Enter SSH keys. These cannot be brute-forced – they are simply too complex. If you can, disable password logins in your “sshdconfig” file (on the server) and use keys instead. In case you travel and can’t carry your laptop with you, just keep your private key on a. Manual page for sshd describes format of the file. SSHKNOWNHOSTS FILE FORMAT. The /etc/ssh/sshknownhosts and /.ssh/knownhosts files contain host public keys for all known hosts. The global file should be prepared by the administrator (optional), and the per-user file is maintained automatically: whenever the user connects from an unknown host, its key is added to the per-user file. May 05, 2014  Install putty and generate ssh key to auto log in to Ubuntu server 14 Table of contents: 1. Setting up Ubuntu server 14. Install putty and generate ssh key to auto log in to Ubuntu server.

1. Ubuntu 18.04 Generate Ssh Host Keys
2. Generate Ssh Keys Ubuntu

This section of the Ubuntu Server Guide introduces a powerful collection of tools for the remote control of, and transfer of data between, networked computers called OpenSSH. You will also learn about some of the configuration settings possible with the OpenSSH server application and how to change them on your Ubuntu system.

OpenSSH is a freely available version of the Secure Shell (SSH) protocol family of tools for remotely controlling, or transferring files between, computers. Traditional tools used to accomplish these functions, such as telnet or rcp, are insecure and transmit the user's password in cleartext when used. OpenSSH provides a server daemon and client tools to facilitate secure, encrypted remote control and file transfer operations, effectively replacing the legacy tools.

The OpenSSH server component, sshd, listens continuously for client connections from any of the client tools. When a connection request occurs, sshd sets up the correct connection depending on the type of client tool connecting. For example, if the remote computer is connecting with the ssh client application, the OpenSSH server sets up a remote control session after authentication. If a remote user connects to an OpenSSH server with scp, the OpenSSH server daemon initiates a secure copy of files between the server and client after authentication. OpenSSH can use many authentication methods, including plain password, public key, and Kerberos tickets.

Installation of the OpenSSH client and server applications is simple. To install the OpenSSH client applications on your Ubuntu system, use this command at a terminal prompt:

To install the OpenSSH server application, and related support files, use this command at a terminal prompt:

The openssh-server package can also be selected to install during the Server Edition installation process.

You may configure the default behavior of the OpenSSH server application, sshd, by editing the file /etc/ssh/sshd_config. For information about the configuration directives used in this file, you may view the appropriate manual page with the following command, issued at a terminal prompt:

There are many directives in the sshd configuration file controlling such things as communication settings, and authentication modes. The following are examples of configuration directives that can be changed by editing the /etc/ssh/sshd_config file.

Prior to editing the configuration file, you should make a copy of the original file and protect it from writing so you will have the original settings as a reference and to reuse as necessary.

Copy the /etc/ssh/sshd_config file and protect it from writing with the following commands, issued at a terminal prompt:

The following are examples of configuration directives you may change:

• To set your OpenSSH to listen on TCP port 2222 instead of the default TCP port 22, change the Port directive as such:

  Port 2222

• To have sshd allow public key-based login credentials, simply add or modify the line:

  PubkeyAuthentication yes

  If the line is already present, then ensure it is not commented out.

• To make your OpenSSH server display the contents of the /etc/issue.net file as a pre-login banner, simply add or modify the line:

  Banner /etc/issue.net

  In the /etc/ssh/sshd_config file.

Ubuntu 18.04 Generate Ssh Host Keys

After making changes to the /etc/ssh/sshd_config file, save the file, and restart the sshd server application to effect the changes using the following command at a terminal prompt:

Generate Ssh Keys Ubuntu

Many other configuration directives for sshd are available to change the server application's behavior to fit your needs. Be advised, however, if your only method of access to a server is ssh, and you make a mistake in configuring sshd via the /etc/ssh/sshd_config file, you may find you are locked out of the server upon restarting it. Additionally, if an incorrect configuration directive is supplied, the sshd server may refuse to start, so be extra careful when editing this file on a remote server.

SSH keys allow authentication between two hosts without the need of a password. SSH key authentication uses two keys, a private key and a public key. Generate key from user pass.

To generate the keys, from a terminal prompt enter:

This will generate the keys using the RSA Algorithm. During the process you will be prompted for a password. Simply hit Enter when prompted to create the key.

By default the public key is saved in the file ~/.ssh/id_rsa.pub, while ~/.ssh/id_rsa is the private key. Now copy the id_rsa.pub file to the remote host and append it to ~/.ssh/authorized_keys by entering:

Finally, double check the permissions on the authorized_keys file, only the authenticated user should have read and write permissions. If the permissions are not correct change them by:

You should now be able to SSH to the host without being prompted for a password.

• Ubuntu Wiki SSH page.