Most security experts trace the firewall’s roots to work done at Digital Equipment Corp. in the late 1980s. Jeff Mogul, Paul Vixie, Brian Reid, Fred Avolio, and Brent Chapman were associated in some way with the roots of firewall technology. Marcus Ranum says his reputation as inventor of the firewall is “marketing BS” David Pensak claims to have built the first commercially successful firewall. Nir Zuk says he developed the technology used in all firewalls today.”]
Source: https://www.darkreading.com/analytics/who-invented-the-firewall-