• Generate Ssh_host_ecdsa_key Account
• Generate Ssh_host_ecdsa_key Form
• Generate Ssh_host_ecdsa_key Excel
• Ecdsa Host Key Has Changed
• Ecdsa Key

This repo contains a showcase of how to use SSH certificates (for hosts & users) generated by step-ca using the step CLI'sssh sub-command.

So this is a new server with ubuntu freshly installed, is it normal that the /etc/ssh/ directory already has sshhostecdsakey and sshhostrsakey files on it? I can also see.pub files for these as well. Does this mean whoever set up the server can access it using those key files? I want to be the only person who can log in to my server. Aug 19, 2019  This tutorial will guide you through the steps on how to generate and set up SSH keys on CentOS 7. We also cover connecting to a remote server using the keys and disabling password authentication. Before you start. Check for Existing Keys.

If you haven't already you should read our blogpost on why SSH certificatesare better than SSH public keys for authentication and how you can achieve defacto SSH Single Sign-on while doing away with pesky public key managementacross your server fleet.

This document describes:

• how to provision step-ca to issue SSH host & user certificates.
• how sshd is configured to accept user certificates for client authentication using a CA key.
• how sshd is configured to present a host certificate for host authentication on the client-side.
• how to configure a user's ssh to accept host certificate signed by a CA key.
• how to configure a user's ssh to present a user certificate for authentication on the server-side.

The code in this repo comes with a pre-generated PKI. You will need stepv0.13.3+ (installation docs)and Vagrant (plus a provider likeVirtualBox) installed locally.

Setup VM

We're going to run a CA in your local environment, and we'll use ssh toconnect to a Vagrant VM(representing a remote host) that has sshd pre-configured to acceptuser certificates signed by our CA.

With Vagrant installed, run the following commands inside the repo:

Configure ssh client to accept host certs

Go ahead and follow the instructions printed by Vagrant. This will enable yourlocal SSH client to accept SSH host certificates (signed by the root SSH hostprivate key). The following command will append the SSH host CA key(root SSH host public key corresponding to the root SSH host private key) toyour local known_hosts file:

You can also find the root SSH host CA key stored atstep/certs/ssh_host_key.pub in this repo.

Certificates bind names to public keys. This SSH host certificate has theidentity testhost which is why the following entry must be added to thelocal /etc/hosts file on the VM:

Configure sshd to accept user certs

Vagrant has already configured sshd on testhost, the VMgenerated by Vagrant. Please note that for demo purposes the PKI is shared withthe VM using a shared directory mount. Below you can see the relevant linesfrom the testhost VM's sshd_config:

• TrustUserCAKeys: The root SSH user public key used to verify SSHuser certificates.
• HostKey: The SSH private key specific to this host.
• HostCertificate: The SSH public certificate that uniquelyidentifies this host (signed by the root SSH host private key).

Login to VM via SSH user cert

A valid user certificate is required to log into the testhost VM. Using thestep CLI we will authenticate with our SSH-enabled CA and fetch a new SSHcertificate.

In one terminal window run the following command to startup your CA (passwordis password):

In another terminal window run:

NOTE: step-ca enforces authentication for all certificate requests and usesthe concept ofprovisionersto carry out this enforcement. Provisioners are configured instep/config/ca.json. Authenticating as one of the sanctioned provisionersindicates to step-ca that you have the right to provisione newcertificates. In the above invocation of step ssh certificate we haveauthenticated our request using a JWK provisioner, which simply requires apassword to decrypt a private key. However, there are a handful of supportedprovisioners, each with it's own authentication methods. The OIDC provisioneris particularly interesting for SSH user certificates because it enablesSingle Sign-On SSH.

Conveniently, step ssh certificate adds the new SSH user certificate to yourlocal ssh agent. The default lifetime of an SSH certificate from step-ca is4hrs. The lifetime can be configured using command line options (run step ssh certificate -h for documentation and examples).

Generate Ssh_host_ecdsa_key Account

Boom! As you can see the testhost VM will welcome you with a matchingtestuser@testhost prompt.

Learn how to use OAuth OIDC proviers like Gsuite or Instance Identity Documentsto bootstrap SSH host and user certificates in our blog post If you’re not using SSHcertificates you’re doing SSHwrong or check out thestep CLI reference athttps://smallstep.com/docs/cli/ssh/.

Generate ssh host certificates

This example repo includes a pre-generated SSH host certificate and key. To replace itor generate SSH certificates for other hosts running following command:

Where --principal identifies the hostname(s) (ideally FQDNs) for the machine.For a single principal you can short cut the command to:

Generate your own PKI for step-ca

We recommend using your own PKI for usage outside of this example. You caninitialize your step-ca withboth X509 and SSH certificates using the following command:

Now you can launch your instance ofstep-ca with your own PKI likeso:

Please note that after you regenerate ssh_host_key.pub and ssh_user_key.pubyou will have to reconfigure ssh and sshd for clients and hosts to acceptthe new CA keys. Check out this host bootstrapping script forconfiguration examples.

Introduction

Secure Shell (SSH) is an encrypted protocol used by Linux users to connect to their remote servers.

Generally, there are two ways for clients to access their servers – using password based authentication or public key based authentication.

Using SSH keys for authentication is highly recommended, as a safer alternative to passwords.

This tutorial will guide you through the steps on how to generate and set up SSH keys on CentOS 7. We also cover connecting to a remote server using the keys and disabling password authentication.

1. Check for Existing Keys

Prior to any installation, it is wise to check whether there are any existing keys on the client machines.

Open the terminal and list all public keys stored with the following command:

The output informs you about any generated keys currently on the system. If there aren’t any, the message tells you it cannot access /.ssh/id_*.pub , as there is no such file or directory.

