ruby on rails ssh connection check validity

Question

I'm making an ssh connection in my controller and displaying a view if the connection is established sucessfully. I need my action to redirect to 'denied_access' view if the connection is not established Here is my view where use enters his details:

<%= form_for :check_validity, :method => "get", :url => {:action => "check_validity"} do |f| %>
//enters user name and password here and submits
<% end%>

the check validity action in controller:

 def check_validity
     @USER = params[:check_validity][:username]
     @PASS = params[:check_validity][:password]
     @DOMAIN = params[:check_validity][:domain]
     @HOST = 'hostname'

     Net::SSH.start( @HOST, @USER, :password => @PASS ) do|ssh|

     @result = ssh.exec!("/lclapps/oppen/http/ldap-group-list-2.4.3.py #{@DOMAIN} #{@USER} #{@PASS}")
     end
        respond_to do |format|
         if(@result =~ /Informatica Developer/)
          format.html{redirect_to display_command_list_path({:username => @USER})}
         else
          format.html{redirect_to denied_access_path}
         end
         end
  end

Here the connection is established and is checking for Informatica Developer string in the resutl and redirecting to display_command_list_path. But i want to check whether the connection is established or not even before checking this string and redirect to denied_access_path if the connection is not established. How can i do that?

Answer 1

When attempting to connect with Net::SSH.start you will get a Net::SSH::AuthenticationFailed exception if the credentials are invalid.

begin
  Net::SSH.start( @HOST, @USER, :password => @PASS ) do |ssh|
    # ...
  end
rescue Net::SSH::AuthenticationFailed => e
  # redirect to denied_access_path
end

# your respond_to block ...

I should also mention, if the @HOST is bad, it will raise a SocketError. You could add a second rescue to the above code for that.