An ephemeral (short-lived) port is a transport protocol port for Internet Protocol (IP) communications allocated automatically from a predefined range by the TCP/IP stack software. It is typically used by the Transmission Control Protocol (TCP), User Datagram Protocol (UDP), or the Stream Control Transmission Protocol (SCTP) as port for the client end of a client-server communication when the application doesn't bind the socket to a specific port number, or by a server application to free up a service's well-known listening port and establish a service connection to the client host. The allocations are temporary and only valid for the duration of the connection. After completion of the communication session the ports become available for reuse, although most implementations simply increment the last used port number until the ephemeral port range is exhausted.
The IANA suggests 49152 to 65535 as "dynamic and/or private ports." [1]
The Berkeley Software Distribution (BSD) uses ports 1024 through 4999 as ephemeral ports, though it is often desirable to increase this allocation.
Many Linux kernels use 32768 to 61000. The file system path /proc/sys/net/ipv4/ip_local_port_range contains the range in use.
Microsoft Windows operating systems through Server 2003 use the range 1025 to 5000 as ephemeral ports.[2] Windows Vista and Server 2008 use the IANA range. [3]
FreeBSD uses the IANA port range since release 4.6.
See also
References
External links
- The Ephemeral Port Range at NcFTP.com
This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
