qemu problem

Hi, i'm trying to run kernel with qemu but i get some errors while running this command " qemu-system-x86_64 --nographic -M pc -no-reboot -net nic,model=e1000 -net nic,vlan=0 -net user,hostfwd=tcp:17777:10.0.2.15:22 -hda hd.img -append "root=/dev/hda1 debug rw console=ttyS0,115200" -s -kernel " error says that qemu-system-x86_64: -net user,hostfwd=tcp:17777:10.0.2.15:22: invalid host forwarding rule 'tcp:17777:10.0.2.15:22' qemu-system-x86_64: -net user,hostfwd=tcp:17777:10.0.2.15:22: Device 'user' could not be initialized any help ?