1. Ssh Dsa

The following example uses DSA key pair, this will allow you to run scripts and login from a remote machine against RouterOS using Public/Private key authentication. Host to RouterOS. Note: commands are run using FreeBSD - should be similar on other platforms. 1) Create a key using ssh-keygen%ssh-keygen -t dsa. This creates a DSA key pair that. If both your client and server have OpenSSH 6.8 or newer, you can use the UpdateHostKeys yes option in your sshconfig or /.ssh/config.For example: Host. UpdateHostKeys yes This makes SSH store all host keys that the server has to knownhosts, and when a server changes or removes one host key, the key is also changed or removed in your knownhosts.

Introduction

SSH (Secure Shell) allows secure remote connections between two systems. With this cryptographic protocol, you can manage machines, copy, or move files on a remote server via encrypted channels.

There are two ways to login onto a remote system over SSH – using password authentication or public key authentication (passwordless SSH login).

In this tutorial, you will find out how to set up and enable passwordless SSH login.

• Access to command line/terminal window
• User with sudo or root privileges
• A local server and a remote server
• SSH access to a remote server via command line/terminal window

You may already have an SSH key pair generated on your machine. To see whether you have SSH keys on the system, run the command:

If the output tells you there are no such files, move on to the next step, which shows you how to generate SSH keys.

In case you do have them, you can use the existing keys, back them up and create a new pair or overwrite it.

1. The first thing you need to do is generate an SSH key pair on the machine you are currently working on.

In this example, we generate a 4096-bit key pair. We also add an email address, however this is optional. The command is:

2. Next, type in the location where you want to store the keys or hit Enter to accept the default path.

3. It also asks you to set a passphrase. Although this makes the connection even more secure, it may interrupt when setting up automated processes. Therefore, you can type in a passphrase or just press Enter to skip this step.

4. The output then tells you where it stored the identification and public key and gives you the key fingerprint.

5. Verify you have successfully created the SSH key pair by running the command:

You should see the path of the identification key and the public key, as in the image below:

You can upload the public SSH key to a remote server with the ssh-copy-id command or the cat command. Below you can find both options.

To enable passwordless access, you need to upload a copy of the public key to the remote server.

1. Connect to the remote server and use the ssh-copy-id command:

2. The public key is then automatically copied into the .ssh/authorized_keys file.

Another way to copy the public key to the server is by using the cat command.

1. Start by connecting to the server and creating a .ssh directory on it.

2. Then, type in the password for the remote user.

3. Now you can upload the public key from the local machine to the remote server. The command also specifies that the key will be stored under the name authorized_keys in the newly created .ssh directory:

With the SSH key pair generated and the public key uploaded to the remote server, you should now be able to connect to your dedicated server without providing a password.

Check whether the setup works by running the command:

The system should directly log you in to the remote server, no password required.

Note: Once you verify that you can SHH into the remote serve without a password, consider disabling SSH password authentication altogether. It will add another layer of security and secure your server from brute-force attacks.

Optional: Troubleshooting Remote Server File Permissions

File permissions on the remote server may cause issues with passwordless SSH login. This is a common issue with older versions of SSH.

If you are still prompted for a password after going through all the steps, start by editing file permissions on the remote server.

• Set permissions 700 for the .ssh directory.
• Set permissions 640 for the .ssh/authorized_keys directory.

Edit file permissions with the following command:

Enter your password when prompted. There will be no output if the action was successful. The issue should be resolved now.

If you want to automate updates and other tasks, or seamlessly SSH into a remote server, you should enable passwordless SSH login.

The instructions outlined in this article should have helped you to do so.

For more SSH commands, check out these 19 common SSH commands in Linux with examples.

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How do I create a host key file to use with my applications as I can not use system defined /etc/ssh/ssh_host_rsa_key for non-root account under Linux / Unix / Apple OS X / *BSD operating systems?
You need to use a command called ssh-keygen. This command generates, manages and converts authentication keys for ssh. It can create RSA keys for use by SSH protocol version 1 and RSA or DSA keys for use by SSH protocol version 2. he type of key to be generated is specified with the -t option. If invoked without any arguments, ssh-keygen will generate an RSA key for use in SSH protocol 2 connections. The -f option specifies the filename of the key file.

Why create a new host key files?

You may need a new key file:

1. Your system is compromised.
2. Your keys are stolen.
3. You forgotten the passphrase.
4. Your application need a new host key.
5. You can not read the default system key files stored in /etc/ssh/ directory but your non-root application needs key.
6. You got an error message which read as “Could not load host key: /etc/ssh/ssh_host_key*”.

ssh-keygen Syntax

The syntax is:

Example

Create a host key file in your $HOME/.ssh/myapp as follows. First, create a directory to store your host key file, enter:
$ mkdir -p $HOME/.ssh/myapp
To create a host RSAv2 key file, run:
$ ssh-keygen -t rsa -f $HOME/.ssh/myapp/rsa_key_file
Sample outputs:

Type the following commands to verify the keys:
$ ls -l $HOME/.ssh/myapp/
Sample outputs:

You can now use keys with your app:
$ mycool-app -key $HOME/.ssh/myapp/rsa_key_file -d

Ssh Dsa

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