6 This code is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License version 2 only, as 8 published by the Free Software Foundation. Oracle designates this 9 particular file as subject to the "Classpath" exception as provided 10 by Oracle in the LICENSE file that accompanied this code. 11 12 This code is distributed in the hope that it will be useful, but WITHOUT 13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 version 2 for more details (a copy is included in the LICENSE file that 16 accompanied this code). 17 18 You should have received a copy of the GNU General Public License version 19 2 along with this work; if not, write to the Free Software Foundation, 20 Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 22 Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 23 or visit www.oracle.com if you need additional information or have any 24 questions. 25 --> 26 <HTML> 27 <HEAD> 28 <META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=iso-8859-1"> 29 <TITLE>Networking Properties</TITLE> 30 </HEAD> 31 <BODY LANG="en-US" DIR="LTR"> 32 <H1 style="text-align:center">Networking Properties</H1> 33 <P>There are a few standard system properties used to 34 alter the mechanisms and behavior of the various classes of the 35 java.net package. Some are checked only once at startup of the VM, 36 and therefore are best set using the -D option of the java command, 37 while others have a more dynamic nature and can also be changed using 38 the <a href="../../lang/System.html#setProperty(java.lang.String,%20java.lang.String)">System.setProperty()</a> API. 39 The purpose of this document is to list 40 and detail all of these properties.</P> 41 <P>If there is no special note, a property value is checked every time it is used.</P> 42 <a id="Ipv4IPv6"></a> 43 <H2>IPv4 / IPv6</H2> 44 <UL> 45 <LI><P><B>java.net.preferIPv4Stack</B> (default: false)<BR> 46 If IPv6 is available on the operating system the 47 underlying native socket will be, by default, an IPv6 socket which 48 lets applications connect to, and accept connections from, both 49 IPv4 and IPv6 hosts. However, in the case an application would 50 rather use IPv4 only sockets, then this property can be set to <B>true</B>. 51 The implication is that it will not be possible for the application 52 to communicate with IPv6 only hosts.</P> 53 <LI><P><B>java.net.preferIPv6Addresses</B> (default: false)<BR> 54 When dealing with a host which has both IPv4 55 and IPv6 addresses, and if IPv6 is available on the operating 56 system, the default behavior is to prefer using IPv4 addresses over 57 IPv6 ones. This is to ensure backward compatibility, for example 58 applications that depend on the representation of an IPv4 address | 6 This code is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License version 2 only, as 8 published by the Free Software Foundation. Oracle designates this 9 particular file as subject to the "Classpath" exception as provided 10 by Oracle in the LICENSE file that accompanied this code. 11 12 This code is distributed in the hope that it will be useful, but WITHOUT 13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 version 2 for more details (a copy is included in the LICENSE file that 16 accompanied this code). 17 18 You should have received a copy of the GNU General Public License version 19 2 along with this work; if not, write to the Free Software Foundation, 20 Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 22 Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 23 or visit www.oracle.com if you need additional information or have any 24 questions. 25 --> 26 <HTML lang="EN"> 27 <HEAD> 28 <META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=iso-8859-1"> 29 <TITLE>Networking Properties</TITLE> 30 </HEAD> 31 <BODY LANG="en-US" DIR="LTR"> 32 <H1 style="text-align:center">Networking Properties</H1> 33 <P>There are a few standard system properties used to 34 alter the mechanisms and behavior of the various classes of the 35 java.net package. Some are checked only once at startup of the VM, 36 and therefore are best set using the -D option of the java command, 37 while others have a more dynamic nature and can also be changed using 38 the <a href="../../lang/System.html#setProperty-java.lang.String-java.lang.String-">System.setProperty()</a> API. 39 The purpose of this document is to list 40 and detail all of these properties.</P> 41 <P>If there is no special note, a property value is checked every time it is used.</P> 42 <a id="Ipv4IPv6"></a> 43 <H2>IPv4 / IPv6</H2> 44 <UL> 45 <LI><P><B>java.net.preferIPv4Stack</B> (default: false)<BR> 46 If IPv6 is available on the operating system the 47 underlying native socket will be, by default, an IPv6 socket which 48 lets applications connect to, and accept connections from, both 49 IPv4 and IPv6 hosts. However, in the case an application would 50 rather use IPv4 only sockets, then this property can be set to <B>true</B>. 51 The implication is that it will not be possible for the application 52 to communicate with IPv6 only hosts.</P> 53 <LI><P><B>java.net.preferIPv6Addresses</B> (default: false)<BR> 54 When dealing with a host which has both IPv4 55 and IPv6 addresses, and if IPv6 is available on the operating 56 system, the default behavior is to prefer using IPv4 addresses over 57 IPv6 ones. This is to ensure backward compatibility, for example 58 applications that depend on the representation of an IPv4 address |