SSH Without a Password

The following steps can be used to ssh from one system to another without specifying a password.
Notes:

  • The system from which the ssh session is started via the ssh command is the client.
  • The system that the ssh session connects to is the server.
  • These steps seem to work on systems running OpenSSH.
  • The steps assume that a DSA key is being used. To use a RSA key substitute ‘rsa’ for ‘dsa’.
  • The steps assume that you are using a Bourne-like shell (sh, ksh or bash)
  • You should consider the security risks before implementing this feature

Steps:

  1. On the client run the following commands:

  2. $ mkdir -p $HOME/.ssh
      • $ chmod 0700 $HOME/.ssh
      • $ ssh-keygen -t rsa -f $HOME/.ssh/id_rsa -P ''

        This should result in two files, $HOME/.ssh/id_rsa (private key) and $HOME/.ssh/id_rsa.pub (public key).

        • Copy $HOME/.ssh/id_rsa.pub to the server.

        • On the server run the following commands:

        • $ cat id_rsa.pub >> $HOME/.ssh/authorized_keys2
        • $ chmod 0600 $HOME/.ssh/authorized_keys2

        Depending on the version of OpenSSH the following commands may also be required:

        $ cat id_rsa.pub >> $HOME/.ssh/authorized_keys

$ chmod 0600 $HOME/.ssh/authorized_keys

        An alternative is to create a link from authorized\_keys2 to authorized\_keys:
        
        <pre>$ cd $HOME/.ssh && ln -s authorized_keys2 authorized_keys</pre>
        
          * On the client test the results by ssh&#8217;ing to the server:
          * <pre>$ ssh -i $HOME/.ssh/id_rsa server</pre>
        
          * (Optional) Add the following $HOME/.ssh/config on the client: 
            <pre>Host server

IdentityFile ~/.ssh/id_rsa

        This allows ssh access to the server without having to specify the path to the id_rsa file as an argument to ssh each time.