@venus-> cat /usr/src/tools/tools/nanobsd/defaults.sh | grep NANO_KERNEL=
NANO_KERNEL=GENERIC

# i am going to simulate i386
vi /usr/src/sys/i386/conf/GENERIC

--
other way is modify defaults.sh NANO_KERNEL=NEW-Kernel
vi /usr/src/sys/i386/conf/NEW-Kernel

em0 -> keep this ethernet, comment out all others is fine
device          em                      # Intel PRO/1000 Gigabit Ethernet Family