If the private key iscompromised, attackers can use it to trick servers into thinking the connection is coming from you.

Step 2: Add the public key to Azure DevOps Services/TFS

Associate the public key generated in the previous step with your user ID.

1. Open your security settings by browsing to the web portal and selecting your avatar in the upper right of theuser interface. Select Security in the menu that appears.

2. Select SSH public keys, and then select + New Key.

3. Copy the contents of the public key (for example, id_rsa.pub) that you generated into the Public Key Data field.

   Important

   Avoid adding whitespace or new lines into the Key Data field, as they can cause Azure DevOps Services to use an invalid public key. When pasting in the key, a newline often is added at the end. Be sure to remove this newline if it occurs.

4. Give the key a useful description (this description will be displayed on the SSH public keys page for your profile) so that you can remember it later. Select Save to store the public key. Once saved, you cannot change the key. You can delete the key or create a new entry for another key. There are no restrictions on how many keys you can add to your user profile.

Step 3: Clone the Git repository with SSH

Note

To connect with SSH from an existing cloned repo, see updating your remotes to SSH.

1. Copy the SSH clone URL from the web portal. In this example, the SSL clone URL is for a repo in an organization named fabrikam-fiber, as indicated by the first part of the URL after dev.azure.com.

   Note

   Project URLs have changed with the release of Azure DevOps Services and now have the format dev.azure.com/{your organization}/{your project}, but you can still use the existing visualstudio.com format. For more information, see VSTS is now Azure DevOps Services.

2. Run git clone from the command prompt.

SSH may display the server's SSH fingerprint and ask you to verify it.

For cloud-hosted Azure DevOps Services, where clone URLs contain either ssh.dev.azure.com or vs-ssh.visualstudio.com, the fingerprint should match one of the following formats:

• MD5: 97:70:33:82:fd:29:3a:73:39:af:6a:07:ad:f8:80:49 (RSA)
• SHA256: SHA256:ohD8VZEXGWo6Ez8GSEJQ9WpafgLFsOfLOtGGQCQo6Og (RSA)These fingerprints are also listed in the SSH public keys page.

For self-hosted instances of Azure DevOps Server, you should verify that the displayed fingerprint matches one of the fingerprints in the SSH public keys page.

SSH displays this fingerprint when it connects to an unknown host to protect you from man-in-the-middle attacks.Once you accept the host's fingerprint, SSH will not prompt you again unless the fingerprint changes.

When you are asked if you want to continue connecting, type yes. Git will clone the repo and set up the origin remote to connect with SSH for future Git commands.

Tip

Avoid trouble: Windows users will need to run a command to have Git reuse their SSH key passphrase.

Questions and troubleshooting

Q: After running git clone, I get the following error. What should I do?

Host key verification failed.fatal: Could not read from remote repository.

A: Manually record the SSH key by running:ssh-keyscan -t rsa domain.com >> ~/.ssh/known_hosts

Q: How can I have Git remember the passphrase for my key on Windows?

A: Run the following command included in Git for Windows to start up the ssh-agent process in Powershell or the Windows Command Prompt. ssh-agent will cacheyour passphrase so you don't have to provide it every time you connect to your repo.

If you're using the Bash shell (including Git Bash), start ssh-agent with:

Q: I use PuTTY as my SSH client and generated my keys with PuTTYgen. Can I use these keys with Azure DevOps Services?

A: Yes. Load the private key with PuTTYgen, go to Conversions menu and select Export OpenSSH key.Save the private key file and then follow the steps to set up non-default keys.Copy your public key directly from the PuTTYgen window and paste into the Key Data field in your security settings.

Q: How can I verify that the public key I uploaded is the same key as I have locally?

A: You can verify the fingerprint of the public key uploaded with the one displayed in your profile through the following ssh-keygen command run against your public key usingthe bash command line. You will need to change the path and the public key filename if you are not using the defaults.

You can then compare the MD5 signature to the one in your profile. This check is useful if you have connection problems or have concerns about incorrectlypasting in the public key into the Key Data field when adding the key to Azure DevOps Services.

