crunchy outside, chewy center
expressionsecurity
The classic critique of perimeter-only security: a hard shell around a soft, defenseless inside.
Bill Cheswick's 1990 description of firewalled networks - a sort of crunchy shell around a soft, chewy center - is still the sharpest one-liner about why one perimeter is not a strategy. Everything from segmentation to zero trust is an answer to it.
Also known as: hard shell, soft center, M&M security