The WiFi Pineapple TETRA provides two Ethernet ports. A WAN port via a traditional RJ45 port, as well as a LAN port accessible by its USB ETH port. The USB ETH port connects the host device to the LAN via an onboard Realtek USB Ethernet controller.
The WAN port is connected to eth0 on the WiFi Pineapple TETRA and by default will attempt to obtain an IP address from DHCP.
The LAN port is connected to eth1 on the WiFi Pineapple TETRA and hosts the internal DHCP server which will offer an IP address in the 172.16.42.x range by default.