What is the minimum number of network connections in a multi homed firewall?

A multi-homed firewall is defined by having multiple network interfaces connecting distinct security zones. The minimum viable configuration requires three interfaces: one facing the untrusted external network such as the internet, one facing the trusted internal LAN, and one facing a DMZ for hosting publicly accessible services. This three-interface design is the foundational baseline for multi-homed firewall architectures and enables proper traffic segmentation between all three zones.

Five connections is more than the minimum required - a multi-homed firewall can function with as few as three network interfaces.

Four connections exceeds the minimum - the minimum viable multi-homed configuration requires only three interfaces, not four.

Two connections describes a simple dual-homed device that connects only two segments, which does not meet the multi-homed definition requiring three or more separate network segments.