The correct arguments to qemu are
-netdev user,id=ethernet.0,hostfwd=tcp::5555-:1522,hostfwd=tcp::9999-:9,hostfwd=tcp::17010-:17010,hostfwd=tcp::17013-:17013
to forward several host ports to the guests ports on ethernet.0
-device rtl8139,netdev=ethernet.0
to define the emulated hardware of ethernet.0
They are both required and the netdev's value of the -device option
must match the id's value of the -netdev option.
