Generate Key File From Crt Ubuntu

Contents Generating RSA Keys

1. Openssl Create Private Key From Crt
2. Generate Key File From Crt Ubuntu Download

Parent page: Internet and Networking >> SSH

Public key authentication is more secure than password authentication. This is particularly important if the computer is visible on the internet. If you don't think it's important, try logging the login attempts you get for the next week. My computer - a perfectly ordinary desktop PC - had over 4,000 attempts to guess my password and almost 2,500 break-in attempts in the last week alone.

With public key authentication, the authenticating entity has a public key and a private key. Each key is a large number with special mathematical properties. The private key is kept on the computer you log in from, while the public key is stored on the .ssh/authorized_keys file on all the computers you want to log in to. When you log in to a computer, the SSH server uses the public key to 'lock' messages in a way that can only be 'unlocked' by your private key - this means that even the most resourceful attacker can't snoop on, or interfere with, your session. As an extra security measure, most SSH programs store the private key in a passphrase-protected format, so that if your computer is stolen or broken in to, you should have enough time to disable your old public key before they break the passphrase and start using your key. Wikipedia has a more detailed explanation of how keys work.

The certificate is made out of your public key. The public and private keys are completely separate (by definition) and you can't generate one from the other. How was this new.crt file generated? There just has to be a key file and a CSR somewhere! – Alexios Jan 7 '14 at 10:00. Crt and key files represent both parts of a certificate, key being the private key to the certificate and crt being the signed certificate. It's only one of the ways to generate certs, another way would be having both inside a pem file or another in a p12 container.

Public key authentication is a much better solution than passwords for most people. In fact, if you don't mind leaving a private key unprotected on your hard disk, you can even use keys to do secure automatic log-ins - as part of a network backup, for example. Different SSH programs generate public keys in different ways, but they all generate public keys in a similar format:

Ubuntu: Creating a trusted CA and SAN certificate using OpenSSL There are numerous articles I’ve written where a certificate is a prerequisite for deploying a piece of infrastructure. This article will guide you through creating a trusted CA (Certificate Authority), and then using that to sign a server certificate that supports SAN ( Subject Alternative Name ).

Key-based authentication is the most secure of several modes of authentication usable with OpenSSH, such as plain password and Kerberos tickets. Key-based authentication has several advantages over password authentication, for example the key values are significantly more difficult to brute-force, or guess than plain passwords, provided an ample key length. Other authentication methods are only used in very specific situations.

SSH can use either 'RSA' (Rivest-Shamir-Adleman) or 'DSA' ('Digital Signature Algorithm') keys. Both of these were considered state-of-the-art algorithms when SSH was invented, but DSA has come to be seen as less secure in recent years. RSA is the only recommended choice for new keys, so this guide uses 'RSA key' and 'SSH key' interchangeably.

Key-based authentication uses two keys, one 'public' key that anyone is allowed to see, and another 'private' key that only the owner is allowed to see. To securely communicate using key-based authentication, one needs to create a key pair, securely store the private key on the computer one wants to log in from, and store the public key on the computer one wants to log in to.

Using key based logins with ssh is generally considered more secure than using plain password logins. This section of the guide will explain the process of generating a set of public/private RSA keys, and using them for logging into your Ubuntu computer(s) via OpenSSH.

The first step involves creating a set of RSA keys for use in authentication.

This should be done on the client.

To create your public and private SSH keys on the command-line:

You will be prompted for a location to save the keys, and a passphrase for the keys. This passphrase will protect your private key while it's stored on the hard drive:

Your public key is now available as

.ssh/id_rsa.pub

in your home folder.

Congratulations! You now have a set of keys. Now it's time to make your systems allow you to login with them

Choosing a good passphrase

You need to change all your locks if your RSA key is stolen. Otherwise the thief could impersonate you wherever you authenticate with that key.

An SSH key passphrase is a secondary form of security that gives you a little time when your keys are stolen. If your RSA key has a strong passphrase, it might take your attacker a few hours to guess by brute force. That extra time should be enough to log in to any computers you have an account on, delete your old key from the

.ssh/authorized_keys

file, and add a new key.

Your SSH key passphrase is only used to protect your private key from thieves. It's never transmitted over the Internet, and the strength of your key has nothing to do with the strength of your passphrase.

Openssl Create Private Key From Crt

The decision to protect your key with a passphrase involves convenience x security. Note that if you protect your key with a passphrase, then when you type the passphrase to unlock it, your local computer will generally leave the key unlocked for a time. So if you use the key multiple times without logging out of your local account in the meantime, you will probably only have to type the passphrase once.

If you do adopt a passphrase, pick a strong one and store it securely in a password manager. You may also write it down on a piece of paper and keep it in a secure place. If you choose not to protect the key with a passphrase, then just press the

return

when ssh-keygen asks.

