This is a rather large question mark in this area. Based on linguistic evidence (mostly place-names), they don't seem to have been a Semitic people, certainly not a Canaanite group. Because artifacts recovered from digs resemble those of Greek groups (but not Canaanites), they seem to have been at least from the Aegean, if not Greek themselves. See here.

The main issue with identifying them is that they integrated into Canaanite society over time, adopting the Canaanite pantheon and eventually a Canaanite language. The lack of much documentation of their language beyond a relatively small number of names is particularly troublesome--a solid relationship with other languages would aid in the determination of where they came from.