For commonly used services the string argument service can be used instead of a port number. If several Ethernet links exists, the one that the simulated machine is connected to must be specified using ethernet-link.
The service-node that will perform the port forwarding is selected automatically based on the Ethernet link unless one is specified using the service-node argument.
The flags -tcp and -udp can be used to specify the protocol to forward. The default is to forward only the usual protocol for named services and both tcp and udp for numerically specified ports.
The host-port given is only a hint, and the actual port used may be a different one. The command output shows the actual port used, and it can also be determined by inspecting the connections attribute in the appropriate port forwarding object.
The flag -f can be used to cause the command to fail if the suggested host port could not be allocated, without the flag the command will assign the first available port starting from the specified host port and upwards.