Using Cygwin SSH with Putty Pageant

On windows I mostly use Putty as my SSH client. But in some cases for example when I use unison or rsync I use the ssh client from cygwin.

Following good practice I use public key authentication and Putty's Pageant to manage my password protected keys. This works great with Putty and Plink. I thought this would be great if I could use the same agent for cygwin too. As often the solution already existed in the form of ssh-pageant.

Here is a small tutorial how to set it up:

1. Download the prebuilt version of ssh-pageant from github (direct link).
2. Upack it and copy the ssh-pageant.exe to your cygwin's /usr/local/bin directory
3. You need to edit your .bash_profile file in order to start the ssh-pageant on opening a shell
   The method I use is different form the one described in ssh-pageant's readme as it only starts one instance of ssh-pageant and reuses this in subsequent sessions. It is based on the Github Help about ssh keys.

Add this at the end of your .bash_profile

# Setup SSH Agent
 
SSH_ENV="$HOME/.ssh/environment"
 
function start_agent {
  echo "Initializing new SSH agent..."
  /usr/local/bin/ssh-pageant | sed 's/^echo/#echo/' > "${SSH_ENV}"
  echo "succeded"
  chmod 600 "${SSH_ENV}"
  . "${SSH_ENV}" > /dev/null
  #/usr/bin/ssh-add;
}
 
if [ -f "${SSH_ENV}" ]; then
  . "${SSH_ENV}" > /dev/null
  ps -ef | grep $SSH_PAGEANT_PID | grep ssh-pageant$ > /dev/null || {
    start_agent;
  }
else
  start_agent;
fi

Now you should be able to login using cygwin's ssh.exe with the same comfort of putty.