A middlebox is a computer networking device that transforms, inspects, filters, and manipulates traffic for purposes other than packet forwarding.[1] Examples of middleboxes include firewalls, network address translators (NATs), load balancers, and deep packet inspection (DPI) devices.[2]
The term middlebox was coined in 1999 by UCLA computer science professor Lixia Zhang.[1][3]
mboxtaxonomy
was invoked but never defined (see the help page).