cygwin

HOW TO: Password-less SSH login

12 Mar 2008

Steps to create a password-less SSH login

These commands are executed on linux or on a pseudo-linux environment, like cygwin. It will not work under Windows.

  1. Generate the encryption key. Do this on client machine. 

    $ ssh-keygen -t dsa -f ~/.ssh/id_dsa -C "[email protected]"

    A passphrase is recommended, though not required. Enter a passphrase that you can remember. It need not be the same as your password.
     
  2. Skip this step if there are multiple clients connecting to the server.

    $ scp ~/.ssh/id_dsa [email protected]

    Enter the password, when asked.
  3. This step is required if there are multiple clients who need to connect to the server.

    $ cat ~/.ssh/id_dsa | ssh [email protected] 'cat - >> ~/.ssh/authorized_keys'

    Now if you try to connect to the server, it won't ask for your password. If you have setup a passphrase, you are required to enter that.Do the steps below to ensure a password-less login.
  4. Edit your bash_profile to include the following lines. This is adapted to cygwin.

    $ cat >> ~/.bash_profile
    SSH_ENV="$HOME/.ssh/environment"
    function start_agent {
    echo "Initializing new SSH agent..."
    usr/bin/ssh-agent | sed 's/^echo/#echo/' > "${SSH_ENV}"
    echo succeeded
    chmod 600 "${SSH_ENV}"
    . "${SSH_ENV}" > /dev/null
    /usr/bin/ssh-add;
    }
    # Source SSH settings, if applicable
    if [ -f "${SSH_ENV}" ; then
    . "${SSH_ENV}" > /dev/null
    #ps ${SSH_AGENT_PID} doesn't work under cygwin
    ps -ef | grep ${SSH_AGENT_PID} | grep ssh-agent$ >
    /dev/null || {
    start_agent;
    }
    else start_agent;
    fi
  5. For Cygwin, use

    $ cat >> ~/.bash_profile
    if [ -f ${HOME}/.ssh-agent ]; then
    . ${HOME}/.ssh-agent > /dev/null
    fi
    if [ -z "$SSH_AGENT_PID" -o -z "`/usr/bin/ps -a|/usr/bin/egrep \"^[ ]+$SSH_AGENT_PID\"`" ]; then
    /usr/bin/ssh-agent > ${HOME}/.ssh-agent
    . ${HOME}/.ssh-agent > /dev/null
    fi
  6. Now type in the last password of this session.

    $ssh-add ~/.ssh/id_dsa

Ok, so we have a password-less login. This is done through the ssh-agent that hods, manages and responds to requests for private keys.

For more information, read An Illustrated Guide to SSH Agent Forwarding
Adapted from - Using ssh-agent with ssh

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