Excuse my ignorance as I am not form a networking background. But our employees (from PC's joined to our network) access a 3rd party application hosted in another organisations network. This isn’t public facing app and there must be some form of link between our network and theirs (and their application server). What role does our firewall play in establishing the link to their network / the app server? What would you look for from a security angle to ensure the link is secure, i.e. data sent to/from our clients to the app server cannot be easily intercepted? Please keep answers simple / management friendly?