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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-FBB9ED48-3C0F-4B2D-90FC-52127698F253" xml:lang="en"><title>IPv4/IPv6

    13 dual-stack</title><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <p>The IP protocol is responsible for routing the data between networks

    15 and it employs an addressing system to achieve this. The Internet protocol

    16 version 4 (IPv4) has a number of security problems and lacks privacy and authentication

    17 mechanisms below the application layer. IPv6 provided numerous security enhancements,

    18 such as mandatory implementation of Authentication Header and Encapsulated

    19 Security Payload.</p>

    20 <p><i>IPv4/IPv6 dual-stack</i> enables applications to choose the protocol

    21 to use or automatically select it according to address type. This feature

    22 is supported from Symbian OS v7.0s onwards.</p>

    23 <fig id="GUID-E46DA5BE-AB7E-40C6-9A75-1BB7E9D21034"><title>IPv4/IPv6 dual-protocol stack</title><image href="GUID-D81EAF75-EF8C-4B62-8866-439E29325E8A_d0e11345_href.png"/></fig>

    24 <p>It is possible to establish a secure connection from application to

    25 application and also from router to router. Security features implemented

    26 in low-level protocols (like IPv6) are automatically available to higher-level

    27 protocols and applications.</p>

    28 <p>For more information, see <xref href="GUID-B144EAB9-53AB-579B-9E12-B16518E4FC01.dita">Networking

    29 Services Guide</xref>.</p>

    30 </conbody></concept>