Q: How can I start using SSH in a repository where I am currently using HTTPS?

A: You'll need to update the origin remote in Git to change over from a HTTPS to SSH URL. Once you have the SSH clone URL, run the following command:

You can now run any Git command that connects to origin.

Q: I'm using Git LFS with Azure DevOps Services and I get errors when pulling files tracked by Git LFS.

A: Azure DevOps Services currently doesn't support LFS over SSH. Use HTTPS to connect to repos with Git LFS tracked files.

Q: How can I use a non default key location, i.e. not ~/.ssh/id_rsa and ~/.ssh/id_rsa.pub?

A: To use keys created with ssh-keygen in a different place than the default, you do two things:

1. The keys must be in a folder that only you can read or edit. If the folder has wider permissions, SSH will not use the keys.
2. You must let SSH know the location of the keys. You make SSH aware of keys through the ssh-add command, providing the full path to the private key.

On Windows, before running ssh-add, you will need to run the following command from included in Git for Windows:

This command runs in both Powershell and the Command Prompt. If you are using Git Bash, the command you need to use is:

You can find ssh-add as part of the Git for Windows distribution and also run it in any shell environment on Windows.

On macOS and Linux you also must have ssh-agent running before running ssh-add, but the command environment on these platforms usuallytakes care of starting ssh-agent for you.

Q: I have multiple SSH keys. How do I use different SSH keys for different SSH servers or repos?

A: Generally, if you configure multiple keys for an SSH client and connect to an SSH server, the client can try the keys one at a time until the server accepts one.

However, this doesn't work with Azure DevOps for technical reasons related to the SSH protocol and how our Git SSH URLs are structured. Azure DevOps will blindly accept the first key that the client provides during authentication. If that key is invalid for the requested repo, the request will fail with the following error:

For Azure DevOps, you'll need to configure SSH to explicitly use a specific key file. One way to do this to edit your ~/.ssh/config file (for example, /home/jamal/.ssh or C:Usersjamal.ssh) as follows:

Q: What notifications may I receive about my SSH keys?

A: Whenever you register a new SSH Key with Azure DevOps Services, you will receive an email notification informing you that a new SSH key has been added to your account.

Q: What do I do if I believe that someone other than me is adding SSH keys on my account?

A: If you receive a notification of an SSH key being registered and you did not manually upload it to the service, your credentials may have been compromised.

The next step would be to investigate whether or not your password has been compromised. Changing your password is always a good first step to defend against this attack vector. If you’re an Azure Active Directory user, talk with your administrator to check if your account was used from an unknown source/location.

This article or section needs expansion.

SSH keys can serve as a means of identifying yourself to an SSH server using public-key cryptography and challenge-response authentication. The major advantage of key-based authentication is that in contrast to password authentication it is not prone to brute-force attacks and you do not expose valid credentials, if the server has been compromised.[1]

Furthermore SSH key authentication can be more convenient than the more traditional password authentication. When used with a program known as an SSH agent, SSH keys can allow you to connect to a server, or multiple servers, without having to remember or enter your password for each system.

Key-based authentication is not without its drawbacks and may not be appropriate for all environments, but in many circumstances it can offer some strong advantages. A general understanding of how SSH keys work will help you decide how and when to use them to meet your needs.

This article assumes you already have a basic understanding of the Secure Shell protocol and have installed the openssh package.

• 2Generating an SSH key pair
  • 2.1Choosing the authentication key type
  • 2.2Choosing the key location and passphrase
• 3Copying the public key to the remote server
• 4SSH agents
  • 4.1ssh-agent
  • 4.3Keychain
  • 4.4x11-ssh-askpass
  • 4.5pam_ssh
• 5Troubleshooting

Background

SSH keys are always generated in pairs with one known as the private key and the other as the public key. The private key is known only to you and it should be safely guarded. By contrast, the public key can be shared freely with any SSH server to which you wish to connect.

