who is a cracker....?

Cracker

One who breaks security on a system. Coined ca. 1985 by hackers
in defense against journalistic misuse of hacker (q.v., sense 8). An
earlier attempt to establish ‘worm’ in this sense around 1981–82
on Usenet was largely a failure.

Use of both these neologisms reflects a strong revulsion against
the theft and vandalism perpetrated by cracking rings. While it is
expected that any real hacker will have done some playful cracking
and knows many of the basic techniques, anyone past larval stage
is expected to have outgrown the desire to do so except for immediate,
benign, practical reasons (for example, if it’s necessary to get
around some security in order to get some work done).
Thus, there is far less overlap between hackerdom and crackerdom
than the mundane reader misled by sensationalistic journalism
might expect. Crackers tend to gather in small, tight-knit,
very secretive groups that have little overlap with the huge, open
poly-culture this lexicon describes; though crackers often like to
describe themselves as hackers, most true hackers consider them a
separate and lower form of life.

It’s clear that the term cracker is absolutely meant to be derogatory. One
shouldn’t take the tone too seriously though, as The Jargon File is done with a
sense of humor, and the above is said with a smile. As we can see from the
above, illegal or perhaps immoral activity is viewed with disdain by the “true
hackers,” whomever they may be. It also makes reference to cracker being a
possible intermediate step to hacker, perhaps something to be overcome.