IPv6
Symbian OS supports the IPv4/IPv6 dual-protocol stack beginning with Symbian OS v7.0s. The dual-stack enables applications to choose the protocol to use or automatically select it according to address type.
The Internet protocol v4 (IPv4) has a number of security problems and lacks feasible privacy and authentication mechanisms below the application layer. IPv6 provides numerous enhancements to the previous version of Internet protocol, including security enhancements. The main difference is built-in support for the IPv6 Authentication Header and Encapsulating Security Header, which allows implementation of security protocols directly inside IPv6, instead of using different protocols and layers built over it. It is possible to establish a secure connection from application to application and also from router to router. Security features implemented in low-level protocols (like IPv6) are automatically available for higher-level protocols and applications.
For more information and a definition of IPv6-compatible functions, refer to general Symbian OS networking documentation.