If an SSH server has your public key on file and sees you requesting a connection, it uses your public key to construct and send you a challenge. This challenge is an encrypted message and it must be met with the appropriate response before the server will grant you access. What makes this coded message particularly secure is that it can only be understood by the private key holder. While the public key can be used to encrypt the message, it cannot be used to decrypt that very same message. Only you, the holder of the private key, will be able to correctly understand the challenge and produce the proper response.

This challenge-response phase happens behind the scenes and is invisible to the user. As long as you hold the private key, which is typically stored in the ~/.ssh/ directory, your SSH client should be able to reply with the appropriate response to the server.

A private key is a guarded secret and as such it is advisable to store it on disk in an encrypted form. When the encrypted private key is required, a passphrase must first be entered in order to decrypt it. While this might superficially appear as though you are providing a login password to the SSH server, the passphrase is only used to decrypt the private key on the local system. The passphrase is not transmitted over the network.

Generating an SSH key pair

An SSH key pair can be generated by running the ssh-keygen command, defaulting to 3072-bit RSA (and SHA256) which the ssh-keygen(1) man page says is 'generally considered sufficient' and should be compatible with virtually all clients and servers:

The randomart image was introduced in OpenSSH 5.1 as an easier means of visually identifying the key fingerprint.

You can also add an optional comment field to the public key with the -C switch, to more easily identify it in places such as ~/.ssh/known_hosts, ~/.ssh/authorized_keys and ssh-add -L output. For example:

will add a comment saying which user created the key on which machine and when.

Choosing the authentication key type

OpenSSH supports several signing algorithms (for authentication keys) which can be divided in two groups depending on the mathematical properties they exploit:

1. DSA and RSA, which rely on the practical difficulty of factoring the product of two large prime numbers,
2. ECDSA and Ed25519, which rely on the elliptic curve discrete logarithm problem. (example)

Elliptic curve cryptography (ECC) algorithms are a more recent addition to public key cryptosystems. One of their main advantages is their ability to provide the same level of security with smaller keys, which makes for less computationally intensive operations (i.e. faster key creation, encryption and decryption) and reduced storage and transmission requirements.

OpenSSH 7.0 deprecated and disabled support for DSA keys due to discovered vulnerabilities, therefore the choice of cryptosystem lies within RSA or one of the two types of ECC.

#RSA keys will give you the greatest portability, while #Ed25519 will give you the best security but requires recent versions of client & server[2]^{[dead link 2020-04-02 ⓘ]}. #ECDSA is likely more compatible than Ed25519 (though still less than RSA), but suspicions exist about its security (see below).

RSA

ssh-keygen defaults to RSA therefore there is no need to specify it with the -t option. It provides the best compatibility of all algorithms but requires the key size to be larger to provide sufficient security.

Minimum key size is 1024 bits, default is 3072 (see ssh-keygen(1)) and maximum is 16384.

If you wish to generate a stronger RSA key pair (e.g. to guard against cutting-edge or unknown attacks and more sophisticated attackers), simply specify the -b option with a higher bit value than the default:

Be aware though that there are diminishing returns in using longer keys.[3][4] The GnuPG FAQ reads: 'If you need more security than RSA-2048 offers, the way to go would be to switch to elliptical curve cryptography — not to continue using RSA'.[5]

On the other hand, the latest iteration of the NSA Fact Sheet Suite B Cryptography^{[dead link 2020-04-02 ⓘ]} suggests a minimum 3072-bit modulus for RSA while '[preparing] for the upcoming quantum resistant algorithm transition'.[6]

ECDSA

The Elliptic Curve Digital Signature Algorithm (ECDSA) was introduced as the preferred algorithm for authentication in OpenSSH 5.7. Some vendors also disable the required implementations due to potential patent issues.

There are two sorts of concerns with it:

1. Political concerns, the trustworthiness of NIST-produced curves being questioned after revelations that the NSA willingly inserts backdoors into softwares, hardware components and published standards were made; well-known cryptographers haveexpresseddoubts about how the NIST curves were designed, and voluntary tainting has already beenproved in the past.
2. Technical concerns, about the difficulty to properly implement the standard and the slowness and design flaws which reduce security in insufficiently precautious implementations.

