Symfony routing to external site including session value
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I'm porting a legacy system that uses Symfony framework. I have almost no experience on Symfony at all.

I need to overwrite a route to an action to an external site and including a session value as a parameter. 

This is the current `routing.yml` code

    mysystemtool:
      url:   /:module/mysystemtool/tool/*
      param: { action: mysystemtool }

And I need to redirect to a url like `http://thirdpartyurl.com/?session_param=session_value`

Any idea how to do this?