Ephemeral port
<networking> A
TCP or
UDP port number that is automatically allocated from a predefined range by the TCP/IP stack software, typically to provide the port for the client end of a
client-server communication.
BSD used ports 1024 through 4999 as ephemeral ports, though it is often desirable to increase this allocation.
(http://www.ncftpd.com/ncftpd/doc/misc/ephemeral_ports.html).
