The old-boy's network is powerful indeed, an unfair impediment to those that would seek to make a contribution, but it can be defeated with a combination of:
Skill (the result of practice and effort)
Technique (developing a point of view)
Charisma (the confidence to care about connecting with others)
Risk-taking (and not being confused by false fear appearing real)
Consistency and keeping promises
It would be fair, efficient and honest if everyone had an easy introduction and got the benefit of the doubt. Until that happens, though, outsiders of all kinds will have to rely on all of these skills instead.