Key Encryption Level

Note: The default is a 2048 bit key. You can increase this to 4096 bits with the -b flag (Increasing the bits makes it harder to crack the key by brute force methods).

Password Authentication

The main problem with public key authentication is that you need a secure way of getting the public key onto a computer before you can log in with it. If you will only ever use an SSH key to log in to your own computer from a few other computers (such as logging in to your PC from your laptop), you should copy your SSH keys over on a memory stick, and disable password authentication altogether. If you would like to log in from other computers from time to time (such as a friend's PC), make sure you have a strong password.

The key you need to transfer to the host is the public one. If you can log in to a computer over SSH using a password, you can transfer your RSA key by doing the following from your own computer:

Where

<username>

and

<host>

should be replaced by your username and the name of the computer you're transferring your key to.

Due to this bug, you cannot specify a port other than the standard port 22. You can work around this by issuing the command like this:

ssh-copy-id '<username>@<host> -p <port_nr>'

. If you are using the standard port 22, you can ignore this tip.

Another alternative is to copy the public key file to the server and concatenate it onto the authorized_keys file manually. It is wise to back that up first:

You can make sure this worked by doing:

You should be prompted for the passphrase for your key:

Enter passphrase for key '/home/<user>/.ssh/id_rsa':

Enter your passphrase, and provided host is configured to allow key-based logins, you should then be logged in as usual.

Encrypted Home Directory

If you have an encrypted home directory, SSH cannot access your

authorized_keys

file because it is inside your encrypted home directory and won't be available until after you are authenticated. Therefore, SSH will default to password authentication.

To solve this, create a folder outside your home named

/etc/ssh/<username>

(replace '<username>' with your actual username). This directory should have 755 permissions and be owned by the user. Move the

authorized_keys

file into it. The

authorized_keys

file should have 644 permissions and be owned by the user.

Then edit your

/etc/ssh/sshd_config

and add:

Finally, restart ssh with:

The next time you connect with SSH you should not have to enter your password.

username@host's password:

If you are not prompted for the passphrase, and instead get just the

It's helpful to practice this onyour computer before you actually start using it with your e-mail messages. Later, this will notbe the case.Now you are ready to start signing and encrypting messages.

prompt as usual with password logins, then read on. There are a few things which could prevent this from working as easily as demonstrated above. On default Ubuntu installs however, the above examples should work. If not, then check the following condition, as it is the most frequent cause:

On the host computer, ensure that the

/etc/ssh/sshd_config

contains the following lines, and that they are uncommented;

If not, add them, or uncomment them, restart OpenSSH, and try logging in again. If you get the passphrase prompt now, then congratulations, you're logging in with a key!

Permission denied (publickey)

If you're sure you've correctly configured

sshd_config

, copied your ID, and have your private key in the

.ssh

directory, and still getting this error:

Permission denied (publickey).

Chances are, your

/home/<user>

or

~/.ssh/authorized_keys

permissions are too open by OpenSSH standards. You can get rid of this problem by issuing the following commands:

Error: Agent admitted failure to sign using the key.

This error occurs when the ssh-agent on the client is not yet managing the key. Issue the following commands to fix:

This command should be entered after you have copied your public key to the host computer.

Debugging and sorting out further problems

The permissions of files and folders is crucial to this working. You can get debugging information from both the client and server.

if you think you have set it up correctly , yet still get asked for the password, try starting the server with debugging output to the terminal.

To connect and send information to the client terminal

No matter how your public key was generated, you can add it to your Ubuntu system by opening the file

.ssh/authorized_keys

in your favourite text editor and adding the key to the bottom of the file. You can also limit the SSH features that the key can use, such as disallowing port-forwarding or only allowing a specific command to be run. This is done by adding 'options' before the SSH key, on the same line in the

authorized_keys

file. For example, if you maintain a CVS repository, you could add a line like this:

When the user with the specified key logged in, the server would automatically run

/usr/bin/cvs server

, ignoring any requests from the client to run another command such as a shell. For more information, see the sshd man page. /755

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The Application Gateway v2 SKU introduces the use of Trusted Root Certificates to allow backend servers. This removes authentication certificates that were required in the v1 SKU. The root certificate is a Base-64 encoded X.509(.CER) format root certificate from the backend certificate server. It identifies the root certificate authority (CA) that issued the server certificate and the server certificate is then used for the TLS/SSL communication.

Application Gateway trusts your website's certificate by default if it's signed by a well-known CA (for example, GoDaddy or DigiCert). You don't need to explicitly upload the root certificate in that case. For more information, see Overview of TLS termination and end to end TLS with Application Gateway. However, if you have a dev/test environment and don't want to purchase a verified CA signed certificate, you can create your own custom CA and create a self-signed certificate with it.

