The Ethernet network configuration is in the file "network.txt".
Example:
#network.txt
use_dhcp=0
#dhcp_retry_time=0
ip_address=192.168.2.251
net_mask=255.255.255.0
#hostname=allwinner_34020E
#ntp_server=0.0.0.0
#ntp_utc_offset=0.0