For backwards compatibility, the engine was sometimes called using
an int for the server port directly. This would cause an error, so
casting to str() solves that without needing to change anything.
Updated the Geneva engine to allow for port ranges and lists
specifying which ports to monitor to modify packets. This works
using either a range like port 5000 to port 6000 =>
--server-port 5000:6000 or a list like port 5000, 5500, and 6000
=> --server-port 5000,5500,6000.
Any error checking on the port variable will be handled by the
iptables command.