Both of those concerns are best summarized in libssh curve25519 introduction. Although the political concerns are still subject to debate, there is a clear consensus that #Ed25519 is technically superior and should therefore be preferred.

Ed25519

Ed25519 was introduced in OpenSSH 6.5 of January 2014: 'Ed25519 is an elliptic curve signature scheme that offers better security than ECDSA and DSA and good performance'. Its main strengths are its speed, its constant-time run time (and resistance against side-channel attacks), and its lack of nebulous hard-coded constants.[7] See also this blog post by a Mozilla developer on how it works.

It is already implemented in many applications and libraries and is the default key exchange algorithm (which is different from key signature) in OpenSSH.

Ed25519 key pairs can be generated with:

There is no need to set the key size, as all Ed25519 keys are 256 bits.

Keep in mind that older SSH clients and servers may not support these keys.

Choosing the key location and passphrase

Upon issuing the ssh-keygen command, you will be prompted for the desired name and location of your private key. By default, keys are stored in the ~/.ssh/ directory and named according to the type of encryption used. You are advised to accept the default name and location in order for later code examples in this article to work properly.

When prompted for a passphrase, choose something that will be hard to guess if you have the security of your private key in mind. A longer, more random password will generally be stronger and harder to crack should it fall into the wrong hands.

It is also possible to create your private key without a passphrase. While this can be convenient, you need to be aware of the associated risks. Without a passphrase, your private key will be stored on disk in an unencrypted form. Anyone who gains access to your private key file will then be able to assume your identity on any SSH server to which you connect using key-based authentication. Furthermore, without a passphrase, you must also trust the root user, as he can bypass file permissions and will be able to access your unencrypted private key file at any time.

Changing the private key's passphrase without changing the key

If the originally chosen SSH key passphrase is undesirable or must be changed, one can use the ssh-keygen command to change the passphrase without changing the actual key. This can also be used to change the password encoding format to the new standard.

Managing multiple keys

It is possible — although controversial [8][9] — to use the same SSH key pair for multiple hosts.

On the other hand, it is rather easy to maintain distinct keys for multiple hosts by using the IdentityFile directive in your openSSH config file:

See ssh_config(5) for full description of these options.

Storing SSH keys on hardware tokens

SSH keys can also be stored on a security token like a smart card or a USB token. This has the advantage that the private key is stored securely on the token instead of being stored on disk. When using a security token the sensitive private key is also never present in the RAM of the PC; the cryptographic operations are performed on the token itself. A cryptographic token has the additional advantage that it is not bound to a single computer; it can easily be removed from the computer and carried around to be used on other computers.

Examples are hardware tokens are described in:

• Yubikey#OpenSSH Native OpenSSH support for FIDO/U2F keys

Copying the public key to the remote server

This article or section needs expansion.

Once you have generated a key pair, you will need to copy the public key to the remote server so that it will use SSH key authentication. The public key file shares the same name as the private key except that it is appended with a .pub extension. Note that the private key is not shared and remains on the local machine.

Simple method

If your key file is ~/.ssh/id_rsa.pub you can simply enter the following command.

If your username differs on remote machine, be sure to prepend the username followed by @ to the server name.

If your public key filename is anything other than the default of ~/.ssh/id_rsa.pub you will get an error stating /usr/bin/ssh-copy-id: ERROR: No identities found. In this case, you must explicitly provide the location of the public key.

If the ssh server is listening on a port other than default of 22, be sure to include it within the host argument.

Manual method

By default, for OpenSSH, the public key needs to be concatenated with ~/.ssh/authorized_keys. Begin by copying the public key to the remote server.

The above example copies the public key (id_ecdsa.pub) to your home directory on the remote server via scp. Do not forget to include the : at the end of the server address. Also note that the name of your public key may differ from the example given.

On the remote server, you will need to create the ~/.ssh directory if it does not yet exist and append your public key to the authorized_keys file.

