Ephemeral Ports

Ephemeral ports are temporary ports that are assigned by a machine's IP stack from a designated range of ports that are specifically for temporary use. When you terminate a connection to an ephemeral port, that port is available for reuse. However, most IP stacks do not reuse that port number until the entire pool of ephemeral ports have been used. So, if the client program reconnects, it is assigned a different ephemeral port number for its side of the new connection.

The following sections provide system-specific information about ephemeral ports.

IBM AIX Operating Environment

AIX uses the no command to set network options. AIX uses two separate ephemeral port ranges, one for transmission control protocol (TCP) and one for user datagram protocol (UDP). Both of these ports default to values that range from 32768 through 65535.

Under AIX, you query the ephemeral port range as follows:

To change these range values, use the -o option, as follows:

If you want to make this change permanent, insert your no commands in /etc/rc.tcpip. Add the commands at a location before the script starts the server daemons.

Linux Operating Environment

The Linux port range is in the ip_local_port_range file that is found in /proc/sys/net/ipv4/. To change the range, simply edit the file. Be aware that a range change that is made in this file is not permanent; the change reverts back the next time you start the system. To make the change permanent, add the following line to /etc/rc.local:

Sun Solaris Operating Environment

Solaris uses the ndd utility program to configure the IP stack. Solaris uses two separate ephemeral port ranges, one for TCP and UDP. Both ports default to values from 32768 through 65535.

The following examples illustrate how you can query and change the settings:

Example 1: Query the Current Settings

Example 2: Change the Settings

These changes last until the next time you start your system.

Hewlett-Packard HP-UX Operating Environment

HP-UX also uses ndd to configure the IP stack, but it is found in the /usr/bin directory (/usr/bin/ndd). HP-UX uses two separate ephemeral port ranges, one for TCP and UDP. Both of these ports default to values from 49152 through 65535. You query and change the setting under HP-UX the same as is shown for Solaris in the previous section.

As is the case with Solaris, any changes under HP-UX last only until the next time you start your system.

Microsoft Windows Operating Environment

Windows Server 2008 and later use a default range of values from 49152 through 65535. For details about how to change a range under Windows, see the Microsoft knowledge-base article 929851, "The default dynamic port range for TCP/IP has changed in Windows Vista and Windows Server 2008."

Earlier releases of Windows use a default range of values from 1024 through 4999. For details about these earlier releases, see the Microsoft knowledge-base article 196271, "When you try to connect from TCP ports greater than 5000, you receive the error 'WSAENOBUFS (10055).'

Operating System and Release Information

Product Family	Product	System	SAS Release
			Reported	Fixed*
SAS System	N/A	Microsoft Windows 2000 Professional
		Microsoft® Windows® for 64-Bit Itanium-based Systems
		Microsoft Windows Server 2003 Datacenter 64-bit Edition
		Microsoft Windows Server 2003 Enterprise 64-bit Edition
		Microsoft Windows XP 64-bit Edition
		Microsoft® Windows® for x64
		Microsoft Windows 2000 Advanced Server
		Microsoft Windows 2000 Datacenter Server
		Microsoft Windows 2000 Server
		Microsoft Windows Server 2003 Datacenter Edition
		Microsoft Windows Server 2003 Enterprise Edition
		Microsoft Windows Server 2003 Standard Edition
		Microsoft Windows Server 2003 for x64
		Microsoft Windows Server 2008
		Microsoft Windows Server 2008 for x64
		Microsoft Windows XP Professional
		Windows 7 Enterprise 32 bit
		Windows 7 Enterprise x64
		Windows 7 Home Premium 32 bit
		Windows 7 Home Premium x64
		Windows 7 Professional 32 bit
		Windows 7 Professional x64
		Windows 7 Ultimate 32 bit
		Windows 7 Ultimate x64
		64-bit Enabled AIX
		64-bit Enabled HP-UX
		64-bit Enabled Solaris
		ABI+ for Intel Architecture
		AIX
		HP-UX
		HP-UX IPF
		IRIX
		Linux
		Linux for x64
		Linux on Itanium
		OpenVMS Alpha
		OpenVMS on HP Integrity
		Solaris
		Solaris for x64
		Tru64 UNIX

* For software releases that are not yet generally available, the Fixed Release is the software release in which the problem is planned to be fixed.

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Type:	Usage Note
Priority:

Date Modified:	2011-08-15 11:11:25
Date Created:	2011-08-09 10:21:38