Followup: I found ifup and ifdown. ifup eth0 does nothing.

ifdown eth0 (as root) gives me:

cat: /var/run/udhcpc.eth0.pid: No such file or directory
cat: /var/run/udhcpc.eth0.pid: No such file or directory
SIOCGIFFLAGS: No such device

Also found if I do ifconfig eth0, I get:

ifconfig: eth0: error fetching device information: Device not found

Don't know if this is helpful.