The last two commands remove the public key file from the server and set the permissions on the authorized_keys file such that it is only readable and writable by you, the owner.

SSH agents

If your private key is encrypted with a passphrase, this passphrase must be entered every time you attempt to connect to an SSH server using public-key authentication. Each individual invocation of ssh or scp will need the passphrase in order to decrypt your private key before authentication can proceed.

An SSH agent is a program which caches your decrypted private keys and provides them to SSH client programs on your behalf. In this arrangement, you must only provide your passphrase once, when adding your private key to the agent's cache. This facility can be of great convenience when making frequent SSH connections.

An agent is typically configured to run automatically upon login and persist for the duration of your login session. A variety of agents, front-ends, and configurations exist to achieve this effect. This section provides an overview of a number of different solutions which can be adapted to meet your specific needs.

ssh-agent

ssh-agent is the default agent included with OpenSSH. It can be used directly or serve as the back-end to a few of the front-end solutions mentioned later in this section. When ssh-agent is run, it forks to background and prints necessary environment variables. E.g.

To make use of these variables, run the command through the eval command.

Once ssh-agent is running, you will need to add your private key to its cache:

If your private key is encrypted, ssh-add will prompt you to enter your passphrase. Once your private key has been successfully added to the agent you will be able to make SSH connections without having to enter your passphrase.

In order to start the agent automatically and make sure that only one ssh-agent process runs at a time, add the following to your ~/.bashrc:

This will run a ssh-agent process if there is not one already, and save the output thereof. If there is one running already, we retrieve the cached ssh-agent output and evaluate it which will set the necessary environment variables.

There also exist a number of front-ends to ssh-agent and alternative agents described later in this section which avoid this problem.

Start ssh-agent with systemd user

It is possible to use the systemd/User facilities to start the agent. Use this if you would like your ssh agent to run when you are logged in, regardless of whether x is running.

Add SSH_AUTH_SOCK DEFAULT='${XDG_RUNTIME_DIR}/ssh-agent.socket' to ~/.pam_environment. Then enable or start the service with the --userFree license key generator snag items. flag.

ssh-agent as a wrapper program

An alternative way to start ssh-agent (with, say, each X session) is described in this ssh-agent tutorial by UC Berkeley Labs. A basic use case is if you normally begin X with the startx command, you can instead prefix it with ssh-agent like so:

And so you do not even need to think about it you can put an alias in your .bash_aliases file or equivalent:

Doing it this way avoids the problem of having extraneous ssh-agent instances floating around between login sessions. Exactly one instance will live and die with the entire X session.

See the below notes on using x11-ssh-askpass with ssh-add for an idea on how to immediately add your key to the agent.

GnuPG Agent

The gpg-agent has OpenSSH agent emulation. See GnuPG#SSH agent for necessary configuration.

Keychain

Keychain is a program designed to help you easily manage your SSH keys with minimal user interaction. It is implemented as a shell script which drives both ssh-agent and ssh-add. A notable feature of Keychain is that it can maintain a single ssh-agent process across multiple login sessions. This means that you only need to enter your passphrase once each time your local machine is booted.

Installation

Install the keychain package.

Configuration

Add a line similar to the following to your shell configuration file, e.g. if using Bash:

In the above example,

• the --eval switch outputs lines to be evaluated by the opening eval command; this sets the necessary environments variables for SSH client to be able to find your agent.
• --quiet will limit output to warnings, errors, and user prompts.

Multiple keys can be specified on the command line, as shown in the example. By default keychain will look for key pairs in the ~/.ssh/ directory, but absolute path can be used for keys in non-standard location. You may also use the --confhost option to inform keychain to look in ~/.ssh/config for IdentityFile settings defined for particular hosts, and use these paths to locate keys.

See keychain --help or keychain(1) for details on setting keychain for other shells.

To test Keychain, simply open a new terminal emulator or log out and back in your session. It should prompt you for the passphrase of the specified private key(s) (if applicable), either using the program set in $SSH_ASKPASS or on the terminal.

Because Keychain reuses the same ssh-agent process on successive logins, you should not have to enter your passphrase the next time you log in or open a new terminal. You will only be prompted for your passphrase once each time the machine is rebooted.

Tips

• keychain expects public key files to exist in the same directory as their private counterparts, with a .pub extension. If the private key is a symlink, the public key can be found alongside the symlink or in the same directory as the symlink target (this capability requires the readlink command to be available on the system).

• to disable the graphical prompt and always enter your passphrase on the terminal, use the --nogui option. This allows to copy-paste long passphrases from a password manager for example.

• if you do not want to be immediately prompted for unlocking the keys but rather wait until they are needed, use the --noask option.

x11-ssh-askpass

The x11-ssh-askpass package provides a graphical dialog for entering your passhrase when running an X session. x11-ssh-askpass depends only on the libx11 and libxt libraries, and the appearance of x11-ssh-askpass is customizable. While it can be invoked by the ssh-add program, which will then load your decrypted keys into ssh-agent, the following instructions will, instead, configure x11-ssh-askpass to be invoked by the aforementioned Keychain script.

Install the keychain and x11-ssh-askpass packages.

Edit your ~/.xinitrc file to include the following lines, replacing the name and location of your private key if necessary. Be sure to place these commands before the line which invokes your window manager.

In the above example, the first line invokes keychain and passes the name and location of your private key. If this is not the first time keychain was invoked, the following two lines load the contents of $HOSTNAME-sh and $HOSTNAME-sh-gpg, if they exist. These files store the environment variables of the previous instance of keychain.

Calling x11-ssh-askpass with ssh-add

The ssh-add manual page specifies that, in addition to needing the DISPLAY variable defined, you also need SSH_ASKPASS set to the name of your askpass program (in this case x11-ssh-askpass). It bears keeping in mind that the default Arch Linux installation places the x11-ssh-askpass binary in /usr/lib/ssh/, which will not be in most people's PATH. This is a little annoying, not only when declaring the SSH_ASKPASS variable, but also when theming. You have to specify the full path everywhere. Both inconveniences can be solved simultaneously by symlinking:

This is assuming that ~/bin is in your PATH. So now in your .xinitrc, before calling your window manager, one just needs to export the SSH_ASKPASS environment variable:

and your X resources will contain something like:

Doing it this way works well with the above method on using ssh-agent as a wrapper program. You start X with ssh-agent startx and then add ssh-add to your window manager's list of start-up programs.

Theming

The appearance of the x11-ssh-askpass dialog can be customized by setting its associated X resources. Some examples are the .ad files at https://github.com/sigmavirus24/x11-ssh-askpass. See x11-ssh-askpass(1)^{[dead link 2019-05-05]} for full details.

Alternative passphrase dialogs

There are other passphrase dialog programs which can be used instead of x11-ssh-askpass. The following list provides some alternative solutions.

• ksshaskpass uses the KDE Wallet.
• openssh-askpass uses the Qt library.

pam_ssh

The pam_ssh project exists to provide a Pluggable Authentication Module (PAM) for SSH private keys. This module can provide single sign-on behavior for your SSH connections. On login, your SSH private key passphrase can be entered in place of, or in addition to, your traditional system password. Once you have been authenticated, the pam_ssh module spawns ssh-agent to store your decrypted private key for the duration of the session.

Git Linux Generate Ssh Key Windows 10

To enable single sign-on behavior at the tty login prompt, install the unofficial pam_ssh^AUR package.

Create a symlink to your private key file and place it in ~/.ssh/login-keys.d/. Replace the id_rsa in the example below with the name of your own private key file.

Edit the /etc/pam.d/login configuration file to include the text highlighted in bold in the example below. The order in which these lines appear is significiant and can affect login behavior.

In the above example, login authentication initially proceeds as it normally would, with the user being prompted to enter his user password. The additional auth authentication rule added to the end of the authentication stack then instructs the pam_ssh module to try to decrypt any private keys found in the ~/.ssh/login-keys.d directory. The try_first_pass option is passed to the pam_ssh module, instructing it to first try to decrypt any SSH private keys using the previously entered user password. If the user's private key passphrase and user password are the same, this should succeed and the user will not be prompted to enter the same password twice. In the case where the user's private key passphrase user password differ, the pam_ssh module will prompt the user to enter the SSH passphrase after the user password has been entered. The optional control value ensures that users without an SSH private key are still able to log in. In this way, the use of pam_ssh will be transparent to users without an SSH private key.

If you use another means of logging in, such as an X11 display manager like SLiM or XDM and you would like it to provide similar functionality, you must edit its associated PAM configuration file in a similar fashion. Packages providing support for PAM typically place a default configuration file in the /etc/pam.d/ directory.

Further details on how to use pam_ssh and a list of its options can be found in the pam_ssh(8) man page.

Generate Ssh Key Linux Github

Using a different password to unlock the SSH key

If you want to unlock the SSH keys or not depending on whether you use your key's passphrase or the (different!) login password, you can modify /etc/pam.d/system-auth to

For an explanation, see [10].

Known issues with pam_ssh

Work on the pam_ssh project is infrequent and the documentation provided is sparse. You should be aware of some of its limitations which are not mentioned in the package itself.

• Versions of pam_ssh prior to version 2.0 do not support SSH keys employing the newer option of ECDSA (elliptic curve) cryptography. If you are using earlier versions of pam_ssh you must use either RSA or DSA keys.

• The ssh-agent process spawned by pam_ssh does not persist between user logins. If you like to keep a GNU Screen session active between logins you may notice when reattaching to your screen session that it can no longer communicate with ssh-agent. This is because the GNU Screen environment and those of its children will still reference the instance of ssh-agent which existed when GNU Screen was invoked but was subsequently killed in a previous logout. The Keychain front-end avoids this problem by keeping the ssh-agent process alive between logins.

pam_exec-ssh

As an alternative to pam_ssh you can use pam_exec-ssh^AUR. It is a shell script that uses pam_exec. Help for configuration can be found upstream.

GNOME Keyring

If you use the GNOME desktop, the GNOME Keyring tool can be used as an SSH agent. See the GNOME Keyring article for further details.

Store SSH keys with Kwallet

For instructions on how to use kwallet to store your SSH keys, see KDE Wallet#Using the KDE Wallet to store ssh key passphrases.

KeePass2 with KeeAgent plugin

KeeAgent is a plugin for KeePass that allows SSH keys stored in a KeePass database to be used for SSH authentication by other programs.

Ssh Generate Key

• Supports both PuTTY and OpenSSH private key formats.
• Works with native SSH agent on Linux/Mac and with PuTTY on Windows.

See KeePass#Plugin Installation in KeePass or install the keepass-plugin-keeagent package.

This agent can be used directly, by matching KeeAgent socket: KeePass -> Tools -> Options -> KeeAgent -> Agent mode socket file -> %XDG_RUNTIME_DIR%/keeagent.socket-and environment variable:export SSH_AUTH_SOCK='$XDG_RUNTIME_DIR'/keeagent.socket'.

KeePassXC

The KeePassXC fork of KeePass supports being used as an SSH agent by default. It is also compatible with KeeAgent's database format.

Troubleshooting

Key ignored by the server

• If it appears that the SSH server is ignoring your keys, ensure that you have the proper permissions set on all relevant files.

For the local machine:

For the remote machine:

• If that does not solve the problem you may try temporarily setting StrictModes to no in /etc/ssh/sshd_config. If authentication with StrictModes off is successful, it is likely an issue with file permissions persists.

• Make sure keys in ~/.ssh/authorized_keys are entered correctly and only use one single line.
• Make sure the remote machine supports the type of keys you are using: some servers do not support ECDSA keys, try using RSA or DSA keys instead, see #Generating an SSH key pair.
• You may want to use debug mode and monitor the output while connecting:

Generate Ssh Key Putty

See also

• OpenSSH key management: Part 1, Part 2, Part 3