Kung Fu Vs. Kickboxing?

Ive wondered how a kung fu fighter defends and attacks a boxer and kung fu fighters dont have their guards like a boxer's so how do they defend? Also, how would a kung fu fight attack a boxer? what would happen if someone like jackie chan went against chuck liddel? plz not UFC fans that will say boxing and MMA will beat kung fu anytime because im looking for a true non biased answer