Finally enable and start this service. Systemctl -user enable ssh-agent systemctl -user start ssh-agent. And, if you are using ssh version higher than 7.2. Echo 'AddKeysToAgent yes' /.ssh/config. This will instruct the ssh client to always add the key to a running agent, so there’s no need to ssh-add it. I would like to login to a remote server by executing sth. Like ssh remoteServer. The remote server can only be reached via a login server (which there are two of).There are two routes I would li. Welcome to my first official guide on Dev.to. Today I want to explain how you can setup SSH and Git o. Tagged with windows, ssh, git. Config.ssh.compression (boolean) - If false, this setting will not include the compression setting when ssh'ing into a machine. If this is not set, it will default to true and Compression=yes will be enabled with ssh. Config.ssh.connecttimeout (integer) - Number of seconds to wait for establishing an SSH connection to the guest. The first thing we are going to solve using this config file is to avoid having to add custom-named. But if you remove the keys from ssh-agent with ssh.

Azure DevOps Services | Azure DevOps Server 2020 | Azure DevOps Server 2019 | TFS 2018 - TFS 2015

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 Manager Core or Personal Access Tokens.

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 Azure DevOps 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 SSH public keys in the menu that appears.

2. 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. Also note that SSH keys stored in Azure DevOps expire after five years. If your key expires, you may upload a new key or the same one to continue accessing Azure DevOps via SSH.

5. Test the connection by running the following command: ssh -T git@ssh.dev.azure.com.If everything is working correctly, you'll receive a response which says: remote: Shell access is not supported.If not, see the section on Questions and troubleshooting.

Step 2: Add the public key to Azure DevOps

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 + 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.

5. Test the connection by running the following command: ssh -T git@ssh.dev.azure.com.If everything is working correctly, you'll receive a response which says: remote: Shell access is not supported.If not, see the section on Questions and troubleshooting.

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 Visual Studio Team Services 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.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

To prevent problems, Windows users should 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?

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, perform these two tasks:

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: How do I fix errors that mention 'no matching key exchange method found'?

A: Git for Windows 2.25.1 shipped with a new version of OpenSSH which removed some key exchange protocols by default.Specifically, diffie-hellman-group14-sha1 has been identified as problematic for some Azure DevOps Server and TFS customers.You can work around the problem by adding the following to your SSH configuration (~/.ssh/config):

Replace <your-azure-devops-host> with the hostname of your Azure DevOps or TFS server, like tfs.mycompany.com.

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.

Q: What do I do if I'm still prompted for my password and GIT_SSH_COMMAND='ssh -v' git fetch shows no mutual signature algorithm?

A: Some Linux distributions, such as Fedora Linux, have crypto policies that require stronger SSH signature algorithms than Azure DevOps supports (as of January 2021). There's an open feature request to add this support.

You can work around the issue by adding the following code to your SSH configuration (~/.ssh/config):

Replace ssh.dev.azure.com with the correct host name if you use Azure DevOps Server.

SSH

• SSH
  • SSH Keys
• Utilizing the SSH Agent
  • Basic Usage
  • SSH-Agent Forwarding
• Advanced usage

SSH stands for Secure Shell. It is used to establish a secureconnection to an account on another computer to access files or runprograms without physical access to the machine.

At Western, we allow you to ssh into our Linux COW (Cluster OfWorkstations) and Lab Systems from anywhere inside or outside the University to accessthe files in your account's homedirectory.

Accessing Linux with SSH

By default, SSH will use port 22 forreasons. The CS department uses port922 for a little additional security. This means the ssh commandwill need the -p flag to specify port 922.

SSH Config

If you find typing the whole ssh -p 922 ${username}@${hostname}.cs.wwu.eduline into your terminal exhausting, there is a perfect solution for you:SSH configuration!

SSH configuration will allow you to use any shorthand alias to connectto a remote server, for example ssh linux for ssh -p 922 ${username}@linux.cs.wwu.edu. Your ssh config file is found at~/.ssh/config.

Here is an example of an ssh config file for linux.cs.wwu.edu:

Note:

• You can call the Host anything, it does not have to be linux. It isjust your alias for the ssh command.
• Replace ${username} with your username or the account you havepermission to use.

Getting files with SCP

To copy files from a remote machine that you can access with ssh, youcan use Secure Copy, scp.

For Example, if you want to download document.txt using linux.cs.wwu.edu, from your local machine, use the following command:

Assuming this file exists, this command will copy the filedocument.txt from your CS account homedirectory(denoted with ~) to your local machine's Documents directory.