2. Verify SSH is Installed

To check if thw package is installed, run the command:

If you already have SSH, the output tells you which version it is running. Currently, the latest version is OpenSSH 8.0/8.0p1.

Note: Refer to our guide If you need to install and enable SSH on your CentOS system.

Steps to Creating SSH keys on CentOS

1. Start by logging into the source machine (local server) and creating a 2048-bit RSA key pair using the command:

If you want to tighten up security measures, you can create a 4096-bit key by adding the -b 4096 flag:

2. After entering the command, you should see the following prompt:

3. To save the file in the suggested directory, press Enter. Alternatively, you can specify another location.

Note: If you already have a key pair in the proposed location, it is advisable to pick another directory. Otherwise it will overwrite existing SSH keys.

4. Next, the prompt will continue with:

Although creating a passphrase isn’t mandatory, it is highly advisable.

5. Finally, the output will end by specifying the following information:

Now you need to add the public key to the remote CentOS server.

You can copy the public SSH key on the remote server using several different methods:

1. using the ssh-copy-id script
2. using Secure Copy (scp)
3. manually copying the key

The fastest and easiest method is by utilizing ssh-copy-id. If the option is available, we recommend using it. Otherwise, try any of the other two noted.

1. Start by typing the following command, specifying the SSH user account, and the IP address of the remote host:

If it is the first time your local computer is accessing this specific remote server you will receive the following output:

2. Confirm the connection – type yes and hit Enter.

3. Once it locates the id_rsa.pub key created on the local machine, it will ask you to provide the password for the remote account. Type in the password and hit Enter.

4. Once the connection has been established, it adds the public key on the remote server. This is done by copying the ~/.ssh/id_rsa.pub file to the remote server’s ~/.ssh directory. You can locate it under the name authorized_keys.

5. Lastly, the output tells you the number of keys added, along with clear instructions on what to do next:

1. First, set up an SSH connection with the remote user:

2. Next, create the ~/.ssh directory as well as the authorized_keys file:

3. Use the chmod command to change the file permission:

chmod 700 makes the file executable, while chmod 600 allows the user to read and write the file.

4. Now, open a new terminal session, on the local computer.

5. Copy the content from id_rsa.pub (the SSH public key) to the previously created authorized_keys file on the remote CentOS server by typing the command:

With this, the public key has been safely stored on the remote account.

1. To manually add the public SSH key to the remote machine, you first need to open the content from the ~/.ssh/id_rsa.pub file:

Generate Ssh_host_ecdsa_key Form

2. As in the image below, the key starts with ssh-rsa and ends with the username of the local computer and hostname of the remote machine:

3. Copy the content of the file, as you will need later.

4. Then, in the terminal window, connect to the remote server on which you wish to copy the public key. Use the following command to establish the connection:

5. Create a ~/.ssh directory and authorized_keys file on the CentOS server with the following command:

6. Change their file permission by typing:

7. Next, open the authorized_keys file with an editor of your preference. For example, to open it with Nano, type:

8. Add the public key, previously copied in step 2 of this section, in a new line in (under the existing content).

9. Save the changes and close the file.

10. Finally, log into the server to verify that everything is set up correctly.

Generate Ssh_host_ecdsa_key Excel

Once you have completed the previous steps (creating an RSA Key Pair and copying the Public Key to the CentOS server), you will be able to connect to the remote host without typing the password for the remote account.

All you need to do is type in the following command:

If you didn’t specify a passphrase while creating the SSH key pair, you will automatically log in the remote server.

Otherwise, type in the passphrase you supplied in the initial steps and press Enter.

Once the shell confirms the key match, it will open a new session for direct communication with the server.

Although you managed to access the CentOS server without having to provide a password, it still has a password-based authentication system running on the machine. This makes it a potential target for brute force attacks.

Enter CSR and Private Key command. Generate a private key and CSR by running the following command: Here is the plain text version to copy and paste into your terminal: openssl req -new -newkey rsa:2048 -nodes -keyout server.key -out server.csr. Note: Replace “server ” with the domain name you intend to secure. Enter your CSR details. The following sections describe how to use OpenSSL to generate a CSR for a single host name. If you want to generate a CSR for multiple host names, we recommend using the Cloud Control Panel or the MyRackspace Portal. Install OpenSSL. Check whether OpenSSL is installed by using the following command: CentOS® and Red Hat® Enterprise Linux®. Mar 30, 2015  You will also be prompted for information to populate the CSR. At the command line, type: $ openssl req -new -key /path/to/wwwservercom.key -out /path/to/wwwservercom.csr. This will fire up OpenSSL, instruct it to generate a certificate signing request, and let it know to use a key we are going to specify – the one we just created, in. Openssl command to generate csr and key. What I am trying to do is, create a CSR and with a private key that is password protected (the key). In OpenSSL I can create a private key with a password like so: openssl genrsa -des3 -out privkey.pem 2048 Is there some way I can use the key I just created and generate a CSR using the key?

Ecdsa Host Key Has Changed

You should disable password authentication entirely by following the outlined steps.

Ecdsa Key

Note: Consider performing the following steps through a non-root account with sudo privileges, as an additional safety layer.

1. Using the SSH keys, log into the remote CentOS server which has administrative privileges:

2. Next, open the SSH daemon configuration file using a text editor of your choice:

3. Look for the following line in the file:

4. Edit the configuration by changing the yes value to no. Thus, the directive should be as following:

5. Save the file and exit the text editor.
6. To enable the changes, restart the sshdservice using the command:

7. Verify the SSH connection to the server is still functioning correctly. Open a new terminal window and type in the command:

In this article, you learned how to generate SSH key pairs and set up an SSH key-based authentication. We also covered copying keys to your remote CentOS server, and disabling SSH password authentication.

Next, You Should Read: