The Jargon File (version 4.4.7, 29 Dec 2003):
iron box
n.
[Unix/Internet] A special environment set up to trap a cracker logging in
over remote connections long enough to be traced. May include a modified
shell restricting the cracker's movements in unobvious ways, and ?bait?
files designed to keep him interested and logged on. See also back door,
firewall machine, Venus flytrap, and Clifford Stoll's account in The
Cuckoo's Egg of how he made and used one (see the Bibliography in Appendix
C). Compare padded cell, honey pot.
The Free On-line Dictionary of Computing (30 December 2018):
iron box
[Unix/Internet] A special environment set up to trap a
cracker logging in over remote connections long enough to be
traced. May include a modified shell restricting the
cracker's movements in unobvious ways, and "bait" files
designed to keep him interested and logged on. See also back
door, firewall machine, Venus flytrap, and Clifford
Stoll's account in "The Cuckoo's Egg" of how he made and
used one. Compare padded cell.
[Jargon File]