The Free On-line Dictionary of Computing (19 January 2023):

firewall machine
flytrap
Venus flytrap

    A network firewall implemented as a
   separate piece of hardware or a virtual machine.

   (2020-06-25)


The Jargon File (version 4.4.7, 29 Dec 2003):

Venus flytrap
 n.

    [after the insect-eating plant] See firewall machine.