Note

Self-signed certificates are not trusted by default and they can be difficult to maintain. Also, they may use outdated hash and cipher suites that may not be strong. For better security, purchase a certificate signed by a well-known certificate authority.

In this article, you will learn how to:

• Create your own custom Certificate Authority
• Create a self-signed certificate signed by your custom CA
• Upload a self-signed root certificate to an Application Gateway to authenticate the backend server

Prerequisites

• OpenSSL on a computer running Windows or Linux

  While there could be other tools available for certificate management, this tutorial uses OpenSSL. You can find OpenSSL bundled with many Linux distributions, such as Ubuntu.

• A web server

  For example, Apache, IIS, or NGINX to test the certificates.

• An Application Gateway v2 SKU

  If you don't have an existing application gateway, see Quickstart: Direct web traffic with Azure Application Gateway - Azure portal.

Create a root CA certificate

Create your root CA certificate using OpenSSL.

Create the root key

1. Sign in to your computer where OpenSSL is installed and run the following command. This creates a password protected key.

2. At the prompt, type a strong password. For example, at least nine characters, using upper case, lower case, numbers, and symbols.

Generate Key File From Crt Ubuntu Download

Create a Root Certificate and self-sign it

1. Use the following commands to generate the csr and the certificate.

   The previous commands create the root certificate. You'll use this to sign your server certificate.

2. When prompted, type the password for the root key, and the organizational information for the custom CA such as Country, State, Org, OU, and the fully qualified domain name (this is the domain of the issuer).

Create a server certificate

Next, you'll create a server certificate using OpenSSL.

Create the certificate's key

Use the following command to generate the key for the server certificate.

Create the CSR (Certificate Signing Request)

The CSR is a public key that is given to a CA when requesting a certificate. The CA issues the certificate for this specific request.

Note

The CN (Common Name) for the server certificate must be different from the issuer's domain. For example, in this case, the CN for the issuer is www.contoso.com and the server certificate's CN is www.fabrikam.com.

1. Use the following command to generate the CSR:

2. When prompted, type the password for the root key, and the organizational information for the custom CA: Country, State, Org, OU, and the fully qualified domain name. This is the domain of the website and it should be different from the issuer.

Generate the certificate with the CSR and the key and sign it with the CA's root key

1. Use the following command to create the certificate:

Verify the newly created certificate

1. Use the following command to print the output of the CRT file and verify its content:

2. Verify the files in your directory, and ensure you have the following files:

   • contoso.crt
   • contoso.key
   • fabrikam.crt
   • fabrikam.key

Configure the certificate in your web server's TLS settings

In your web server, configure TLS using the fabrikam.crt and fabrikam.key files. If your web server can't take two files, you can combine them to a single .pem or .pfx file using OpenSSL commands.

IIS

For instructions on how to import certificate and upload them as server certificate on IIS, see HOW TO: Install Imported Certificates on a Web Server in Windows Server 2003.

For TLS binding instructions, see How to Set Up SSL on IIS 7.

Apache

The following configuration is an example virtual host configured for SSL in Apache:

NGINX

The following configuration is an example NGINX server block with TLS configuration:

Access the server to verify the configuration

1. Add the root certificate to your machine's trusted root store. When you access the website, ensure the entire certificate chain is seen in the browser.

   Note

   It's assumed that DNS has been configured to point the web server name (in this example, www.fabrikam.com) to your web server's IP address. If not, you can edit the hosts file to resolve the name.

2. Browse to your website, and click the lock icon on your browser's address box to verify the site and certificate information.

Verify the configuration with OpenSSL

Or, you can use OpenSSL to verify the certificate.

Upload the root certificate to Application Gateway's HTTP Settings

To upload the certificate in Application Gateway, you must export the .crt certificate into a .cer format Base-64 encoded. Since .crt already contains the public key in the base-64 encoded format, just rename the file extension from .crt to .cer.

Azure portal

To upload the trusted root certificate from the portal, select the HTTP Settings and choose the HTTPS protocol.

Azure PowerShell

Or, you can use Azure CLI or Azure PowerShell to upload the root certificate. The following code is an Azure PowerShell sample.

Note

The following sample adds a trusted root certificate to the application gateway, creates a new HTTP setting and adds a new rule, assuming the backend pool and the listener exist already.

Verify the application gateway backend health

1. Click the Backend Health view of your application gateway to check if the probe is healthy.
2. You should see that the Status is Healthy for the HTTPS probe.

Next steps

To learn more about SSLTLS in Application Gateway, see Overview of TLS termination and end to end TLS with Application Gateway.