Notice that scp uses a capital P for its port option flag.

This can also work in the opposite direction: copying files from yourlocal computer to a remote destination.

This command will copy the file document.txt from your local machineto the home directory of your CS account renamed to copied.txt.

SSH Keys

Using an SSH key will make your login more secure. This section willgive you the skinny on SSH keys and key usage. At the end of thissection will be a link to a more in depth description on SSH security.

SSH keys are generated in a public/private keypair. When you ssh intoanother machine, it sends your public key to that machine's~/.ssh/authorized_keys file. When you connect to that machine later,it checks your private key against the public key it has throughcryptographic algorithms to verify your identity.

Your private key should never be given out to ANYBODY!

Ssh Agent Configuration

Western uses EdDSA in the form of Ed25519for our key encryption method. To generate the key pair use this commandin the terminal:

This command will ask for a passphrase and then generate two files inthe ~/.ssh directory: id_ed25519 and id_ed25519.pub. The former isyour private key (Keep it secret! Keep it safe!), and the latteris your public key signified with the .pub extension.

Here is an example of what the interaction will look like:

• note: the password field appears blank because passwordcharacters are hidden in the terminal.
• also note: if you leave the Enter the file in which to save the key line blank, it will default to the path in the parentheses.

Ssh Agent Setup

Getting public key to WWU CS Systems from Off Site

After generating your key, you will need to send the public key to the /home/${username}/.ssh directory of the system you will access. On the CS Network, your directory will get mounted anywhere you would normally sign in for academic use (this may not apply to research or project systems). To get the public key from your personal system to the CS location, ssh-copy-id should be used.

So if strongbad were to connect to linux.cs.wwu.edu the command would appear as below:

Other Key Formats

While all of the Computer Science department's SSH servers accept newerkey formats like Ed25519this is not universally true. Some services outside the university mightnot. You may wish to consider another algorithm likeRSA orECDSA.You can generate those types of keys by changing which argument you giveto ssh-keygen's -t flag. For example, if you wanted to generate a4096-bit RSA key you would do

You are now all set to use these keys!

Let's say you want to see information on machine B but can only do sogoing through a specific port. Instructions can be found here.

While SSH keys allow for a more secure connection they still do notresolve the problem of having to enter a password for yourpublic/private key each time you want to ssh into a system. ssh-agentand ssh-add solve this problem by decrypting the key and storing it inmemory so that the user only needs to type in his/her password once.

Basic Usage

Step 1 Starting ssh-agent

The following command will start ssh-agent

Step 2 Add keys to ssh-agent

ssh-add will add the default key (id_rsa) and keep the passphrasestored in memory so that you do not have to keep typing it.

ssh-add will ask you for your password and store it for as long as youare logged in.

See loaded Keys

If you wish to see all of your loaded keys, use the command:

SSH-Agent Forwarding

Mac store macbook pro. If you would like to utilize SSH Keys rather than typing your password multiple times, a user can load their SSH Keys and pass their agent information across the SSH connection.

After generating SSH keys one needs to add it to their authorized_keys file. This is located at /home/${username}/.ssh/. If it is not there one needs to make the file. The cat line appends the public key to the end of the authorized_keys file, creating one as well if one does not exist.

After this is complete, one can use the ssh_key to connect. To do this, one would leverage the -A and -i flags. For an example, if your cs username is strongbad, your private key is named id_ed25519_strongbad and you are accessing labs.cs.wwu.edu, the command would look like the below code block.

Leveraging your SSH config

As was demonstrated in the SSH config examination, the SSH config can make things easier. This is achieved by adding the IdentityFile and ForwardAgent options shown below.

After doing this, all strongbad would need to do is:

If you had not entered a password for your SSH key yet (all SSH keys should have a password), it would prompt you to enter that password, and then automatically sign you in. After this, once the key is loaded, you would not need to enter that password again.

SSH is a very deep tool and can be used in a number of empowering ways.

X Forwarding

If you have an X server running on your local system (XOrg onBSD/Linux, XQuartz on macOS, or VcXsrc on Windows) you may want theoption to forward your X traffic from the lab machine to your localsystem. Adding the -Y flag to ssh will do this for you, andlabs.cs.wwu.edu will automatically pass it on to the lab system thatit puts you on. Alternatively you can update your ~/.ssh/config labsentry with the following lines:

When it comes to X forwarding, compression can really help speedthings up. If you are not doing X forwarding it is not needed, and canoften slow things down.

Let's look at a sample X forwarding session to see if it works:

This created a window on my local desktop, but the application wasrunning on the remote lab machine!